Table of Contents Shibaura Machine Engineering Review vol.28

Introductory Note2

New "Shibaura Machine"

Special Article

4
7

Slip Ahead

11

Research of Optimized Grease Film on Sliding Surfaces

Technical Paper

16
20
24
Technical Report

DX by the New "Shibaura Machine"

Development of PVD + CVD Vacuum Integrated System ; Application to MoistureResistant Multilayer Reflective Film for Heads-up Display Mirror
Numerical Analysis on an Extrusion Process in a Twin-Screw Extruder
Investigation of Pressure Propagation Characteristics in Die Casting Method28

Development of Plasticization Device for Polyolefin-Based Resin Molding with High
Color Dispersion and High Plasticization Capacity

32

Optimization of Extrusion Process Engineering for the Invention of High-Performance
Materials

37

Development of High-Precision Machining Technology Using the BTA Deep Hole
Drilling Machine DBH

42

Ultra-Precision Machining Technology for Contributing to Higher Power Density ofFuel Cell（FC）Stacks

47

Extended Battery Life of the Resolver Multi-Turn ABS and its Contribution to the
Circular Economy

51

Training Junior Employees using Digital Technology : Standardized Documents inVideo Format

55

Development of an AI-based Function to Monitor the State of Machining during
Cutting in the Double Column Type Machining Center

New Product Introduction

59
62
64
66
68
70
Series1

Introduction of Large-Size Electric Injection Molding Machine EC1800SXⅢIntroduction of the Newest Die Casting Machine DC1300R-E
Introduction of the High-Shear Processing Machine HSE-48
Introduction of Real-time Collision Check Function to Prevent Machine Collisions
and Interference
Introduction of the USM-20B（H）High-Precision Grooving and Cutting Machine
Introduction of the TCmini TC12 Series

73

History of Ultra-Precision Machine Tools and Contributions of Shibaura Machine to
the Development of Ultra-Precision Machining Technology

Patent News

93

Introduction to Patents

Prepared Critique96

My Expectations for Shibaura Machine

Shibaura Machine Engineering Review

Introductory Note

Introductory Note

New "Shibaura Machine"

Special Article

President,
Chief Executive Officer andChief Operating Officer

Shigetomo SAKAMOTO

introduce machinery and equipment.
The factory was later designated a munitions plant. Although the

our name from Toshiba Machine to Shibaura Machine on April 1,

company experienced hardship over its long history, we managed

2020 to mark a fresh start. As Shibaura Machine, we have establishedto find a way to survive with a wide range of machinery anda medium-term “Management Reform Plan” and a more forward-

equipment through all-out efforts to provide technical education

looking “Long-term Vision 2030”, aiming at further growth, as weand training for employees, laying the foundation for us to rebuild

also address structural reforms on a larger scale.

after the war.
Thereafter, our company has continued to develop machinery

technological innovation is advancing at a breathtaking pace. Now

and equipment to meet the demands of the times and has provided

more than ever, we need to be committed to the ongoing creation ofa wide range of high-performance manufacturing equipment which

technologies to accommodate megatrends, such as climate change

supported rapid economic growth in post-war Japan, such as

and resource scarcity, changes in population structures, andprinting machines, roll grinders, master gear hobbing machines

technological advancements, which global manufacturers like(designated as a Mechanical Engineering Heritage), and our core

Shibaura Machine are now facing. To achieve this, we endeavor to

products today which include injection molding machines, diefurther develop the technologies which have been in our hands since

casting machines, and extrusion machines.
However, the world’s goals have dramatically changed, shifting

supplement them. We have a history of changing with the demands

from an economy-oriented era of mass production and massof the times during these periods of transition.

consumption to an age focusing on a balance between the economy,

Our company started operation as Shibaura Machine Tool Co. in
December 1938 with capital investment of 10 million yen by Shibaura

environment, and society, with an aim to achieve sustainability, theSDGs, and the creation of a decarbonized society.
Our company is strengthening our efforts to contribute to theto meet wartime demands stemming from the Second Sino-world’s goals by solving these issues in our society through ourJapanese War which occurred during the early Showa period. Our

business activities.
Specifically, we will create and provide society with products,

machine tools, an area which other manufacturers were hesitant tosystems, and processes with the added value of “product + service”

enter. At the time the company was founded, our factory wasin areas such as energy saving, energy creation, energy storage,

located in the Tsurumi Plant of Shibaura Engineering Works Co.,

safety, productivity, and LCA, to help solve social issues, while

where the persons involved were passionate in their determination

increasing our own value at the same time, thereby making a lastingto establish the first factory specializing in large machine tools incontribution to society.
This technical report highlights some of the results of the

Shibaura Machine Engineering Review

2

Prepared Critiqueorigins lie in the successive introduction of various types of large

Patent News

Engineering Works Co. (predecessor of Toshiba Corporation) in orderJapan, flying to the U.S. and Germany to acquire technology andSeriesthe very beginning, while actively incorporating new technologies to

New Product

The business environment around us is dramatically changing, andTechnical Report

our parent company, Toshiba Corporation, in March 2017, changing

Technical Paper

Our company became independent from the Toshiba Group oftechnological developments we are working on. I hope this will
Introductory Noteprovide an opportunity for readers to understand Shibaura
Machine’s commitment to becoming integral to society, theenvironment, and our stakeholders, and our aim to work together tocreate value which will contribute to society. If so, this technology
report is one worth publishing. We hope you enjoy reading it.

Special Article
Technical Paper
Technical Report
New Product
SeriesPatent News
Prepared Critique3

Shibaura Machine Engineering Review

Special Article

Introductory Note

Slip Ahead

Special Article

Chairman

Yukio IIMURA

generally follows a process which starts off with planning, moves on

introduced, we drew two-dimensional maps with a drafter,

to determining specifications, developing conceptual and detailed

generated meshes, and then requested the Information Department

designs, and creating drawings, and concludes by verifying theto keypunch the massive amount of point group coordinate results

product’s performance. Evaluating strength is a critical factor withinfor calculation on a large computer at night when the processing

this process.

load was low. About one month passed between the start of drawing

I worked in the engineering field of injection molding machines

to output to obtain the results for one model. I remember thefor a number of years after joining the company, taking great careconstraint conditions were limited, and there were discrepancies

when handling fatigue fractures because a clamping force of 30 tobetween simulations and actual measurement values.

3500 tf is applied every cycle.

The first time I heard of the finite element method was about 44

used hydraulic clamping and had large internal-pressure containers.

research project analyzing the dangerous cross-section of gears

For small machines, an operating condition of two million cycles perusing the three-node triangular element method. I remember

year is common, which means ten to the seventh power of cycles

pulling my hair out because the simulation results of my self-madewill be reached in about five years. If the stress concentration area isprogram were the polar opposite of the measurement results

inside the internal-pressure container and the maximum stressobtained by the strain gauge. That nightmare-the discrepancy

value exceeds the fatigue limit, this creates a situation very much

between simulation and actual measurement values-had been

like a ticking time bomb as fatigue fracture may occur within five

reproduced in our company.
Later, Shibaura Machine was able to create point groups andwhich is the starting point of stress generation, is not constant, so

element data using 3D modeling and mesh generation functions,stress generation exceeding the elastic limit is completely out of theand gradually developed an interactive analysis environment using

question.

a dedicated computer. The use of triaxial strain gauges, which cancontainer was measured with more than 200 strain gauges at thecalculate the maximum stress value without considering the stress

Patent News

years after the machine is shipped. The size of the customer’s mold,

Seriesyears ago when I was a student and my professor had me work on a

New ProductAt that time, both small and large injection molding machines

Although stress around the periphery of the internal-pressure

Technical Reportdeal with a series of strength evaluation issues. When this was first

Technical Paper

When creating a new product, the development and design team

direction, has improved the accuracy of measurement values.
The introduction of 3D CAD since 1997 had a tremendous effectmeasurements on the inner side of the container, so designs wereon the development of electric injection molding machines, whichbased on actual results and empirical values accumulated over a

the Injection Molding Machine Division worked on as a last-ditch

long period of time multiplied with a large safety factor.

effort, while other companies were miles ahead in the transition

To solve this problem, Shibaura Machine introduced structuralfrom hydraulic to electric injection molding machines. The 3D CAD

analysis to some injection molding machines in the early 1980s to

system made it possible to seamlessly apply structural analysis to

Shibaura Machine Engineering Review

4Prepared Critiquedevelopment stage, it was extremely difficult to take actual stressIntroductory Note
Special Article

models drawn in 3D CAD, which significantly reduced development

hobbing machine”. The idea of this machine had been gestating

man-hours. The analysis of a stationary platen using conventional

since before World War II, and in October 1953, after the unsettlingsoftware required at least 80 man-hours, but with the new software,days during and after the war, we completed our first machine,

analysis could be completed in 8 hours, a reduction of analysis man-Japan’s first large precision hobbing machine, the HRS-500. This

hours to 1/10. Converting this reduction in analysis time alone into aultra-high precision machine eventually outclassed its competitors

launch schedule translates into a savings of two months for one

in Japan and abroad, and played a principal role behind the scenes

model and 14 months for a series of seven model changes.

in Japan’s continued dominance in the world of shipbuilding. In

The advantage of the new software is, while conventional

April 1964, the machine was awarded the Okochi Memorial

software required the designer to subdivide the mesh and makeTechnology Prize, and most recently, in 2009, the master worm

corrections for suspected areas where stress was concentrated, thewheel, which is the heart of the hobbing machine, was designatednew software automatically adjusts the shape function up to theas a Mechanical Engineering Heritage.

Technical Paper

ninth-order function while monitoring the convergence of the

The second wheel built into the first machine had a cumulative

calculation without changing the mesh, thereby increasing thepitch error of 49 μm to a diameter of 3400 mm (the table diameter

calculation accuracy.

was 5000 mm). Subsequent improvements in manufacturing andTechnical Report

The new software lowered the required level for analytical skills,

corrections to the wheel resulted in a cumulative pitch error of 4 μm

resulting in a considerable increase in the limited number ofin the seventh and final wheel (1970), an unprecedented degree ofanalysts. Indeed, the constant process of comparing calculation

accuracy. This error factor is so accurate that a bullet fired from theresults with actual measurements using hundreds of triaxial strain

Numazu factory at a clock with a diameter of 60 cm at Tokyo Station

gauges and then reviewing the differences by optimizing thewould land inside the dial. The advancement of measurement

constraint and boundary conditions is looped. As for materials,

technology through strong industry-academia collaboration andwhen casting materials are manufactured from end materials of

the development of cutting oils have contribution significantly toautomobile sheet metal, it is necessary to extract samples from large

the achievement of this accuracy.

New Productcasting materials and measure their substantive strength, and then

The historical story of our company and employees burning withreview allowable stress standards for spheroidal graphite cast irona sense of mission never fails to warm my heart. However, 17 longparts. In Digital Twin manufacturing, where manufacturing is carried

years passed between that first machine and the achievement ofout with the constant feedback of data and actual measurements, itthat performance in the final model.

Seriesis possible to systematically accumulate know-how on the types ofToday, half a century since that time, we must achieve a cumulative

dynamic loads and responses to singular points. If this loop can be

pitch error of 4 μm since the very first machine by adopting themaintained even if analysis software changes, quality can bepassion of our predecessors and using the latest technology, andguaranteed.

thereby inspire and earn the trust of our customers.

Patent NewsIn the development of electric injection molding machines at that

The key to achieving this is manufacturing by DX (digitaltime, motion analysis and interference analysis using mechanism

transformation) and Digital Twin. This idea is based on the concept

analysis with 3D CAD were effective tools for developers who usedof creating 3D CAD drawings and performing structural, mechanical,

the toggle mechanism for the first time in a clamping unit. I

thermal, vibration, and fluid analysis. In addition to this, if we areremember how impressed I was when the developer created aable to correlate an actual design with its digitally represented

linkage structure using 3D CAD and showed me an image where amodel twin and perform simulations in a virtual space, then we canlink worked using the motion function. This was 24 years ago.

analyze what will happen in the actual design and product.

Prepared Critique

Shibaura Machine excels in the development of specialized andIn this context, the most important thing from the viewpoint oflarge machines which other companies are reluctant to deal with.

our company’s know-how is the use of IoT to collect customer andOur mission is to contribute to key industries, and this is imprinted inlaboratory data and feed this back into the virtual space to improve

our very DNA.

the accuracy of the simulation. This is a method called model-based

An iconic example of this which comes to mind is the “master gear

5

Shibaura Machine Engineering Review

engineering or model-based design, which involves thorough front-loading. This method enables us to create an environment for agile
Introductory Notedevelopment.
Designers may be vaguely or clearly aware of insecure and vital
points during the product development stage, but if they pin theirhopes on a miracle with little evidence, they will not only burn theirfingers but also lose the trust of their customers.

Special Article

Why not we start with a thorough simulation of vital and insecure
points? I think such a simulation will help us build a trusting
relationship with our customers where we can engage in databased, guarantee-based conversations or even delve into proposed
processing methods.
Companies must be able to respond quickly and easily to issues

Technical Paper

which are in line with the trends of the times, such as dramatically
improving production efficiency with built-in systems andimproving LCA (life cycle assessments), including decarbonization.

Technical Report
New Product
SeriesPatent News
Prepared Critique

Shibaura Machine Engineering Review

6Special Article

Introductory Note

DX by the New "Shibaura Machine"

Special Article
Technical Paper

1

Director and Executive
Operating Officer

Research & Development Center,
DX Promotion Project

Akiyoshi KOBAYASHI

Hiroyuki MAEHARA

indicates the following two points are required to achieve DX.

Introduction

1) Eliminate the black box status of existing systems to make full use

The Ministry of Economy, Trade and Industry (METI) studied theof data.

Technical Reportactions which Japanese companies should take and the measures

2) Introduce digital technology and promote the creation of newwhich the government should take in order to accelerate the digitalbusinesses and global expansion with digital native humantransformation (DX) of Japanese companies, and published an

resources playing a leading role.

interim report on December 28, 2020 as “DX Report 2” . In September

The report shows a strong sense of crisis that Japan will become a2018, METI published “DX Report: Overcoming of ‘2025 Digital Cliff’loser in the competition in the digital world if it lags in its efforts to

Involving IT Systems and Full-fledged Development of Efforts inutilize data while European and U.S. platformers are expediting theDigital Transformation”2) and has been developing measures toability of businesses to make full use of digital data.

1)

New Product
Seriespromote DX. Nearly three years have passed since then, and theWhen people talk about DX in the manufacturing industry theuncertainty surrounding the corporate environment has steadily

focus is on improving the efficiency and productivity of production

increased due to circumstances such as the COVID-19 pandemic,

sites through technologies such as IoT and AI. However, the heart ofamong others.3) The “DX Report” released in 2018 states it is

DX is not there. It is said DX is a shift in business model fromunderstood DX is essential to promote the creation of new business“manufacturing, providing ‘products’, and getting paid by customers”

models which use digital technology to enhance future growth andto “providing ‘services’ and creating value together with customers

competitiveness. However, the following three issues were pointed

to increase the value of their experience”.4)

out as obstacles to its realization.
1) Existing systems are built for each business division, so they are
not able to utilize data across the entire company.
2) Existing systems are built with excessive add-ons and customi-

In the midst of such movements, in April 2020, we changed our
corporate name from Toshiba Machine to Shibaura Machine and set
forth a new long-term vision. We below describe the DX to which weare aiming.

Patent News

zations onto standard systems. As a result, existing systems arecomplicated and black-boxed.
3) There is strong resistance by people in the field against therevision of existing systems or review of operations for data

Prepared Critiqueutilization.

2

Shibaura Machine’s Approaches to DX

2.1

Long-Term Vision and the Mission of the
R&D Center

The report further points out, if we cannot overcome these

On February 4, 2020, we announced our “Long-Term Vision 2030

challenges, we will not only be unable to achieve DX, but also will

(Our Ideals)”, which is to “achieve both resolving of social issues andface the possibility of significant economic losses in 2025 andenhancing corporate value by responding to the megatrends facing

beyond, which is described as the “digital cliff of 2025”. The report

the global manufacturing industry with outstanding technological

7

Shibaura Machine Engineering Review

innovations”. In the future, we will respond to megatrends (climate

2.3

change and resource scarcity, changes in population structure, and“Shibaura Machine must become a manufacturer which flexibly

advancements in technology, among other things) through techno-

and quickly responds to the need for Engineer-to-Order (ETO)

logical innovations (monetization of processes and knowledge,

manufacturing with connected machines”. In order to make ETO-

breakaway from in-company management, and enhancing M&A) in

based machines a pillar of profit, the R&D Center aims to build

the form of added value of “product + service”.

“ultimate manufacturing of products at high productivity with ETO”,

R&D Center's Goal : "DX for Technology"

establishment of the R&D Center, which will serve as the core forgroup which can respond to megatrends in the global manufacturing

technological development, and will lead the company’s

industry by achieving “high completion degree of a product at thetechnological development in terms of both software and hardware

design stage”, “highly efficient production”, and “quick delivery ofwith the three missions shown in Fig. 1.

high value-added ETO-based machines”. To achieve this goal, theSpecial Article

and then further aims to transform the company into a corporate

Introductory Note

One of the management reform plans to achieve this goal is thecompany is working on two reforms: “DX for enhancement ofshown in Fig. 3.

2.2

Technical Report

Fig. 1

Technical Paper

commodity power” and “DX for improvement of productivity”, asMissions of the R&D Center

About SHIBAURA DX

One of the missions of the R&D Center is to “promote digitization/

Fig. 3

Transformation brought about by SHIBAURA DX

strategy for manufacturing.
In DX, digitized data is of utmost importance. By acquiring dataon all kinds of things, sharing and analyzing the accumulated data,
and utilizing the simulation results, it is possible to reproduce what

2.3.1

New Productdevelopment standardization” to realize SHIBAURA DX, our DX

Transformation 1 : DX for Enhancementof Commodity PowerThe point of Transformation 1 is the digitization of the development
and design process.

“virtual”) (Digital Twin). With digital data, it is even possible to realize

throughout the entire process, information from inside and outside

a virtual space where the skills of master craftsmen are reproduced

the company can be linked, machine performance, costs, and(digital triplet). This is the goal of SHIBAURA DX: to enable simulationdelivery dates can be grasped in a timely manner without the need

not only in design, but also in all scenes of manufacturing andto create drawings, and planning, manufacturing, sales, and service

maintenance, thereby creating products which have never existed

can be addressed, even for requests for ETO-based machines. Similar

before and producing new value for customers.

work can be completed in a shorter time, allowing more focus on

Patent News

By using digital data of 3D models which can be analyzed
Seriesexists in the real world (which is “real”) in the digital space (which is

Prepared CritiqueFig. 2SHIBAURA DX for manufacturing

Fig. 4

Manufacturing realized with digital information

Shibaura Machine Engineering Review

8Introductory NoteFig. 5Overall image of MBD (above figure) andoutline of approaches (right figure)Special Article

creating new value for customers.

3

Sustainable Future and SHIBAURA DX

this goal. This technique is used for modeling with 3D digital data,

3.1

How Does DX Relate to the SDGs?

automation of boundary conditions through thorough simulation,

Even more than “DX”, the “SDGs” are increasing their presence as

Model based development (MBD) is the technique for achieving
Technical Paper

FEM analysis of the entire machine, and coupled analysis of strength,mechanism, and heat transfer, among other things, with the aim ofeliminating prototypes.(Fig. 5)

keywords in business.
While tackling the SDGs leads to a sustainable society and thereby
contributes to the public good, at the same time it has the added

Technical Reportbenefit of reducing costs due to increased efficiency and sustaining

New ProductTransformation 2 : DX for Improvementof Productivity

business with profits in compensation for providing value to

The point of Transformation 2 is digitization of business processes.

Therefore, the relationship between DX and the SDGs is of great

In order to make digital data usable throughout the entire process,importance, not only introducing the latest technologies when

it is essential to digitize information and comprehensively manage

promoting DX, but also in examining how and what we want todata (base) in a highly productive manufacturing infrastructure. Intransform.

2.3.2

customers. The realization of DX can be a means to that end.

this case, data is connected like a thread, and the data created in theIt can be said DX has a significant role to play in achieving the

upstream process is utilized in the downstream process (digital

SDGs by designating goals for the realization of a sustainable

thread).

society.

Series3.2

Contribution to Decarbonization and
Resolution of SDG Issues

As global sustainability is now being actively considered, and as
the world has begun feeling the length of a time axis extending
Patent News

Fig. 6

Digital thread

beyond one’s own life into the future, customer value standards arealso changing. The significance of company efforts to realize

2.3.3 SHIBAURA Virtual Lab
We are planning to establish the SHIBAURA Virtual Lab with ashowroom in the Sagami Plant as a base for “providing services”. To

Prepared Critiquerealize SHIBAURA DX, the Lab will play a role as a base for researchand development equipped with the most advanced environment,
as a creative office for remote work, industry-academia collaboration,and IoT/AI utilization, and as a value co-creation base for creating
new values with our customers.

9

Shibaura Machine Engineering Review

sustainability is dramatically increasing.
Fig. 7 shows the direction of Shibaura Machine’s efforts towardsustainability, and Fig. 8 shows the overall image of the efforts.

Machine’s approach to DX and how it clearly is related to ourour specific initiatives. We hope this will help readers understandthe new Shibaura Machine, lead to creation of customer value, andhelp us receive advice from the customer’s perspective.

Introductory Notecontribution to the SDGs. This technical report gives you some of

DX will transform a company’s products, services, and businessDX holds the promise of changing the market structure itself andsolving social issues. The transformation into a sustainable society
Fig. 7

Shibaura Machine's efforts toward sustainability

can use DX to create a so-called ecosystem which goes beyond theSpecial Article

models through the use of digital technology and data. Meanwhile,

company’s borders to reform the value chain. While realizing DX,
Shibaura Machine will continue to contribute to the solution ofTechnical Paper

social issues.

References
1) https://www.meti.go.jp/press/2020/12/20201228004/20201228004.html
2) https://www.meti.go.jp/shingikai/mono_info_service/

Fig. 83) Isao FUKUMOTO, “Explaining the DX Report 2. Two years since theOverall image of the efforts to achieve SDGs

‘Digital Cliff of 2025’. What is the current situation of domestic
We will make efforts on development to solve social issues, starting

companies? and what will become of them?”, installment datedwith the SDGs, and aiming at future-oriented manufacturing.(Fig. 9)

January 19, 2021 in the series “Essay on Business Practices for the44) Source: Isao FUKUMOTO, Keiichiro NABENO, Tomoki KOSAKA,

Conclusion“Digital First Society”, Nikkan Kogyo Shimbun, 2019.

New Product4th Industrial Revolution” in “Business + IT”, SB Creative.

Technical Report

digital_transformation/20180907_report.html

In the above we have introduced an overview of Shibaura

SeriesPatent News
Prepared CritiqueFig. 9Aiming at future-oriented manufacturing

Shibaura Machine Engineering Review

10Technical Paper

Introductory Note

Research of Optimized Grease Film on Sliding Surfaces
In this research, we confirmed it is possible to estimate the lubrication film thickness on asliding surface based on the dimensionless central film thickness formula in EHL theory and byadditionally applying the grease film thickness and the correction formula for temperaturedependence of oil viscosity. Based on the above, we identified the conditions for achieving stable

Special Article

lubrication film with appropriate surface roughness under a specific range of material, contactpressure, and sliding speed. This confirmed the possibility metallic material, such as spheroidal
graphite cast iron, which we did not use for the sliding surface, can be used.

Research & Development Center
Research & Development Department

Hiroyuki ONUMA

Technical Paper

1

Introduction

Shibaura Machine manufactures industrial machinery havingof lubricants and the possibility of selecting different materials.

2

EHL Theory

functions. Those sliding surfaces are often made of copper alloy

2.1

Oil Lubrication

which can resist damage and they are lubricated with oil or grease.

The EHL theory was established based on a great deal of research

In addition, most of Shibaura Machine products are large machines,

and is described in various types of literature, and therefore, detailed

and their principal structural parts are frequently made of spheroidal

explanation of the EHL theory is omitted. In brief, EHL theory is usedgraphite cast iron, which has strength and toughness and can befor calculating the thickness of oil film accompanied by elastic

produced in-house.

deformation of the contact surface based on the Reynolds fluid-film

sliding surfaces which allow rotation, direct advance, etc. to achieve
Technical Report
New ProductResponding to a recent trend, Shibaura Machine is striving to takelubrication theory which considers viscosity of lubricants, and EHL

measures to reduce environmental loads with the aim of achieving

theory is suitable for studying the lubrication state in cases when

the SDGs and considers it a mission to provide environment-loads are concentrated in a small area of contact.

Seriesconscious products through corporate activities. As part of thisIn the wear test, a point contact occurs on the sliding surface

effort, it is important to take measures to reduce the use of lubricants

when viewed from a micro perspective. As a basic formula, theand adopt materials with low environmental loads. Whenformula (1) for obtaining the dimensionless center film thickness

considering the environmental load unit of copper alloy and castresulting from the point contact, which is referred to as “Hamrock-iron, the CO2 emission intensity of copper alloy based on physicalDowson formula”, is used.

Patent News

quantity is 4.49 tons, and the CO2 emission intensity of cast iron is(1)

3.49 tons which is lower than that of the copper alloy. Since cast iron

where G denotes a material factor, U denotes a speed factor, W

is produced in-house, CO2 emissions which occur during thedenotes a load factor, and k denotes an ellipticity of contact ellipse.

transportation of parts can be reduced.

G, U, and W are expressed as shown below.

Conventionally, contact pressure and PV value loads are mainly
evaluated at the design phase of the sliding surface. However, by
evaluating sliding properties according to the lubrication state of the

Prepared Critiquesliding surface, it may be possible to reduce the use of lubricants andadopt cast iron. In this research, we estimate the thickness of

α : Pressure viscosity coefficientlubrication film on the sliding surface based on the ElastoHydro-

E’ : Equivalent elastic coefficient

dynamic Lubrication theory (hereafter, referred to as “EHL theory”)

η0 : Normal-pressure base oil viscosityand by performing experiments, and we confirmed the optimizationu : Flow rate of lubricant

11

Shibaura Machine Engineering Review

3.1.2 Wear Test

w : Normal direction load

To confirm the galling properties of metallic material, we used aThis applies to cases where lubricants are oil. As for grease,
explanation will be given in the next section.

pin-on disk scuffing tester. Fig. 2 shows a schematic diagram. Thismachine is designed such that a pin test piece is pressed onto a disk
test piece by a pneumatic cylinder and the disk test piece is rotated.

2.2

Grease Lubrication

Introductory Note

R : Axial equivalent curvature radius

Using this machine, the amount of wear and friction force during

formula (2) based on the measured value has been established.1)

operation were measured as the scuffing properties of the material
by means of a displacement gauge and a load cell provided on the(2)

handgrip portion of the pin test piece. Temperature of the pin test
piece was also measured by a thermocouple.

Special Article

Concerning the thickness of grease lubrication film, a regression

Hg : Dimensionless grease film thickness
Hoil : Dimensionless base oil film thickness obtained
Technical Paper

by the formula (1)wherein,

The following are physical properties of grease:

Schematic diagram of the pin-on disk scuffing testern : Exponent

3.2 Measurement of Film Thickness
3.2.1 Conditions for Film Thickness Measurement

hoil : Center film thickness

To measure the film thickness, we used a chrome-coatedk2 : Plastic viscosity

Using these properties, the thickness of lubrication film on thesiliconized glass disk and a steel bearing ball. In addition, themaximum surface pressure was set to 0.55 GPa, and rolling speed
was changed within the range between 0.002 m/s and 1.0 m/s. We

3Experimentused grease containing lithium-based or urea-based thickening

New Productsliding surface is obtained.

Technical Report

Fig. 2

k1 : Viscosity of base oil

agents to measure the thickness of lubrication film.

3.2.2 Measurement Results

To measure the thickness of grease film, we used an EHL oil film

Fig. 3 shows the relationship between the ratio of the measured

thickness measuring instrument which is based on opticalfilm thickness to the theoretical film thickness, obtained by formulasinterferometry (Fig. 1). In this method, a steel ball is pressed onto the(1) and (2), and the rolling speed. It also shows the image of changes

surface of the glass disk coated with grease and rotated, and thenin theoretical film thickness according to the rolling speed.

Series

3.1 Experimental Equipment
3.1.1 Film Thickness Measurement Test

the thickness of generated lubrication film is measured. In addition,
Patent Newsby changing the rotation speed, the thickness of lubrication film at
each speed was measured.

Prepared CritiqueFig. 1EHL oil film thickness measuring instrument

Fig. 3Results of film thickness measurement

Shibaura Machine Engineering Review

12Introductory NoteFig. 4

Measurement results of wear test (copper alloy)

Special Article
Technical Paper

Fig. 5

Measurement results of wear test (spheroidal graphite cast iron)According to Fig. 3, the ratio of the measured EHL film thickness to

3.3.2 Measurement Results

Technical Report
New Productthe theoretical film thickness is around 1 at the rolling speed of 0.02

Fig. 4 and Fig. 5 show the measurement results when copper alloym/s or higher. This indicates the measured film thickness is almostand spheroidal graphite cast iron were used. The friction force andthe same as the theoretical film thickness. However, at rolling speeds

temperature of both materials are stable at low surface pressure.

of 0.01 m/s or lower, the ratio of the measured film thickness to the

However, the friction force of copper alloy became significantly

theoretical film thickness is more than 1. This indicates the actual

disordered in the latter part of the surface pressure of 25 MPa, andfilm thickness tends to become thicker than the theoretical filmthat of spheroidal graphite cast iron became disordered at the

thickness. It is considered necessary to review the theoretical film

surface pressure of 120 MPa. Accordingly, temperature also increased.

thickness at a low-speed range.

Fig. 6 shows the results of observing the spheroidal graphite cast irontest piece at that time by means of a SEM. According to the SEM

3.3 Wear test
3.3.1 Conditions for wear test

images, the spheroidal graphite exposed on the surface of the pin

Thermally-refined chrome molybdenum steel disk test pieces,indicates abrasive wear resulting from contact is occurring.

test piece is missing, and scratch-like streaks can also be seen. This

Seriesspheroidal graphite cast iron pin test pieces, and copper alloy pin
test pieces were used for the test.

According to the measurement data, disorder of the friction force
and the increase of temperature in copper alloy occurred at lower

Rotation speed of the disk test piece was set to 180 min , andsurface pressure when compared with spheroidal graphite cast iron.

surface pressure was changed step by step within a range between

During testing, as the surface pressure increased, metal contact

2.7 MPa and 280 MPa by changing the pressing force by means of anoise, vibration, etc. were greater in spheroidal graphite cast iron.

-1

Patent News

pneumatic cylinder.
As a lubricant, lithium-based grease was applied to the disk test
piece. In addition, to uniformize the lubrication state under eachsurface pressure condition, grease was applied to the disk test piece

Prepared Critique

every time the surface pressure condition was changed.
This research was not conducted to observe the degree ofprogress of wear occurring between metals. However, it is importantto prevent the occurrence of wear and adhesion, so we measured
the friction force and temperature. (Fig. 2)

13

Shibaura Machine Engineering Review

Fig. 6

Observation of the surface of the pin test pieceConsideration

4.1

Grease Film Thickness

4.2

Wear Test

Based on the results of the wear test, we confirm the lubrication
state using the film parameter under each condition as an index.

A gap between the theoretical film thickness and the measured

Generally, the film parameter is expressed by the ratio of the

EHL film thickness at rolling speeds of 0.01 m/s or lower results fromtheoretical film thickness to the standard deviation of composite

the composite effects of viscosity change and the deposition of theroughness of root-mean-square roughness of each surface (4).
(4)

In the above-mentioned Hamrock-Dowson viscosity formula (1)Because composite roughness is a standard deviation, the height

being constant. This means the base oil of grease is considered as aof roughness protrusion is 3 (3 sigma) or less, and two planes are

Newtonian fluid. It is well-known the viscosity of grease is close tocompletely separated by the lubrication film when Λ > 3. This state

the viscosity of base oil at high shear rates, and grease is consideredis referred to as “fluid-film lubrication”. When Λ < 1, two metal planes

to be a non-Newtonian fluid whose viscosity changes as the shear

interfere with each other almost 100% and this state is referred to asrate increases.

“boundary lubrication”. In addition, in-between the lubrication state

Change of viscosity of non-Newtonian fluid can be obtained byis referred to as “mixed lubrication”.

Technical Paperand the regression formula for grease (2), viscosity is regarded asSpecial Article

grease thickening agent.

Introductory Note

4

The lubrication state estimated from the film parameter isthe Carreau-Yasuda viscosity formula (3).

described in the test results shown in Fig. 4 and Fig. 5. Herein, in thecalculation of the theoretical film thickness, the Waslter-ASTM
formula was used to correct the temperature dependence ofη∞ : Infinite shear viscosity

viscosity. According to Fig. 4 and Fig. 5, in the area of fluid-film

γ : Shear rate

lubrication, the friction force of both copper alloy and spheroidal

α : Pressure viscosity coefficientgraphite cast iron shows stable behavior, and in the area of mixed

λ : Time constantlubrication where both surfaces start to come in contact with each

Formula (3) is applied to the theoretical film thickness included inother, the friction force becomes disordered and temperature

the results of film thickness measurement mentioned above. (Fig. 7)

increases. This indicates it is important to check the film parameter

New Productη0 : Zero shear viscosity

Technical Report(3)at the design phase and determine necessary surface roughness.
When compared with spheroidal graphite cast iron, the friction
force of copper alloy fluctuated at lower surface pressure. Becausepressure increased, scuffing may not easily occur even though wear

Seriescontact noise and vibration did not change even when surface

progresses.

Fig. 7 Results of film thickness measurement(correction of non-Newtonian fluid)

Conclusion

Patent News

5

We obtained the following findings from this research:a) We have confirmed it is possible to estimate the lubrication state
by focusing the thickness of grease lubrication film based on the

thickness to the theoretical film thickness in the low-speed range is

EHL theory and by use of the correction formula for temperature

close to but more than 1. This results from the deposition of thedependence of viscosity.

grease thickening agent on the contact surface. This indicates urea-b) It has been clarified the evaluation using the film parameter at thebased grease forms thick film in the low-speed range where the EHL

design phase is effective. Also, the design criteria for determining

film becomes thin.

surface roughness has been clarified.

Shibaura Machine Engineering Review

14

Prepared Critique

When urea-based grease was used, the ratio of the EHL filmc) Urea-based grease is effective depending on the sliding speed
Introductory Notefrom the aspect of forming appropriate film thickness.
d) We have confirmed the possibility spheroidal graphite cast iron,etc. can be applied to the sliding surface of industrial machinery.
The remaining issue is to confirm a material use limit for eachsurface roughness from the aspect of the PV value of the sliding

Special Article

surface.

References
1) Tsuyoshi Kochi, Ryosuke Ichimura, Michitaka Yoshihara, Daming
Dong, and Yoshitsugu Kimura, “Film Thickness and Traction in SoftEHL with Grease”, Tribologist, 61, 12 (2016), 874.

Technical Paper
Technical Report
New Product
SeriesPatent News
Prepared Critique
15

Shibaura Machine Engineering Review

Technical Paper

Research & Development Center
Research & Development Department

Research & Development Center
Research & Development Department

Research & Development Center
Research & Development Department

Research & Development Center
Research & Development Department

Kazuhiro FUKADA

Satoshi FUKUYAMA

Takeshi NAMBA

Yoshiaki KURIHARA

Rintaro SUEKI

process conditions. The plasma generator has an advantage in film formation on a resin molded product because theworkpiece is not easily damaged and a thicker SiO2 film can be formed with a short tact due to the high plasma density.

Technical Paper

We developed a head-up display (HUD) mirror film deposition system and utilized CAE gas-fluid analysis to optimize

Special Article

Research & Development Center
Research & Development Department

Introductory Note

Development of PVD + CVD Vacuum Integrated System ; Application to
Moisture-Resistant Multilayer Reflective Film for Heads-up Display Mirror

Due to these advantages, the plasma generator can be applied not only to HUD mirror film formation, but also to AR
coating and hard coating, among other things.

Introduction

modification and polymerization and the sputtering zone for forming
metal film are integrated in one treatment room. In the conventional
vacuum deposition system, the treatment room is evacuated for amachines by applying decoration and adding functionality bylong period of time to generate a high vacuum condition before themeans of various types of surface treatment. Recently, not only

process starts. However, to link the tact time with the injection

metal film decoration applications but also techniques whichmolding machine, our newly developed deposition system has

provide functional film properties have become indispensable inachieved a process which can satisfy required performance in thevarious fields including optical, medical, biotechnology, electronics,

medium vacuum area which is generated in a significantly reduced

and automobile industries.

exhaust time. Features of this deposition system are below described.
① This is a vacuum integrated deposition system with a processing

system as a turnkey system which can be functionally interconnectedchamber consisting of two zones to enable the plasma treatment

with a molding machine. Generally, the vacuum deposition systemand the sputtering process.

requires long tact time and sometimes causes the deterioration ofquality resulting from the stock of molded products. Herein, we will

② When compared with conventional vacuum deposition systems, it
is possible to achieve significantly higher productivity.
③ It is possible to form film on resin because thermal load is small.

system which can form high-quality film in the medium vacuum④ It is possible to achieve high-quality plasma polymerization andarea with very short tact time which cannot be achieved byhighly efficient plasma modification by use of newly-structured

conventional vacuum deposition systems. We will also report aboutplasma electrodes.
⑤ It is possible to perform high-quality vacuum deposition without

Deposition System

The newly developed vacuum integrated deposition system is so
designed so the plasma treatment zone for performing surface

resin molding process.

2.1

Basic Principles

Basic principles of plasma treatment and sputtering technique will

Shibaura Machine Engineering Review

16

Prepared Critique

being affected by gas generated from resin immediately after the2

Patent News

report about the development of the vacuum integrated deposition

the application of this new system to form optical film.

SeriesShibaura Machine has recently developed a vacuum deposition

New ProductFinished molded products are manufactured by injection molding

Technical Report1be herein described. As shown in Fig. 1, by applying high-frequency
Introductory Note

voltage to gas present between electrodes, electrons collide with gas
molecules, thereby generating plasma.

Referred from the Automobile Glossary
Special Article
Example of display on the HUD
Referred from Panasonic website
Technical Paper

Fig. 1

Fig. 3

PlasmaGenerated plasma has significantly high energy which enables highquality polymerization and surface modification.
As shown in Fig. 2, sputtering is a dry plating technique whereintarget metal for forming thin film is placed in a vacuum chamber, theHead-up display

Technically, the HUD is required to display more information at highluminance without strain, and it is necessary to increase the size of
two reflection mirrors loaded on the HUD and achieve high reflectanceand low strain.

Technical Reporttarget metal is bombarded with a rare gas element (argon etc.) ionized

The reflection mirror of the HUD is metal reflective film created byby high voltage, causing metal atoms to be removed from the target

forming metal film on PC (polycarbonate) of the substrate. Higher

metal surface and reach the substrate, thereby forming film.

reflectance can be achieved by use of enhanced reflective film in whichlayers of film having different refractive indexes are laminated (Fig. 4).

New Product
SeriesFig. 2

3

Sputtering

Application of the New System to
Optical Parts for Automobiles

Fig. 4

Enhanced reflective film

To achieve high productivity, the vacuum deposition system

Patent News
Prepared Critique

As a turnkey system made by Shibaura Machine, we focused mirror

developed for the HUD is a carousel type system consisting of two-

(optical film) for the heads-up display (HUD) (Fig. 3) and studied thetarget magnetron sputtering equipment loaded with metal targets,enhanced reflective film formed by the vacuum deposition system oni.e. aluminum (Al) and niobium oxide (Nb2O5), and plasma electrodes

the surface of high-quality molded products manufactured by thewhich can form SiOx overcoat by plasma-enhanced chemical vapor

injection molding machine.

deposition (P-CVD) using HMDSO as raw material. It is possible toproduce high-quality mirrors with high reflectance and less strain by

3.1

Background of Development

In many countries, there have been moves to mandate the installationof a HUD in new cars, which will likely result in future market growth.

17

Shibaura Machine Engineering Review

means of vacuum integrated treatment of the enhanced reflective
film formed by the lamination of Al, Nb2O5, and SiOx film generated
by sputtering and SiOx overcoat.

types of targets requires an individual power source; however, in theConsidering the solution to the above-mentioned issues and the

SiO2 film, and as for the Nb2O5 film, oxygen-deficient Nb2O5 to which afuture scalability, Shibaura Machine developed a vacuum deposition

DC power supply can be applied is used as target material. As a result,

system having features as below described.

the number of power sources can be reduced, which reduces cost.

• Vacuum integrated system which combines magnetron sputtering

Shibaura Machine process, the CVD technique is adopted to form theIntroductory Note

System (Structure, Specifications,Features, etc.)

3.2

This system is capable of using more than three kinds of material toform film, and also forming film other than SiO2 film by the new• Adoption of high-density plasma electrode CVD to form film with aplasma generator CVD system, and further performing chemical

low refractive index;

decoration using O2 gas, N2 gas, H2 gas, etc. It is also possible to• Reversal mechanism type two-carousel system to perform auto-

increase adhesion of the HUD mirror thin film by performing chemicalmated operation between the injection molding machine and thedecoration on the surface of the injection molding material.

Special Article(2 targets) and CVD processes;

deposition system;

3.3

D125 mm (18 combiner-type workpieces can be loaded).

At the design phase of the vacuum deposition system we

Design and Improvement using CAE

performed fluid analysis of the plasma condition which could

least 90% in the visible-light area. Generally, such film is formed bygreatly affect CVD, including; diffusion, heat, and mass partial ratio,

combining three types of optical thin film, which are metal film, film

and analysis of the magnetic field of the magnet for the sputteringwith a low refractive index, and film with a high refractive index,

process so as to achieve an efficient system most suitable for theformed on a polycarbonate molded product. Shibaura Machineprocesses. Herein, the gas-fluid analysis will be described in detail.

adopted Al (DC sputtering), SiO2 (CVD) and Nb2O5 (DC sputtering) for

Technical Report

The HUD mirror requires the formation of film with reflectance of atTechnical Paper• Maximum dimensions of target workpiece: L400 mm × W200 mm ×

the film, respectively. The reason for this is if three types of film areformed by a sputtering technique, an RF method needs to be
New Productperformed for SiO2 and Nb2O5, and accordingly, each of the three

SeriesPatent News

Fig. 6

Analysis of gas flow in the chamberpressure (medium vacuum) conditions both in the case where thecarousel rotates and where the carousel does not rotate. Fig. 6
indicates material gas is efficiently fed to the products placed in theFig. 5 Vacuum deposition system for HUD

carousel by rotating the carousel.

Shibaura Machine Engineering Review

18

Prepared CritiqueFig. 6 shows the results of analysis of feed gas flow under processfilm were formed using the same recipe, all the batches satisfied theIntroductory Note

reflectance standard. In addition, in the constant-temperature highhumidity test, reflectance of the HUD mirror thin film is within thestandard, which indicates the mass production criteria can be satisfied.

Fig. 7 Analysis of CVD feed material in the chamber
Special Article
Technical Paper

Fig. 8 Analysis of CVD feed material in the raw material feed unit

In the CVD, SiOx film is formed by means of the reaction of oxygen
radicals generated by using raw material and plasma. To form desired

Fig. 9SiOx film, it is necessary to uniformize the mass ratio of oxygen

Comparison between the SiO2 film thickness and the mass partial ratio of
precursor gas

Technical Report

radicals which react with the material. Fig. 7 and Fig. 8 show the resultsof calculating the mass partial ratio in the chamber and in the raw
material feed unit. At the initial development phase, large reflectance
distribution in the vertical direction according to location was
confirmed on the samples placed in the carousel. As shown in Fig. 9,

New Productresults of analysis of the mass partial ratio in the chamber supported
the distribution of mass partial ratio of actual samples. Thus, by
optimizing the raw material feed unit which affects the distribution in
the chamber based on the analysis results, the distribution has beensuccessfully improved.
Fig. 10

Series3.4

Results (Performance Evaluation and
Trial Production Results)

4

Reflectance of HUD mirror

Conclusion

Patent News
Prepared Critique

The HUD mirror film was formed on a polycarbonate substrate under

Unlike general plasma generators, the plasma generator adopted

the SiO2 film formation conditions optimized based on the above

for this system does not easily cause damage to the workpiece andresults, and the reflectance was measured. Fig. 10 shows the results.

it is therefore advantageous in forming film on resin which tends to

In Fig. 10, the horizontal axis indicates wave-length and the vertical

deteriorate. Since plasma density is high, it is possible to form thickaxis indicates reflectance. The black line indicates sample film formed

SiO2 film with short tact time. With these advantages, the plasmaon the upper stage, the blue line indicates sample film formed on thegenerator can be applied not only to the formation of HUD mirror

middle stage, and the red line indicates sample film formed on thefilm, but also to AR coating, hard coating, water-shedding coating,lower stage.

among other things.

As shown in the drawing, the general reflectance standard of the
HUD mirror (reflectance of 90% between the wave length of 450 nm

References

and 650 nm) has been achieved in the sample film formed on the

Patent number

Patent registration No. 6625728

upper, middle, and lower stages of the carousel. When 30 batches ofTitle of invention

Plasma generator

19

Shibaura Machine Engineering Review

Technical Paper

Twin-screw extruders are very versatile continuous polymer processing machines which
contribute to both energy and environmental conservation and make it possible to manufacture
many kinds of plastics. This article reports the study on numerical analysis to grasp phenomena

Introductory Note

Numerical Analysis on an Extrusion Process in a Twin-Screw Extruder

and increase efficiency in an extrusion process. This article is a summary of the doctoral dissertation

Metal & Plastics Industrial Machine Company
Extrusion Machine Engineering Department

Masatoshi OHARA

Introduction

analysis for the purpose of improving product quality, reducing
waste of raw materials, and shortening development lead time.
In this study, 2.5D FEM, which has been developed in the injection

consumer attention in the fields of energy and environment. The Co-

molding CAE field, was applied to the Twin-Screw Extruder toRotating, Fully Intermeshing Twin-Screw Extruder TEM Series, which

propose a practical solution to the simulation of a flow of resin, andShibaura Machine manufactures and sells (hereafter called the Twin-then comparison and verification were made through experiments

Screw Extruder), is mainly used to process or manufacture plastics.

in cooperation with HASL Co., Ltd.

The Twin-Screw Extruder is an extrusion molding machine equippedwith screws featuring especially high kneading performance andversatility. The Twin-Screw Extruder is configurable in an almost

2

Technical Report

In recent years, plastics are attracting both producer andTechnical Paper

1

Special Article

the author wrote when completing the doctoral course at Kanazawa University.

TheoryThe Twin-Screw Extruder is conventionally analyzed only bythese key components are modularized. Fig. 1 shows typical screw

means of 1D FAN and 3D numerical analysis. 1D FAN is a method ofelements.

quickly calculating a leveled fill ratio and pressure distribution in the

New Productinfinite combination of screws and barrels particularly because

axis direction of the screw across the extruder by factoring screw
shapes. Also, 3D numerical analysis is a process of performing
physical calculation in detail by three-dimensionally discretizing

model is applied. The Hele-Shaw flow model is a two-dimensional
Fig. 1Screw elements

Seriesfluid resin into grids or particles. In this study, the Hele-Shaw flow

flow of incompressible resin in a thin layer, and predominantly
affected by viscosity. This article will propose an approach of

to a wide variety of materials, but to achieve superior kneading

efficiently calculating the fluidity of resin not only in the axis

performance, it is necessary to design and select the most suitabledirection but also the circumference direction of the screw acrossconfiguration for materials and specifications. In such a configuration

the extruder. Fig. 2 illustrates the overview of the configuration ofPatent News

These characteristics allow the Twin-Screw Extruder to be adaptable

design process, a trial-and-error approach is conventionally taken so
the mix of raw materials, screw configurations, and operating
Prepared Critiqueconditions are adjusted to achieve the desired product quality.
However, from the perspective of the fields of energy andenvironment, demand for product development has been increasing
in recent years. Therefore, it is desirable to establish a configuration
design process of the Twin-Screw Extruder based on theoreticalFig. 2Hele-Shaw flow model in the Twin-Screw Extruder

Shibaura Machine Engineering Review

20Introductory Notethe Twin-Screw Extruder considered in the analysis.

of resin pressure distribution. The flow channel at the exit of the

In Fig. 2, r represents the direction of the radius of the screw, z theTwin-Screw Extruder was narrowed to make resin reside. Thenaxis direction, θ the rotational direction, RS the radius of the screw,pressure caused by the flow of resin was measured using a pressure

and Rb the radius of the barrel. The equation below is true on thegauge.

screw surface.

In the experiment, homo polypropylene (F-704NP, MFR 7.0g/10min,
prime polymer) was used. Also, a rheometer (MCR 302, Anton Paar)

Special Article

In the equation, vθ and vz represent the flow velocity in the θwas set up to measure the viscoelasticity of the material used in the

direction and the z direction respectively. In addition, assuming theanalysis. The fitting of the obtained complex viscosity data wasrelative velocity of the barrel with respect to the rotating screw is Ω ,performed using the Cross Model, constitutive equation of viscosity.

the following equation is true on barrel surface Rb .

In addition, TEM-26SX (L/D=64) was used in the experiment. Fig. 4
illustrates the screw configuration and the positions of pressure

Applying the Hele-Shaw flow model results in v r = 0 . Also, vθ andgauges used in the experiment. (See 1, 2, 3, and H in the figure below.)

Technical Papervz are functions of only r . Since the flow velocity in the direction of
the normal is ignored, the number of variables necessary forcalculation is reduced, and consequently, a time for calculation isshortened.
2.5D FEM discretizes two adjacent cylindrical columns into finite

Fig. 4

Device configuration

Technical Report

elements along the outsides of the screws as shown in Fig. 3. Where

Fig. 5 shows the results obtained when pressure at the exit was

the elements of the two cylindrical columns overlap, the flow ofincreased up to 5.5MPa with a throughput of 10kg/h and a screw

resin between them can be calculated.

speed of 70min-1. The solid line represents analytical values, and

New ProductThis has made it possible to analyze the fluidity of resin not only ineach dot an experimental value. An experimental value is an average

the axis direction but also in the circumference direction of theover time while an analytical value is a mean value of pressure

screw across the screw element.

distribution in the circumference direction of the screw. As a resultof the experiment, it was revealed the analytical values were in good
agreement with the experimental values.

SeriesPatent News

Fig. 3 2.5D FEM Hele-Shaw flow model element for the Twin-Screw Extruder

Prepared CritiqueFig. 5Comparison of the experimental values and the analytical values

Application of the Laser Light-Section
Method for Fill Ratio Measurement

3

Experiment and Verification

3.2.

3.1.

Experiment and Verification Based on
Resin Pressure Distribution

Next, the results obtained through the analytical approach
proposed herein were validated in another experiment in which a fill

In the experiment, the results obtained through the analyticalratio was measured. Note a fill ratio is one of the status indicators ofapproach proposed herein were validated through the measurement

the fluidity of resin in the Twin-Screw Extruder. It indicates how

21

Shibaura Machine Engineering Review

Table 1

much resin resides relative to the feed volume of the screw. The laser

Operating conditions
Introductory Note

light-section method was applied to measure a fill ratio. The laser
light-section method is a method of measuring the profile of an
object by applying a laser beam as a line around it. In the experiment,a line laser was used to apply a laser beam onto the open port of theTwin Screw Extruder, and then the cross-sectional profiles of theSpecial Article

screw and the resin were recorded using a high-speed camera. After
that, the amount of resin resided relative to the conveyable volumeof the screw was measured through the image analysis on therecorded data. Fig. 6 illustrates the profile of the twin screws and thesystem layout.

Technical Paper

shape on the screw surface from the one captured through image
processing. Fig. 8 is a graph representing how the screw is filled withresin based on the captured line shape. The black line represents thefigure shows resin resides in the area between the black line and theFig. 6

System overview

The experimental material used was homo polypropylene(F-704NP), which was the same as the measurement of resin pressure

red line on the right side. Next, Fig. 9 shows the graphs to compare

Technical Reportcross-sectional profile of the screw, and the red line that of resin. This

the experimental values with the analytical values based on the
results.
New Productdistribution. Also, TEM-26SX (L/D = 40) was used. Fig. 7 shows thescrew configuration and the point of measurement of a fill ratio.

SeriesFig. 7

Device configuration

Table 1 shows the operating conditions in the experiment. Screw
Patent News

speed was changed from 37 to 88 min-1, and throughput from 1.0 to
3.0 kg/h. It is investigated the independence on a screw speed at a
throughput of 1.0 kg/h, and on a throughput at a screw speed of 88
min-1 for fill ratio. This article will just present the results of theFig. 8

Profiles of the resin and the screw surface(88 min-1, 1 kg/h)

The analytical approach proposed herein made it possible tooutput a detailed profile of resin on the flow channel of the screw.

The shape of the laser beam applied onto the screw and the surface

Then, the amount of resin filling the screw can be identified asof the resin was captured from a video file using MATLAB® Image

shown by the red lines in Fig. 9. The results of the experiment are

Processing Toolbox® (MathWorks®) and Signal Processing Toolbox®

almost identical to those of analysis. This means as throughput(MathWorks®). The volume of resin was calculated by taking the line

increases at the same screw speed, the fill ratio similarly increases.

Shibaura Machine Engineering Review

22

Prepared Critiqueindependence on a throughput for fill ratio.

Introductory Note5

SummaryThis study has revealed the Hele-Shaw flow model-based 2.5D
FEM analysis enables us to analyze the state of the flow of the resin
in detail in the axis direction and the circumference direction of thescrew inside the Twin-Screw Extruder by solving the equation of theSpecial Article

viscous fluid between the two adjacent cylindrical columns. In
addition, this result has proved it is possible to design a device
configuration from the perspective of a molding process in response
to increasing demand for more advanced product developmentusing the Twin-Screw Extruder. Additional experiments andverification were conducted on devolatilization and fiber length

Technical Paper

attrition, which actually take place in product development, anddemonstrated the analytical values were in good agreement withthe experimental values, though the details are omitted due to thepage restriction.

Technical Report

Acknowledgements
I would like to express sincere gratitude to Professor Kentaro TAKI,
Kanazawa University, College of Science and Engineering, School of
Mechanical Engineering for his kind help and advice.
In addition, I wish to extend special thanks to Mr. Shinichiro TANIFUJI

New Productand Mr. Daisuke YORIFUJI, HASL Co., Ltd. for offering the analyticalsoftware, improving its performance, and giving me kind advice andopinions.

Fig. 9 Comparison of the experimental values and the analytical values(Fill ratio in the profile of the screw)

Reference
Masatoshi OHARA, Study on an Effect of a Fill Ratio in a Twin-Screw

SeriesExtruder on Devolatilization and a Rupture of Glass Fibers Based on a4

Conclusion

The laser light-section method, in which a laser beam is applied asa line for image processing, was introduced to measure the profile ofPatent News

resin in the Twin-Screw Extruder online. It was found through theexperiment as throughput increased, fill ratio also increased.
The resin pressure distribution and the fill ratio derived from 2.5D
FEM numerical analysis based on the Hele-Shaw flow model werePrepared Critiquealmost identical to the data obtained through the experiment. The
analytical approach proposed herein has enabled us to accurately
determine the flow of resin in the Twin-Screw Extruder and predictthe physical properties of a product based on distribution ofresidence time, thermal history, strain history, and others.

23

Shibaura Machine Engineering Review

Newly Developed Numerical Analysis Method, Doctoral Dissertation
at Kanazawa University, 2021

Technical Paper

It is generally ideal that casting pressure, which is one of the injection settings of the die castingmachine, is started in the shortest time after molten metal is filled in a product cavity. However, toeffectively transmit casting pressure to the product cavity, it is affected not only by the injection

Introductory Note

Investigation of Pressure Propagation Characteristics in Die Casting Method

settings but also by the molten metal and the mold temperature. Moreover, it was not enough tostudy, we attempted to clarify how casting pressure, together with other factors, affects productResearch & Development Center
Research & Development Department

quality.

Hiroki AMEZAWA

Introduction

speed range, and molten metal temperature, so it is not sufficient toquantitatively judge how much casting pressure alone affects

In the automobile industry, efforts to reduce CO2 emissions on a life

product quality. Therefore, we investigated how casting pressure

cycle basis, including not only when driving a car but also from

affects product quality by orthogonal array experiments based on

production to disposal, are accelerating in order to curb global

quality engineering.
Technical Reportwarming. Therefore, production machines also need more technology
which contributes to CO2 reduction.

Methods

development of energy-saving technology by downsizing the

3.1

Orthogonal Array Experiment Conditions

machine is notable. For downsizing the machine, it is necessary to

Based on quality engineering, we selected factors which may

have a low-pressure technology which enables casting with theaffect product quality and evaluated the effects of each factor andminimum casting pressure to achieve the required product quality.

interaction. We conducted experiments under 8 factors and 2 levels

However, since the setting standard of casting pressure is not clear, it

according to the orthogonal array in Table 1. The factors to be taken

is often judged from the experience of die casting and product quality,

up in the interaction of casting pressure were high-speed injection

which makes it difficult to easily reduce casting pressure. Therefore, tospeed, intensify time, molten metal temperature, temperature ofdevelop technology for lowering the pressure, it is first necessary tomold temperature controller, vacuum setting, and pouring time.
Table 1

Orthogonal array

Seriesclarify how the casting pressure propagates to the product. In this

New Product3

Considering the technology in die casting machines, theTechnical Paper

1

Special Article

confirm the effectiveness of the casting pressure based on these factors in actual casting. In thisstudy, we report the role of casting pressure on product quality andthe relationship between casting pressure and other factors for the
purpose of clarifying the propagation of casting pressure.

Patent News

2

About the Role of Casting Pressure
and Product Quality

In die casting, gas porosity formed by gas entrained during fillingof molten metal, and shrinkage porosity formed by volume

generated inside products. Generally, casting pressure improvesinternal quality of products by shrinking porosity.

Fig. 1 shows the half-pipe shaped test piece and various sensors /On the other hand, product quality depends not only on casting

quality evaluation measurement points. Other conditions are shownpressure but also on various factors such as intensify time, high-in Table 2. Table 3 shows the specifications of the die casting machine

Shibaura Machine Engineering Review

24

Prepared Critiqueshrinkage due to a decrease in temperature of the molten metal, are(DC350R-EH) used. ADC12 was used for the experiments.
Introductory Note
Special Article

Fig. 1 Test piece shape and various measurement points

Table 3

Table 2 Mold conditions

Specifications of the machine
Fig. 3

Measurement waveform example and measurement definition

From the measurement waveform, the start of rising pressure inTechnical Paper

the mold results from resistance when the molten metal fills the
product cavity and the molten metal passes to the gas vent side,which almost coincides with the detection timing of the molten

Technical Report

In order to effectively transmit the casting pressure produced bymetal temperature. In addition, the peak pressure transmitted to thethe injection piston of the machine to the product cavity filled withproduct cavity is about 75% lower than the casting pressure. This

the molten metal, it is important to pressurize the molten metal

results from molten metal solidification progressing due tobefore it solidifies. Therefore, an optical fiber type radiation

temperature decrease with pressure propagation deterioration.

New Productthermometer temperature sensor was installed in the product cavity

Five samples were taken under each condition, and the quality

to directly measure the temperature of the molten metal. Since it isevaluation was based on the ratio of porosity at the CT scannecessary to measure the temperature of the molten metal in themeasurement points in Fig. 1. From these results, the influence of

product cavity in a non-contact manner, we created the pin shown

each factor on product quality was evaluated.

in Fig. 2 with glass placed at the tip of the pin to protect the sensor
from the molten metal. In addition, pressure sensors were installed

3.2

to measure the change in pressure due to the temperature change

Fig. 4 shows the ratio of porosity by the CT scanner under eachin the solidification process.

Experimental Results

condition. In general, gas vent with a vacuum device is effective in
reducing the gas porosity, and the results of this experiment show

Seriesthe porosity ratio has decreased by 60% on average. On the other
hand, conditions 3, 10 and 12 are not good because there is novacuum. Therefore, it was determined the porosity ratio is greatly
affected by the amount of gas. However, since the porosity ratio islower even under conditions 15 and 16 without vacuum than under

Patent News

Fig. 2Temperature sensor

condition 2 with the vacuum, it is apparent the results are not always

On the other hand, the measurement data of the injection
position, the injection speed, and the mechanical pressure were
measured at the same time so the molten metal temperature andPrepared Critiquethe pressure inside the mold could be compared with the injection
state. Fig. 3 shows an example of the measurement waveform andthe measurement definition. However, the pressure inside the moldin 3.2 experimental results deals only with the gas vent side facing
the measurement point of the molten metal temperature.

25

Shibaura Machine Engineering Review

Fig. 4

Porosity ratio

good if a vacuum device is used.
Introductory NoteFig. 5 shows the results of classifying the effects of peak pressurein the mold on the porosity ratio by vacuum setting. With vacuum,
the porosity ratio tends to decrease as the peak pressure in the moldincreases, but there is no correlation without vacuum. In thisexperiment, it is apparent the porosity ratio was more influenced by

Fig. 7

Effect of intensify time on porosity ratio

time. Fig. 7 shows the effect of the intensify time on the porosity

Special Article

the gas than the peak pressure in the mold.

ratio. When the intensify time is short, the peak pressure can beincreased even if the casting pressure is low, and the porosity ratio isis possible by shortening the intensify time.
In addition to the intensify time, high speed is the main effect in theFig. 5 Effect of peak pressure on porosity ratio

Technical Paper

reduced. Therefore, it is clear casting with a reduced casting pressure

graph of factorial effects, so time is an important factor for increasing

the porosity ratio, the graph of factorial effects of Fig. 6 is shown. The

efficiency on elapsed time (filling time + intensify time). The pressure

casting pressure is not recognized as the main effect, but high-transmission efficiency indicates the ratio of the peak pressure to the

speed, intensify time, vacuum setting, and pouring time are

casting pressure. From Fig. 8, the pressure transmission efficiency

recognized. In particular, the effect of high-speed / vacuum setting

increases as the time becomes shorter. This is because the shorter theis great. The factors which increase the interaction with casting

elapsed time, the higher the molten metal temperature is maintainedpressure are intensify time, temperature of mold temperatureand the higher the peak pressure, as shown in Fig. 9.

New Productthe peak pressure. Fig. 8 shows the effect of pressure transmission
Technical Report

Next, in order to confirm which factors other than vacuum affects

controller, and pouring time. From these results, it is apparent
casting pressure alone does not significantly affect the porosity
ratio, but interaction with the other above factors are affective.
From here, the evaluation was performed only with vacuum toreduce the influence of gas. From the graph of factorial effects, theSeriesfactor which increased the main effect / interaction is the intensify

Fig. 8

Effect of pressure transfer
efficiency on elapsed time

Fig. 9Effect of in-mold peaktemperature on elapsed timepressure transfer efficiency. Fig. 10 shows efficiency increases as the

Patent News

Fig. 10 shows the relationship between peak temperature andpeak temperature rises. From the above, it was found it is importantto keep the molten metal temperature high by shortening theis the actual efficiency of the casting pressure.
However, in Fig. 10, condition 13 has a faster injection speed thancondition 1, that is, the pressure transfer efficiency is about 10%
Fig. 6Graph of factorial effects

lower despite the shorter time. Since the vacuum, intensify time,

Shibaura Machine Engineering Review

26

Prepared Critiqueelapsed time to increase the pressure transmission efficiency, whichpressure transmission efficiency. If the high-speed range is short,
Introductory Notethe pressure transmission efficiency tends to decrease. This isbecause the pressure transmission efficiency on the gate side was
reduced as shown in Fig. 13, and the gate was blocked early if thehigh-speed range was short.

Special Article

Fig. 10

Relationship between peak temperature andpressure transfer efficiency

and casting pressure settings are the same, other factors must havean effect.

Technical Paper

4

Discussion

Fig. 12

Effects of high-speed range
on pressure transmission
efficiency 1

Fig. 13

Effects of high-speed range
on pressure transmission
efficiency 2

Fig. 11 shows the representative injection waveforms of conditions

Technical Report

1 and 13. Condition 13 has a higher peak temperature than condition

In this study, we did not consider condition 1 in Fig. 10, which has

1 due to its high speed, but the peak pressure (gas vent side) is lower

a low peak temperature but a high pressure transfer efficiency. In

than condition 1. On the other hand, under condition 13, the pressure

the next survey, we would like to install a temperature sensor on theinside the mold (gate side) reacts at the same time as the fillinggate side and measure at the same time on both the gate / gas ventresistance suddenly rises, and the pressure inside the mold drops

side to acquire data which will lead to further consideration andearlier than under condition 1.

advance elucidation of pressure propagation.

New Product5

Conclusions

1) The casting pressure has a small effect on the internal quality ofthe product and is affected by the interaction between theintensify time, the molten metal temperature, and the pouring
time.

Series2) The peak pressure in the mold, which is the effective value of thecasting pressure, is increased by shortening the intensify time,
and the internal quality of the product is improved.
3) The pressure transmission efficiency, which is the actual efficiency
of casting pressure, increases as the peak temperature rises, but

Patent News

Fig. 11

Representative injection waveform of conditions 1 and 13

this is not always the case due to the influence of other factors.

In general, the narrower the gate, the higher the filling resistance.
Therefore, in condition 13 in which the high-speed range is short,

Reference

the molten metal was filled to the vicinity of the product gate at a1) Satoru AIDA, et al. : Papers of Japan Die Casting Conference (2018)

Prepared Critique

low speed, so the molten metal was easily solidified. As a result, thegate portion solidified and closed at an early stage in the pressure
increasing process, the pressure was not effectively transmitted to
the gas vent side, and the peak pressure (gas venting side) did not
rise. Fig. 12 shows the effect of different high-speed range on

27

Shibaura Machine Engineering Review

JD18-3

Technical Report

Molded parts using a polyolefin-based resin are often used in vehicle parts, and in future, the volume
used is expected to increase due to an expansion in their scope of applications. On the other hand,

Introductory Note

Development of Plasticization Device for Polyolefin-Based Resin
Molding with High Color Dispersion and High Plasticization Capacity

as the number of molded parts using this resin in any particular vehicle is large, compared to molded
and a guarantee of exterior quality, strength and other physical properties is required. As a result, aplasticization device which permits stable plasticization of the resin even at a high screw rotating
speed during high-cycle molding is required in injection molding machines. This paper reports on aplasticization device for polyolefin-based resins which was developed to meet this requirement.

Introduction

Molded parts using a polyolefin-based resin are mainly used for

Takahiro WATANABE

standard screw (hereinafter standard screw), and a color dispersion
element which can minimize the drop in plasticization capacity
while raising the color dispersion of the master batch.

Technical Paper

1

Metal & Plastics Industrial Machine Company
Metal & Plastics Industrial Machine Technology
Department

Special Article

parts using other resins, the cost demand is stringent, and thus both a reduction in production cost

exterior and interior fittings in vehicle parts, and these are produced
to meet weight reduction and diverse design needs. On the other(1) ESB screw for high plasticization capacity and uniform melting

reduced by changing the coloring method for molded parts fromto a standard screw (Fig. 1). The extended length is used to expand

colored pellets that emphasize quality over cost to adding a

the area of the compression zone, and by providing a long sub-flightmasterbatch to natural pellets, and we were able to shorten thedesign over the metering zone from the middle of the compression

charging time required for plasticization of the resin and achievezone, a sufficient quantity of heat was imparted in this area, ensuringhigh-cycle molding to increase the production quantity per unit time.

uniform melting of polyolefin-based resins having a large melting

However, shortening charging time is achieved at the expense of thelatent heat. Based on this, charging at a screw rotating speed higher

color dispersion condition of molded parts using a master batch. As athan a standard screw becomes possible, thereby achieving a highresult, plasticization defects of the resin easily occur due to an

plasticization capacity.

New Product

An ESB screw has an extended effective screw length comparedTechnical Report

hand, regarding our initiatives to reduce costs, material costs are

insufficient amount of heat received etc., which often leads to color
unevenness and other molding defects. In order to achieve both an
Seriesimprovement in the production quantity per unit time through highcycle molding and molded parts with no color unevenness byimproving the color dispersion of the master batch with a highdilution factor, we have been working on the development of aplasticization device for polyolefin-based resin molding.

Patent News

Fig. 1

Standard screw and ESB screw

A comparison of the plasticization capacity of polypropylene

The key quality issue in molding parts using a master batch is tobased on a standard screw and an ESB screw of diameter of Φ60 mm

ensure the resin is melted, dispersed, and distributed uniformlyand Φ115 mm is shown in Fig. 2. Compared to a standard screw, aneven at the highest screw rotating speed, and this is an important

ESB screw with a diameter of Φ60 mm has an increased plasticization

factor in eliminating color unevenness in molded parts. To resolve

capacity of 114% and one with a diameter of Φ115 mm has an

this issue, we developed an ESB screw which can achieve bothincreased plasticization capacity of 67%.

2

higher plasticization capacity and more even melting than our

Shibaura Machine Engineering Review

28

Prepared CritiqueIssues and Features of Plasticization
DeviceTest conditions

As fluctuations in the resin pressure occur due to changes in the

Introductory Note

• Resin : Japan Polypropylene Corporation

resin viscosity and contamination by unmelted resin during

Polypropylene JP5GA

charging, the results show the smaller the range of fluctuations, the• Screw rotating speed:Φ 60 mmmore uniform the charged resin is in a melted state.

Standard screw 220 min-1

In a standard screw, the range of fluctuation in the resin pressure

320 min-1

at a plasticization capacity of 415 kg/h reaches 3.0 MPa at maximum.

Φ 115 mm Standard screw 110 min-1However, in an ESB screw, the same range of fluctuation at a138 min-1

plasticization capacity of 693 kg/h is 2.5 MPa at maximum. Therefore,

ESB screw
Special Article

ESB screw• Soak ratioNote) 1:2

we confirmed the melting condition is more uniform while achieving• Back pressure: 3 MPa

a plasticization capacity which is 1.6 times higher or more compared• Charging stroke: 2.5D

to a standard screw.

Technical Paper

Note) Soak ratio is the ratio of the charging time per cycle andnon-charging time(2) Cross ring effect as a color dispersion element
In colored molding by master batch, when molding a masterbatch at a high dilution factor in order to reduce material costs, nonuniform dispersion of the master batch tends to easily appear ascolor unevenness on the molded part surface. This defect tends toTechnical Reporteasily occur at a low back pressure and high screw rotating speed toshorten the charging time.
To improve color dispersion, we can either attach a uni-melt ring
like that shown in Fig. 5 to the screw tip as in the past, or use a special
Fig. 2

Plasticization capacity of polypropylene by screw

nozzle known as a mixing nozzle which is equipped with a dispersion

New Productfunction inside the nozzle. However, as the uni-melt ring constricts
In order to verify the uniform melting of each screw, we measured

the flow path of the melted resin just before the screw tip, thisthe range of fluctuation in the resin pressure of polypropylene

results in a drop in plasticization capacity and increases charging

during purging in a standard screw and an ESB screw of diameter

time, thereby increasing the molding cycle. Although a mixing

Φ115 mm. (Fig. 3, Fig. 4)

nozzle is able to maintain the plasticization capacity, the amount of
resin which needs to be discarded when changing resin or color isSeriesmore than that of an open nozzle, increasing the working timerequired to change color, causing a pressure loss in the nozzle part,and decreasing the pressure which can be used in filling the mold,which all leads to a drop in productivity.
To resolve this issue, we reviewed the design of the uni-melt ring

Patent News

Fig. 3Resin pressure when purging of a Φ115mm standard screw

Prepared Critique

Uni-melt ring
Fig. 429

Resin pressure when purging of a Φ115mm ESB screw

Shibaura Machine Engineering Review

Fig. 5

Newly developed cross ring
Color dispersion element

and developed a cross ring to achieve a color dispersion on par with

Test condition•Screw diameter: Φ60 mm

capacity (Fig. 5).

•Screw rotating speed : ESB screw

In order to compare the effect a difference in back pressure has on

Introductory Notea mixing nozzle while minimizing the drop in the plasticization

320 min-1

Standard screw 220 min-1

color dispersion at the following specifications, data obtained
under the following test conditions is shown in Fig. 6.

Special Article•Specification 1 : ESB screw•Specification 2 : ESB screw + uni-melt ring•Specification 3 : ESB screw + cross ring
Test conditions•Screw diameter: Φ60 mm•Molded part: Document caseTechnical Paper•Molded part weight: 450 g•Resin: Japan Polypropylene Corporation
Polypropylene JP5GA
Master batch: 1wt% (beige)
Fig. 7•Molding cycle: 60 s

Comparison of color dispersion and plasticization capacity

The color dispersion rating in Fig. 7 is a score according to a color•Back pressure: 3 MPa, 7 MPa, 10 MPa, 15 MPa

dispersion evaluation method which we developed, with a score of
8.0 or higher indicating good color dispersion. The ESB screw

Technical Report•Screw rotating speed: 320 min-1(Specification 1) has a high plasticization capacity compared to otherspecifications at all back pressures, but the color dispersion is poor

ESB screw + uni-melt ring (Specification 2) and ESB screw + cross ring(Specification 3) have good color dispersion, and a plasticization

New Producteven at a back pressure of 15 MPa. At a back pressure of 10 MPa, thecapacity of 247 kg/h and 273 kg/h respectively, while that of thecross ring (Specification 3) is 10.5% higher than the uni-melt ring(Specification 2). Although the standard screw (Specification 4) has
Comparison of color dispersion

good color dispersion at a back pressure of 7 MPa, the plasticization

Fig. 6 shows the status of color dispersion in the molded part forcapacity is 126 kg/h, so compared to the standard screw, the ESB

each specification, indicating color dispersion is better when thescrew + cross ring (Specification 3) has a plasticization capacity

color unevenness is smaller. Although color dispersion improves thewhich is 116.7% higher.
Based on this result, a case in which the plasticization capacity for

was observed even at a back pressure of 15 MPa in the ESB screw

each specification was replaced by the charging time is shown in(Specification 1). On the other hand, the color dispersion is about

Fig. 8.

Patent News

higher the back pressure is at all specifications, poor color dispersion

SeriesFig. 6the same at a back pressure of 10 MPa or higher for both the ESB
screw + uni-melt ring (Specification 2) and ESB screw + cross ring

Next, based on the data obtained with Fig. 6, a numerical rating•Screw diameter: Φ60 mm•Screw rotating speed :(vertical axis) of color dispersion and plasticization capacity (horizontal

ESB screw

320 min-1axis) are shown in Fig. 7 for each back pressure setting. The figure for aStandard screw

215 min-1

standard screw (Specification 4) is also indicated for reference purposes.

Prepared Critique(Specification 3). (inside red box of Fig. 6)

Test condition•Shot mass

450 g

Shibaura Machine Engineering Review

30•Molding cycle 60 s
Introductory Note

•Back pressure

achieve molding with good color dispersion and reduced material

ESB screw

10 MPacosts even when the content ratio of the master batch is diluted

Standard screw

7 MPafrom 2 to 3wt% to 1wt% with an open nozzle specification.

3

Summary

Special Article

In this paper, we reported on the development of a plasticization
device with a high plasticization capacity and high color dispersion
for molding polyolefin-based resins which can help contribute to an
improvement in productivity in the molding site. Besides being
used in the master batch for coloring purposes, a dispersion element
is also an important technique used in the molding of master batch

Technical Paper

addition for quality improvement, physical strengthening and otherFig. 8Charging time comparison

purposes. In addition to creating benefits by reducing the amount

When an ESB screw + cross ring (Specification 3) is fitted, theof waste caused by quality defects, reducing material costs,

charging time becomes 5.9 s, shortening by 7.0 s compared to theimproving productivity and so on, it also contributes to a reduction

12.9 s for the standard screw. By shortening the charging time, it isin the environmental load which has also been cited as a SDGs.

Technical Report

also possible to shorten the cycle time when cooling time is lessGoing forward, we will continue to contribute to society throughthan 12.9 s. In addition to increasing the production quantity per

the development of technology to resolve issues for a variety ofunit time by adopting a high-cycle, generally it is also possible toresins and molded parts.

New ProductUpon Receipt of a Request

SeriesPatent News
Prepared Critique
31

When I was a university student,

the worker kindly asked me questions in detail, including the

one day I went to a machine tool room

meaning of the dimensions on the drawing, the level of precisionin the university with a drawing to ask

required, the environment in which the part was to be used, andfor the manufacture of a part to bewhether another material could be used since the designatedused in an experiment. The machinematerial was difficult to process. I was not able to provide

tool room was dedicated to produc-

adequate information then because I did not yet understandResearch & Development Center
Research & Development Department

tion of equipment and parts for use inwhat information was needed to produce the part I desired. I also

Miyu OGAWA

experiments. When I stepped into therealized it is essential for the person receiving a request toroom, I found many machine tools,

carefully listen to the requester to obtain all necessary information

along with the smell and clank of metal, with which workers were

to fully understand what was really required. So, when we make a

devotedly working. When I asked one of the workers to make therequest, we should carefully consider what information is neededpart I needed, upon showing him the drawing he advised me myfrom the standpoint of the person receiving the request. On thedrawing was not adequate. Since the information on the drawing

other hand, when we receive a request, I hope we can try tocreated by me, who belonged not to the Mechanical Engineeringcorrectly understand the content of the request and respond in

Department but to the Information Department, was insufficient,

an appropriate way.

Shibaura Machine Engineering Review

Technical Report

Introductory Note

Optimization of Extrusion Process Engineering for the Invention ofHigh-Performance Materials
Plastics, featuring high moldability, high functionality, and light weight, arefinding wider application while the circumstances surrounding the plastics
industry are becoming more challenging, with focus on environmental
the usage of plastics. In connection with SDGs, this article is titled
Optimization of Extrusion Process Engineering for the Invention of HighPerformance Materials. It reports the manufacturing of plastics and our

Metal & Plastics Industrial Machine Company
Extrusion Machine Engineering Department

Metal & Plastics Industrial Machine Company
Extrusion Machine Engineering Department

optimization of process engineering for the effective utilization of biomass-

Shozo SUZUKI

Hiroshi MOMOCHISpecial Article

loads typified by microplastics in the ocean and efforts by society to reduce

derived materials from the perspective of reducing environmental loads.

Introduction

materials containing bioplastics or bioplastic compounds, identify
extensive applications, and promote mass production.
As described above, extrusion process engineering is involved ina rapidly increasing number of initiatives to reduce the usage ofthe manufacture of plastics and alternative materials and has aplastics, including material bans and charging for plastic shopping

direct effect on reduction of environment loads in many aspects.

bags and straws. Considering such circumstances, we expect society

The following sections will introduce specific examples of the efforts

to quickly evolve toward low-carbon and sound material-recycling

for process improvement utilizing our lineup of extruders and thein the near future, further reducing environmental loads.

optimization of extrusion process engineering for the invention of

Looking around the world, individual nations are working toward

high-performance materials.

plastics industry is also pushing forward with the effective use of

2

Ultra-Deep Channel Type
Twin Screw Extruder (TEM-DS/DSS)

natural resources, anti-pollution measures, 3R (Reduce, Reuse andShibaura Machine’s product lineup offers several models of twin

Recycle) based on resource recycling, development of alternative

screw extruders (TEM Series) with different screw profiles andmaterials, and automation and labor saving in manufacturing plants.

torques according to application purposes.
SeriesOn the other hand, plastics have excellent material properties

New Productachieving SDGs (Sustainable Development Goals), which wereadopted at the UN Summit in 2015. Consistent with this trend, theTechnical Report

Plastic pollution has been receiving global attention and there areTechnical Paper

1

allowing them to be flexibly used according to the application
purposes of products. Therefore, plastics are expected to play roles
in reducing CO2 emissions through weight saving and lowering
environmental loads.

Patent NewsIn addition, as measures against climate change and global
warming, the shift to electric vehicles (EVs) or hybrid electric vehicles(HEVs) continues to make low-carbon society a reality. EVs and HEVs
are equipped with lithium-ion batteries (LIB) as power sources, inFig. 1

Lineup of twin screw extruders (TEM)

Furthermore, bioplastics are gaining the spotlight as materials
which will likely contribute not only to reduction in the consumption

Among the models, the Ultra-Deep Channel Type “TEM-DS/DSS

of exhausted resources such as oil, but also the prevention of global

Series” has high torque and a D/d of 1.8. This makes it possible towarming. For this reason, endeavors are being made to; invent

keep a minimum flight top necessary to provide effective shear

Shibaura Machine Engineering Review

32

Prepared Critiquewhich battery separator films are made from plastics.

Introductory Note

performance, and consequently the space volume has increased byCompared to the Deep Channel Type with constant screw center

1.4 times compared to the conventional Deep Channel Type. The

distances, the Ultra-Deep Channel Type can offer a large space

Ultra-Deep Channel Type has the following advantages.

volume, thereby lowering fill ratio with the same throughput. Thismeans an increase in space with low fill ratio or free surface area of• Low-shear forces and mild kneading

ingredients. Therefore, the Ultra-Deep Channel Type is superior toSpecial Article

Fig. 2 shows a comparison between the Ultra-Deep Channel Typethe Deep Channel Type in both the thorough and continuousand the Deep Channel Type in a profile. In addition, Fig. 3 shows the

movement of ingredients with even kneading, and the surface

simulated resin temperature distribution of each profile. As shown

renewal effect per unit area under the same operating condition.

in Fig. 3, temperature locally rises near the flight top (yellow) in the

In addition, when a comparison is made in the process parameters

Deep Channel Type while such temperature rise is suppressed in theunder the same conditions, ingredients reside in the machine longer

Ultra-Deep Channel Type.

(See Fig. 4). Therefore, the Ultra-Deep Channel Type is more effective
than the Deep Channel Type in reactive processing, which involves aTechnical Paper

melting and kneading process through a chemical reaction. For thisreason, there are an increasing number of cases where conventional
batch production is replaced with continuous production using the
Ultra-Deep Channel Type twin screw extruder.

Technical Report
Fig. 2

Cross-sectional profiles

New ProductFig. 4Comparison in a residence time (Raw material : PP + talc 30%)

Combined with its superior surface renewal effect, the Ultra-Deep
Channel Type provides a larger exposure area than the Deep
Fig. 3
SeriesDifference in a resin temperature distribution
between the profiles•Discharge increase from high feed acceptance performance
When the conventional Deep Channel Type is used to process raw

Channel Type, which is important in a devolatilization process. This
gives the Ultra-Deep Channel Type superb capability to remove or
separate volatile components, and eventually it will contribute to
the invention of low VOC materials. Moreover, the Ultra-Deepmaterials with a low bulk specific gravity such as fluff, pulverizedmaterials, and powders, a suitable bore diameter must be selected
Patent News

based on a feed limit in the same process. On the other hand, if the
Ultra-Deep Channel Type, with a large space volume, is used, amodel with a smaller bore diameter can be selected due to its highfeed acceptance performance of raw materials. This will lead toPrepared Critiquereduction in energy consumption and an increase in both operability
and productivity.

•High distribution and compounding performance, prolonged
residence time, and devolatilization performance

33

Shibaura Machine Engineering Review

Fig. 5Comparison in devolatilization efficiency and hue (YI)

used as films for illuminated signboards or synthetic paper. Recently,

top. Therefore, it offers an advantage in both devolatilization andthere is growing demand for finely porous films because they findhue (YI). Fig. 5 shows the results of comparison and verification.

their ways into battery separator films in lithium-ion batteries (LIB).
EVs are expected to rapidly become widespread in the future, but

3

Recycling

their driving range cannot be improved without increasing theIntroductory Note

Channel Type can suppress local temperature rise near the flightcapacity of batteries. Also, battery separator films need to be madethinner, and productivity, film strength, and physical properties

be effectively used for the purpose of recycling pulverized PET

should be further improved. Therefore, endeavors are being madebottles and films. In particular, the most likely case is where wastage

to further upgrade the characteristics of raw materials and thedue to trim loss or stamping in the secondary processing, or

plasticizing process.
In addition, because of rapidly growing demand for batteries andproduction line for recycling without being pelletized in the process

price competition, the need for more battery separator filmof manufacturing plastic sheets or films.

manufacturing equipment, as well as increased extrusion speed andFurthermore, the effective use of the twin screw extruder inwidth, are growing to address increased production efficiency. It is

combination with vacuum equipment can prevent molecular massvital to establish production engineering to meet such market

reduction or polymer degradation due to hydrolysis without pre-needs.

Technical Paper

pulverized defective moldings, are directly returned to theSpecial Article

The large space volume in the Ultra-Deep Channel Type can also

drying raw materials. As a result of this advantage, along with low-

rapidly finding application in sheet or film manufacturing. In fact,

5

Application of the Ultra-Deep Channel
Type to Battery Separator Manufacturing

Extension and phase separation is an important process in battery

content of at least 70% by weight is used in actual sheet

separator film manufacturing. Besides this, an extrusion process

manufacturing. A-PET sheets, which are materials for food trays,

where raw materials are kneaded also significantly influences film

food containers and covers, are typical application examples.

quality.

Some of the sheets introduced above are commercialized as

It is very beneficial to use the Ultra-Deep Channel Type in therecycled trays. They consist of multiple layers. A recycled material is

extrusion of wet battery separator films, where base resin andused to form an intermediate layer, and virgin resin forms the surface

incompatible plasticizer (fluid paraffin) are compounded in large

layer in contact with food.

quantity. In particular, it will greatly help to minimize damage to the

In this process, hydrolysis develops so quickly at high temperaturebase resin, achieve high dispersion in phase separation, andeventually strengthen thinned films.

dewater it without exerting excessive shear energy in order to

The large space volume in the Ultra-Deep Channel Type increases

maintain quality. But these challenges can be solved by optimizing

the space not filled with resin and enhances ease of kneading as

the screw configuration of the twin screw extruder.

shown in Fig. 6. This makes it possible to produce the effect ofSeriesin PET resin it is important to efficiently melt resin and quickly

New Productthere is a case where materials with a pulverized raw materials

Technical Reporttemperature extrusion performance, the Ultra-Deep Channel Type is

distribution and evenly kneaded resin.

Finely Porous Film

In addition, as mentioned above, the Ultra-Deep Channel Typemakes it possible to suppress local temperature rise caused by shear.
Therefore, it can maintain higher viscosity and more effective

50μm size range. They are high-performance materials which cankneading at a lower shear speed compared to the Deep Channel

control the passage of fluids or particles by the hole diameters andType. As a result, it becomes possible to homogenize the raw

structures. Finely porous films are conventionally used as breathable

materials of a super-high molecular battery separator, whose

films, which are raw materials for disposable diapers, feminine

average number of molecules exceeds 1 million. Fig. 7 shows thehygiene products, and protective clothes. They are also alternatives

results of comparison in film strength between an ultra-highto paper because of their good light transmittance and texture andmolecular mass compound and an existing product.

Shibaura Machine Engineering Review

34

Prepared CritiqueFinely porous films have countless fine pores in the 0.01μm toPatent News

4

Low-temperature extrusion is a key to improving hue, so it isIntroductory Notenecessary to come up with an ingenious way of effectively kneading
at lower shear speed. (The next section will describe the example
application.)

7
Special Article

Fig. 6

Difference in kneading between Deep Channel Typeand Ultra-Deep Channel Type

Example Application of the UltraDeep Channel TypeShibaura Machine owns the core technology of extrusion dewatering
which was developed in the manufacture of ABS resin and thedewatering and drying of synthetic rubber. This technology can also be
applied to the extrusion of bioplastics, which have hydrophilicity. (SeeFig. 9 for Shibaura Machine’s approach to dewatering.)

Technical Paper

This section introduces the case where we succeeded in mass
production while maintaining the hue of biodegradable plastics
with water content of approximately 20%.
When a standard approach with a Deep Channel Type profile wasused for extrusion, vent-up or cut strand frequently arose from an

Technical Report

Fig.7

Comparison in film strength between an ultra-high molecular masscompound and an existing productexcessive amount of remaining moisture. When the approach ofcompression dewatering was adopted, dewatering performance
was improved, but hue was considerably worsened due to excessive

6

Bioplastics

New Product

Bioplastic is a generic name of biomass plastics which are madefrom recyclable organic materials such as plants, and biodegradable

shear after compression. Then the approach of vaporization was
adopted, where water was successfully removed in stages utilizing
latent heat of vaporization of moisture content. Finally, good results
were obtained.

plastics which are naturally decomposed by microorganisms.

These results were applied to the Ultra-Deep Channel Type. Due

Biodegradable plastics are expected to gain popularity but are lessto the suppression of local temperature rise, hue was significantly

productive and cost-effective in production compared to common

improved, but it did not lead to increased throughput due topetroleum-derived general-purpose plastics.

insufficient dewatering. One reason the expected result could not

SeriesIn addition, biodegradable plastics are inferior in moldability andbe obtained was the application of the Deep Channel Type device

thermal stability. Therefore, they are easily colored due to excessive
heat or shear. Fig. 8 shows the relationship between barrel temperatures and hues when extruding glucose biodegradable plastics.

Patent News
Prepared CritiqueFig. 835

Relationship between mold temperatures and hues

Shibaura Machine Engineering Review

Fig.9

Extrusion dewatering with a twin screw extruder

configuration. Based on these findings, the screw configuration was
Introductory Noteoptimized, and a thorough search was made for the best operating
conditions. Finally, throughput was successfully improved by 1.4
times compared to the Deep Channel Type.

8

Conclusion
Special Article

As the industrial structure changes and the economy matures, theneed for the type of extruders produced by Shibaura Machine is
becoming more diverse. It is therefore important to develop a
process of inventing high-performance materials with the purposeof not only increasing capacity and high quality, but also

Technical Paper

environmental conservation and the achievement of low-carbon
society. We consider it our responsibility as a manufacturer tocontinuously strive to contribute to the development of asustainable society through our business activities.

Technical Report
New Product
SeriesPatent News
Prepared Critique

Shibaura Machine Engineering Review

36Technical Report

Introductory Note

Development of High-Precision Machining Technology
Using the BTA Deep Hole Drilling Machine DBH
BTA is an abbreviation acronym for Boring & Trepanning Association,and it refers to deep hole cutting, which is one of the most important
processes in metalworking. BTA processing has the advantage of being

Special Article

able to drill clean and accurate deep holes (deep hole drilling) at highspeed. Since most hole machining is done at the beginning of themachining process and the hole machined at that time is used as thereference in the subsequent processes, lesser accuracy has been required
for the bend (out of position) and roundness of the machined hole.
However, in recent years, to integrate processes and improve machining

Machine Tools Company,
Machine Tools Engineering
Department

Machine Tools Company,
Machine Tools Manufacturing
Department

Kazuhiro SEKI

Ken ITO

Technical Paper

efficiency, the standard in the final process has been set as the outerdimension standard, and hole machining accuracy to that standard isoften required. This paper presents an overview of BTA deep hole drilling
and the technology used to achieve high-precision deep hole drilling
aimed at process integration.

Technical Report

1

Introduction

The global market for deep hole drilling machines is expected to2Outline of BTA Deep Hole Drilling
Machine2.1

What is BTA Processing?

New Product
Seriesgrow at an annual average growth rate of 5.8% from 2020 to 2027,

Deep hole drilling is a process in which the depth of the hole isexpanding to 126% over 2019 in 2027. Also, the global market for

generally 100 to 200 times the hole diameter. The BTA method,

deep hole drilling tools is expected to grow at an annual average

because of its superior structure in terms of chip evacuation, rigidity,

growth rate of 4.75% from 2020, with the growth drivers including:and productivity, has the advantage of high-speed and clean

the automotive industry, which is increasingly focusing on electric

drilling, which is why the BTA method is the first choice for deep holevehicle parts; industrial machinery, where high-precision operations

drilling. In the BTA method, cutting oil is pumped from the tank towill increasingly be required even for large-sized machines in

the oil pressure head (pressure head) in contact with the workpiece,

response to growing demand for automation; infrastructure; energy

passes through the ring-shaped space between the drilled hole andindustries; aerospace; and defense1)-2). If deep holes can be machined

the boring bar, reaches the cutting edge, and returns to the oil tankmore cleanly and accurately, it will help to integrate processes,with the chips through the boring bar (Fig. 1).

Patent News

improve machining efficiency, and reduce frictional resistance in the

Therefore, the chips do not contact the inner surface of the drilled

driving parts of automobiles, construction machinery, and industrial

hole, so they do not damage the inner surface of the hole, resulting

machinery, thereby contributing to improved fuel efficiency andin a very clean machined surface.

reduced energy consumption. In the case of power generationBoring headrelated components, improved deep hole drilling results in reduced

Workpiece

Oilpressure Oil pressure headgauge (pressure head)
Boring bar

losses, leading to more efficient power generation, which is closely
Prepared Critique

Chipcatcher

related to efforts to achieve the SDGs. In the following, we will
introduce the details and results of our efforts to improve theCutting oil
pump
Tank

accuracy of deep hole drilling using our product, the BTA deep hole

Magnetfilterdrilling machine DBH-1015C.
Fig. 137

Shibaura Machine Engineering Review)

Schematic diagram of a BTA deep hole drilling machine3

2.2

2.4

Types of BTA Processing

Main Specifications of the DBH-1015C
Introductory Note

There are three types of BTA processing methods: solid boring,
Table 1 Specifications

trepanning, and counter boring. Each of them has its own purpose
and characteristics (Fig. 2).
Solid boring

Trepanning

Counter boringCore
sectionA method of drilling that leaves
a core in the center of the hole,allowing large diameter holes
to be drilled even with low
horsepower.

Fig. 2A method of widening the hole,used when dimensional accuracyof inside diameter is required, orwhen the hole is being preparedfor honing.
)

Types of BTA processing3

Technical Paper

2.3

Workpiece

Workpiece

The most common method for
drilling deep holes in solid statematerial

Special Article

Workpiece

Types of BTA processing machines

BTA processing often uses structural steel, stainless steel, prehardened steel, bearing steel (bare steel), tool steel (such as carbon,
alloy, and high-speed tool steel), corrosion and heat resistant alloys,
titanium, aluminum, copper, resin, among others, as work materials.

Technical Report

In BTA processing, it is possible to process not only round bars but
also square bars and block shapes. However, since the specificationsof the machine and the machining method differ depending on the
shape of the work material, general specifications are shown in Fig. 3.
Workpiece: rotation+Tool: ﬁxed

Based on the recent market requirements, we conducted various
verifications with the goal of achieving the machining accuracy
shown in Table 2 for five consecutive holes by solid boring. As
Hole bending: Minimum

mentioned above, deep hole drilling is generally the first process,Seriesand the required accuracy is often only surface roughness andstraightness. This is because the deep hole is used as the standard
Hole bending: Large

Types of BTA processing machines (Refer to the website of KAWAHARA.)4)

for the next and subsequent processes. For this reason, to emphasize
high-efficiency machining with high feed rate, the standard for deephole drilling accuracy is generally considered to be a diameter

Patent News

Fig. 3

Target Machining Accuracy

Hole bending: Small

Workpiece: ﬁxed+Tool: rotation
Can be used for any material shape;
can be used even for multi-hole
drilling.
It has a moving axis on either the
workpiece side or the tool side.
The hole bending is large.

3.1

Table 2 Target machining accuracy

Workpiece: rotation+Tool: rotation
Used for center hole drilling of roundbars or square bars (chuck jaw
forming required).
It is generally called a "relativerotation type" and features a smallerhole bending than other machining
centers.

High-Precision Deep Hole Drilling
Test

New Product

Used for center hole drilling of roundbars or square bars (chuck jaw
forming required).
* The DBH applies to this type. (Fig.
4)

3

tolerance of IT10 and a coaxiality of 1mm/1000mm.

Prepared CritiqueFig. 4 BTA deep hole drilling machine DBH-1015C

Shibaura Machine Engineering Review

38

3.2

Results of Normal Processing Test

Introductory Note

In order to check the current machining accuracy, we conducted
a machining test under the cutting conditions shown in Table 3. The
machining results are shown in Table 4. (Tool used: Throw-away typewith rear guide)

dynamic rigidity.
③As in ① above, the effect on coaxiality is small, but attention
should be paid to the effect on diameter tolerance.
④We compared the hardness between the workpiece and SCM440
raw material, but no significant difference was found. However,Table 3Special Article

Peripheral
Peripheral
speed
speed
73 m/min
73 m/minthe coaxiality tends to be better when the hardness is higher andCutting conditions

Feed rate
Feed rate
0.04 mm/rev
0.04 mm/rev

Cutting oil
Cuttingamountoil
amount55 L/min
55 L/minthe microstructure is less uneven.
⑤The faster the feed rate, the worse the coaxiality tends to be.
⑥No effect of the flow rate, pressure, and temperature of the cutting
fluid on coaxiality was observed. It should be noted as the cutting

Table 4

Results of normal processing test

fluid flow rate was increased, deterioration of surface accuracy

Machining accuracy [mm]Machining accuracy [mm]was observed due to micro-vibration of the tool within theTechnical Paper

Coaxiality
Coaxiality

Roundness
Roundness

1
1

φ0.070φ0.070

0.014
0.014

Diameter
Diametervariation
variation
φ0.008
φ0.0082
2

φ0.095
φ0.095

0.015
0.015

φ0.005
φ0.0053.4

3
3

φ0.020φ0.020

0.018
0.018

φ0.007
φ0.007

As stated in Section 3.3, we could not find any item which had aworkpiece.

Verification of Tools

significant relationship to machining accuracy, so we verified theTechnical Report

The results show one out of three consecutive machinings arewithin the target accuracy. However, it is clearly difficult to continuously

tool-related factors. For tools, we verified the shape and thedimensional adjustment of the guide pad (Fig. 5).

meet the target accuracy with the current machining method.
Bar tube

3.3

Verification of Machine-Related Factors

Tool body

New ProductBased on the results shown in Section 3.2, we investigated theTipfactors which affect the coaxiality of deep hole drilling.
①Poor alignment of spindle table etc. (static accuracy)②Insufficient rigidity of the machine body (static and dynamic)③Poor centering of workpiece④Uneven hardness of the workpiece (metallurgical structure,

Fig. 4

BTA deep hole drilling machine DBH-1015C

Seriesuneven wall thickness in the lower hole)⑤Cutting speed and feed rate

Rear guide
Guide pad

⑥Supply flow rate, pressure, and temperature of the cutting fluid⑦Shape and material of the tool (tip/guide pad)Fig. 5 Name of each part of the tool

We conducted verification through machining for each item, but
Patent News

improvements and changes in items ① through ⑥ did not achieve

3.4.1 Verification with Different Tool Structures

the target accuracy. The verification results for each item are as follows.

Three types of tools were used to verify the change in machining
accuracy under the same machining conditions as those in Table 3.

①In the case of the workpiece rotation type, the centering effectPrepared Critiquewhere the drilling tool moves closer to the workpiece rotation axis

②Throw-away type tool without rear guide

will be produced, so the effect of the alignment of the boring table③Brazing tool without rear guideor bar support is small. However, the alignment of the spindle* ① and ② are tools of the same manufacturer.

(workpiece) and guide bushing affects the diameter tolerance.

The results of machining with each tool are shown in Table 5.

②The DBH-1015C has sufficient capacity in terms of both static and39①Throw-away type tool with rear guideShibaura Machine Engineering Review

Table 5Tool verification results

Table 6 Tool adjustment verification results

Coaxiality

Diametervariation①

φ0.015

φ0.020φ0.010②

φ0.038

φ0.012

φ0.042③

φ0.155

φ0.017

Coaxiality

Diametervariation①

φ0.205

φ0.015②

φ0.580③

φ0.350Introductory Note

Machining accuracy [mm]Machining accuracy [mm]Tool

It was confirmed the larger the clearance amount between thethe tool, even under the same cutting condition. As shown in Fig. 6,

tool diameter and the rear guide diameter relative to the guide bushwhen the machining results of ① and ② were compared, there wasinner diameter, the worse the coaxiality tended to be. It was alsoa difference in straightness (hole bending) depending on theconfirmed an excessively small clearance amount, like the condition

presence or absence of the rear guide, indicating the rear guide has①, would lead to poor roundness.
Technical Paper

an effect on straightness.
Straightness of machined hole

Straightness [µm]Tool ② (large hole bend)

4

Special Article

It was confirmed the machining accuracy varied depending on

Continuous Processing

Based on the verification results, we optimally adjusted theclearance amount of the tool diameter and the rear guide diameterto the guide bush inner diameter of the tool with rear guide, andthen conducted a continuous machining test. We used the samemachining conditions as those in Table 3. By appropriately managing

Technical Report

Tool ① (small hole bend)

the clearance amount, the target accuracy was successively achieved.
Deep hole length [mm]Difference in straightness depending on the presence or absence of arear guide

Table 7

New ProductFig. 6The machining results are shown in Table 7.
Continuous machining results

Machining accuracy [mm]3.4.2 Tool Adjustment

Roundness

Diametervariation

1

φ0.0280.006

φ0.0092

φ0.0120.005

φ0.0073

φ0.0160.006

φ0.006

the guide bush inner diameter within the tolerance range and4

φ0.0200.006

φ0.006

verified the effect on the coaxiality. The conditions used for5

φ0.0430.004

φ0.007

In general, the recommended tolerances for the inner diameter ofthe guide bush are G6 tolerance for the machined hole diameterand h8 tolerance for the tool diameter. Based on this, we adjusted
the clearance of the tool diameter and the rear guide diameter toSeriesCoaxiality

verification were as follows.
①Near the lower limit of the clearance tolerance range (small②Near the middle of the clearance tolerance range③Near the upper limit of the clearance tolerance range (large

5

Consideration

From the above verification and results, it was confirmed in deep

Patent News

clearance)hole drilling the dimensional control of tool diameter, guide bush
inner diameter, and rear guide outer diameter affects the coaxiality

The machining results are shown in Table 6

and roundness of deep holes (red text in Fig. 7).

Shibaura Machine Engineering Review

Prepared Critiqueclearance)40

Guide bush

Guide bush
inner diameter

Rear guidediameter

Rear guideTooldiameterIntroductory Note

Guide padTip(intermediate edge)

Special Article

Workpiece(rotation)
Tip (outer edge)

Pressure head
(fixed)Tip (center edge)
Fig. 7

Details of machining section

In general, the management of tools and the operation of guidebushings are under the control of the customer, and the machining
Technical Paper

accuracy is also under the control of the customer. In the future, wewill be able to offer our know-how to customers who wish to use
BTA deep hole drilling machines for high-precision machining to
improve their productivity, using this verification as an example.
Moreover, to such customers, we would like to make a proposal not

Technical Report

only for machining tools but also for methods of utilizing deep hole
drilling tools and optimal tools, through partnerships with tool
manufacturers. If these proposals lead to the formalization ofmachining conditions and the improvement of the quality andperformance of deep hole drilling tools and their long life, we can

New Productexpect the optimization of the production process through the
improvement of machining quality and the reduction of industrial
waste such as defective products and consumables, which will havethe effect of reducing the environmental load.

Series6

Conclusion

In this report, we have examined the machining accuracy of deephole drilling, which has not been required so far. We will continue toexamine different materials, different types of tools, and different
machining methods such as counter boring and trepanning.

Patent News

References
1) Reportocean.com, "Deep Hole Drilling Machine Market Research
Report"Prepared Critique2) ANCA, "NewsLetter", January 2020.
3) Excerpted from the website of Japan BTA Co., Ltd. http://www.
fukaanaake.com/btaex.html（Ref. on 2021-11-18）
4) Excerpted from the website of KAWAHARA https://www.kawaharamachine.com/product/bta_index.html（Ref. on 2021-11-18）

41

Shibaura Machine Engineering Review

Technical Report

With the challenge of decarbonizing mobility being set forth as a green growth strategy inconjunction with attaining carbon neutrality by 2050, there are particularly high expectations for

Introductory Note

Ultra-Precision Machining Technology for Contributing to Higher
Power Density of Fuel Cell (FC) Stacks

fuel cell vehicles. Fuel cell stacks, which act as the power supply unit, are being rapidly developedwith higher power densities for practical use, and one reason for these dramatic technologicalplates ( separators ), of which several hundred are mounted in the power supply unit. This paper
will present an application example where ultra-precision machining technology was developedfor enabling ultra-precision machining of this micro-bipolar plate shape.

Kunitaka KURIYAMATechnical Paper

1

Machine Tools Company
Machine Tools Engineering
Department

Special Article

innovations is the high precision of the flow channels of the thin metal sheets called bipolar

Introduction

At the end of 2020, the Japanese government declared its policy
goal of achieving a carbon-neutral, decarbonized society by 2050, in
which the amount of carbon dioxide and other greenhouse gases

Technical Reportemitted and absorbed will be net zero. According to 2018 results,
about 20% of the country's 1.1 billion tons of carbon dioxide
emissions came from automobiles,1) and so major changes areneeded to adapt to a decarbonized society in the future. In response,
recent years have seen the rapid development of technologies in

FCVs are fueled by hydrogen and emit only water, and since they are
not fueled by fossil fuels and hydrogen can be generated indefinitely,
there are high expectations for them as the ultimate in clean
mobility for solving many environmental problems.

2)

Fig. 1

New Productfields such as electric vehicles (EVs) and fuel cell vehicles (FCVs).
Unit cell structure of a fuel cell stack5)

Higher performance of elements, such as the MEA and bipolar
plate, is a factor in the improved output density, but the bipolarhydrogen and air flowing on the front and back surfaces, (2) Finehydrogen and the oxygen in the air. A fuel cell consists of aand complex channel shapes to increase the contact area withmembrane electrode assembly (MEA) with electrocatalysts coatedhydrogen and air, and (3) Thin cells to increase the overall unit

on both sides of a polymer electrolyte membrane sandwicheddensity. However, in the conventional press, the thickness of the

between thin plates called bipolar plates, which are composed ofplate is not uniform due to insufficient machining accuracy of theseparate air and hydrogen flow channels. Fig. 1 shows an overview

mold, resulting in extremely thin parts. This can lead to holes in theof the set of structures called a cell. Hundreds of these cells areplate and the mixing of hydrogen and air. Therefore, the bipolar

stacked on top of each other to form the actual fuel cell stack unit.3)

plate requires a high-precision mold which can press the fine

The initial fuel cell stack developed in 2008 had a maximum

channel shape and plate thickness uniformly. This paper presents

output/volume of 1.4 kW/L (maximum output 90 kW/volume 64 L

examples of using an ultra-precision channel machining and(108 kg)), but the latest model has a maximum output/volume of 3.1

compensation method which was developed to improve thekW/L (maximum output 114 kW/volume 37 L (56 kg)), which is a 2.2-

performance of fuel cell stacks.

fold increase in volumetric output density and demonstrates the
rapid pace of miniaturization and performance improvements.4)

Shibaura Machine Engineering Review

42

Prepared Critiquegenerates electricity through an electrochemical reaction between

Patent News

plate must have three main features: (1) Complete separation ofSeries

The fuel cell used in FCVs is actually a small generator which

Introductory Note2

Ultra-Precision Machining Center
UVM

even most machining centers which claim to be high-precision useball bearings. While it is true that for high-precision applications, theSpecial Article

This paper examines the use of ultra-precision machining center

bearings are designed to be ultra-lightly pressurized, the rolling

UVM to achieve high precision in fuel cell bipolar plates. The UVM

elements of the bearing are in constant contact with the inner andseries is an ultra-precision machining center which incorporates theouter rings, and so vibration, heat generation and wear are inevitable

nanometer-order elemental technology6) developed for the ULG

when the bearing rotates. Compared to aerostatic bearings, ballseries, which is used in the field of optical lenses, into the realm of

bearing spindles have the following undesirable characteristics: (1)general-purpose machining. Fig. 2 shows the four models in theInferior rotational accuracy, (2) Heat generation during high-speed

UVM series lineup. The UVM-450C series standard model has a tablerotation, and (3) Inevitable deterioration over time.

Technical Paper
Technical Reportsize of 450 mm x 450 mm. To handle large workpieces, the UVM-

The aerostatic bearings used in the UVM series have a structure

700C's table work surface size has been increased to 700 mm x 700

where compressed air is supplied between the rotating shaft andmm, and the maximum loading weight has been increased to 400

housing to lift the spindle out of the bearing and hold it in place by

kg. The UVM-450D is equipped with a thermostatic system foraerostatic pressure. The air layer smooths out the accuracy error

strengthening the structure against environmental fluctuations andcomponents, making it possible to rotate smoothly, exceeding thean enhanced internal structure for vibration control and high-machining accuracy of each component adversely affecting the

precision positioning. The UVM-700E (5AD) is a 5-axis model whichrotational accuracy, such as the roundness and roughness of theprovides a high degree of freedom for large workpieces such as

rotating shaft and bearings, and reducing the effect of vibrations.

automobile headlights. All UVM series models are equipped with

Fig. 3 shows a comparison of the actual rotational accuracy

Shibaura Machine's aerostatic bearing spindle featuring a maximum

measured by a displacement sensor. The ball bearing spindle in the

speed of 60,000 min , and linear motor control with a minimum

figure on the left shows abnormal vibration errors due to the rolling

setting unit of 10 nm is used for all linear axes.

elements' turning motion as they rotate, while the aerostatic bearing-1

in the figure on the right shows no abnormal vibration errors and
New Productrotates with a smooth path.

SeriesBall bearing spindle

Aerostatic bearing spindle

Fig. 3 Comparison of rotational accuracy

Patent News

3.2
Fig. 2

UVM series lineup

Linear Motor Drive Control

All linear axis drives of the UVM series are equipped with coredlinear motors. The high-rigidity guiding mechanism has a structure

Prepared Critique3

Component Technologies

which minimizes the degradation of motion accuracy due to

3.1

Aerostatic Bearing Spindle

motors, and has the advantage of allowing the setting of highmagnetic attractive force, which is a concern with cored linear

Shibaura Machine has been developing aerostatic bearing

position loop gain and a control resolution of 0.5nm scale feedback.

spindles for their high-precision machine tools since the 1970’s.

As a result, the performance of the feed system has been improved

However, general machining centers use ball bearing spindles, andto a level where steps of 10 nm can be accurately controlled.

43

Shibaura Machine Engineering Review

measured at the same actual machining point as the tool tip. The

correction machining. Since the sensor structure makes this error

waveform shows positioning error at the cutting edge was reduced,

unavoidable, we studied replacement of the sensor with a method

and accurate and smooth reversing motion characteristics werecapable of measuring the tool contour more accurately and foundobtained with high response, which improves the machined surface

the imaging method to be the most suitable. However, the imaging

quality and minimizes manual finishing such as polishing andmethod tends to result in more expensive units and longer

deburring in mold fabrication.

measurement times. There are two reasons why imaging-type7)

measurement takes a long time: (1) Image processing of the entire

10nm step feedscreen takes time, and (2) Because the phase of the high-speed
rotating tool cannot be known when shooting, shooting must be

Special Article

the tool, which is a major barrier to achieving high-precision
Introductory NoteFig. 4 shows the response waveform for a 10nm step feed

performed repeatedly until the photo with a required phase is taken.
For (2), because the aerostatic bearing is manufactured in-house, aidentify the phase during high-speed rotation, making it possible tocomplete the measurement with a minimum number of images.
Fig. 4 10nm step response at machining point

Technical Paper

rotation sensor for phase recognition can be built into the spindle toFurthermore, minimizing the number of shots enables shorter times
required for image processing, allowing for faster processing. Fig. 5

Machining Technology

shows the appearance of FormEye during measurement. FormEye
can be installed and maneuvered in the same way as existing tool
length measuring instruments, and no special treatment is required.

machining. These are form accuracy, which indicates the correctness

Fig. 6 shows the measurement results for the tool contour. Theof the form, and surface quality (roughness), which indicates themeasurement results show that even a brand new tool has an error

specularity of the surface. In the field of ultra-precision milling, inof about 4 µm from the ideal round shape, which directly leads to aaddition to high-precision positioning of the machine itself, highmachining error. Also, this measurement function enables step-by-form accuracy has been achieved by calculating the correct tool pathstep monitoring of the detailed progression of damage to the tool

using 3D CAD/CAM with high calculation accuracy, and high surface

edge due to wear or other factors after machining, enabling accuratequality has been achieved by using a high-speed rotating spindle totool life management.8)

New ProductTwo main evaluation criteria are used for accuracy in ultra-precision

Technical Report

4

minimize chip formation and to reduce workpiece deformation.
SeriesHowever, current machining technology is not adequate for bipolar
plate molds requiring high form accuracy, and so we developed amachining technology which corrects the accuracy error componentof ball end mills to achieve even higher accuracy.

Patent News

4.1

High-Precision Tool Shape Detector FormEye

Tool measuring devices are installed in conventional machining
centers to measure the position and diameter of rotating tools formachining. The UVM series also uses a line sensor type toolFig. 5View of FormEye measurement

Prepared Critiquemeasuring instrument, which has the capability to measure thecontour of the tool itself. However, in the conventional methods formeasuring the tool contour, there is a large interior error on themeasuring instrument side when the line sensor is switched between
horizontal and vertical, resulting in a large step near the 45° angle of

Shibaura Machine Engineering Review

44Introductory Note

Blue: Before machining
Red: After machining

Max. value of difference from
ideal shape
Max. value of difference before
and after machining
Corner radius approx. value

correction not returning to CAM" where 3D model correction and
NC data re-creation are unnecessary. This enables significant
reductions in loss of production time from non-machining processes.
Conventional machining process
NC
dataMax. diameter
3D modelSpecial Article

Fig. 6

4.2

Tool contour measurement results(Model correction)

Tool Path Vector Correction

NC data calculation

Machining

Measurement(Tool radius value
correction and CAM
recalculation)

Proposed process with tool
path vector correction

Even in ultra-precision milling, the machining process consists ofEnd
Correction amountbased on machining
surface angle(1) Model creation in 3D-CAD, (2) Machining path generation inTechnical Paper

CAM, (3) Actual machining, and (4) Measurement analysis. FormEye

Tool shape measurement by FormEye

has made it possible to obtain accurate tool contour data, but

Fig. 7

Schematic diagram of tool path vector correction

currently, no matter how high the computational accuracy of 3D
CAD/CAM, only an ideal shape of a perfect circle can be defined fortools. Therefore, if an error of 4 µm is found in the actual tool contour,

5

Machining Verification

Technical Report
New Productas shown in Fig. 6, the error is directly transferred to the machined

Machining verification of the bipolar plate form was conducted

workpiece as a form error component. If the tool protrudes from thewith the aim of improving the form accuracy using FormEye andperfect circle, which is the ideal shape, the machined workpiece will

tool path vector correction. The 3D model and cross-sectional view

be over-cut. However, if the tool is receded from the perfect circle,of the bipolar plate form for machining verification are shown in Fig.

the machined workpiece will have uncut sections. In order to correct

8. The workpiece material was stainless steel for molds (HRC52), andthis error, information is needed on which direction and how far to

the tool was a cBN ball end mill (R 0.5 mm). Fig. 9 shows the contour

retract or advance. Since FormEye provides information on theaccuracy of the ball end mill and the tool correction amountunevenness of the tool contour, it is only necessary to identify whichobtained by FormEye's tool shape measurement. The correction

position of the tool is acting at each selected machining point onamount calculated from the tool contour is minimal around 0° at thethe workpiece surface.

tool rotation center, and increases toward the periphery, reaching a

SeriesPatent News
Prepared Critique

To solve this problem, we developed software which provides anmaximum of 2.5 µm around 90°. Therefore, when machining without

error correction function called "tool path vector correction." In toolcorrection, the form accuracy will be 2.5 + α (effect of wear orpath vector correction, 3D CAD data is used to identify each contact

disturbance) µm, and as the angle of the workpiece approaches thepoint of the tool and provide information on which direction to

90° vertical wall, over-cutting due to tool contour error is expectedmove the tool. Fig. 7 shows a schematic diagram of tool path vector

to occur. Using this tool, a machining test was conducted to compare

correction. In the conventional process, a tool radius value is input

the correction effects with and without tool path vector correction.

to the 3D model to calculate the NC data for machining. If the result

The form accuracy of a cross section of the machined surface wasdoes not pass the subsequent analysis, it can take nearly 100 hours

measured by a FormTalysurf PGI850A (made by TAYLOR HOBSON).

to modify the 3D model and recalculate the NC data by inputting an

Fig. 10 shows the machining results without vector correction. The

optimum tool radius value. Furthermore, if the machining results areform accuracy is -3.2 to +0.2 µm (PV : 3.4 µm), which is a large error

not satisfactory, this corrective machining routine must be repeatedfrom the design value and does not meet the required accuracy.

several times, resulting in a tremendous loss of production time. In

While the workpiece surface is cut without error near the 0° angle,

contrast, the process using tool path vector correction automaticallyexcessive cutting is observed as the angle of the workpiece surface

corrects the NC data coordinate values on the machine side based

approaches 90°. Fig. 11 shows the machining results with vector

on the values measured by FormEye, making it a "method of error

correction. The results of machining with vector correction show

45

Shibaura Machine Engineering Review

be requiring nanofabrication technology, there will also be morecorrection has been improved, and a form with almost no error

areas where conventional manufacturing processes cannot be

relative to the design form was obtained. The form accuracy was -0.6

adapted, and so the production process itself needs to be examined

to +0.7 µm (PV : 1.3 µm), which is less than ±1 µm, which is required

beyond the existing framework. We will continue to identify needs

for bipolar plate molds.

from new perspectives and strive to expand the application scope ofIntroductory Notethat the phenomenon of over-cutting seen without vector

nanofabrication technology for manufacturing.

1) Japan Automobile Manufacturers Association, "Japan's Automobile
Industry 2020," 30.
Fig. 8 3D model and cross-sectional shape

Special Article

References

2) H. ONAKA, Development of Fuel Cell Vehicles at Toyota, Hydrogen
Energy Systems 34, 2, (2009) 10-17.
3) A. MIYAZAWA et al., Development of a New Compact High-powerand Low-cost Fuel Cell Stack, Society of Automotive Engineers ofJapan 40, 5, (2009), 1267-72.

Technical Paper

Tool correction amountSpecification
tool radius

4) H. NAKAJI et al, Development of High performance and Low cost
Fuel Cell stacks, Production and Technology 68, 2, (2016), 72-75.

jp/tech/auto/CLARITY/five_seater.html (accessed Oct.18.2021)
Fig. 9Tool correction amount

Machiningform6) Shibaura Machine Co., Ltd., ULC/ULG Series: http://www.toshiba-

Technical Report5) Honda Motor Co., Ltd., CLARITY Fuel Cell https://www.honda.co.

machine.co.jp/jp/product/nano/lineup/ulg_lg/index.html
Design form

(accessed Apr.12.2021)

Mold Machining Using Ultra-Precision Machining Centers, Mold
Technology, February 2021.
Form error
Fig. 10 Cross-sectional form accuracy without vector correction

New Product7) A. AMANO, Technology to Improve the Accuracy and Efficiency of8) Y. MUROFUSHI, Importance of On-machine Tool Shape Measurement
and FormEye, a High Precision Tool Shape Measuring Instrument,
Mold Technology, June 2021.
SeriesForm error
Fig. 11 Cross-sectional form accuracy with vector correction
Patent News

6

Conclusion

This paper describes one example of the development of
Prepared Critiquemachining technology for high-precision forming of bipolar plates
for fuel cell stacks. In addition to this case, many other industrial
products are improving their performance at a remarkable pace,
and the component parts are becoming significantly more precise
and miniaturized. Consequently, while more and more markets will

Shibaura Machine Engineering Review

46

Technical Report

Introductory Note

Extended Battery Life of the Resolver Multi-Turn ABS and
its Contribution to the Circular Economy
In recent years, growing global interest in the SDGs has become a major
trend, accelerating the effective use of resources and carbon-free
initiatives in many countries. Our BS servo system has an absolute

Special Article

position detection system called the "Resolver Multi-Turn Absolute
System" which applies a resolver to detect the position of the servo
motor. However, since the circuit is driven by a battery during a power
failure, power consumption determines the life of the battery. In thisresolver multi-revolution ABS system, we have made efforts to savepower, extend the maintenance period by extending the battery life, andControl Systems Company
Control Systems Engineering
Department

Control Systems Company
Control Systems Engineering
Department

Narutoshi YOKOKAWA

Kazuya WATANABE

Technical Paper

reduce the number of primary batteries used. In this paper, we introduce
our efforts.

Technical Report

1

Introduction

With the growing interest in the SDGs, practical ways to realize a"Circular Economy," have been attracting attention. A circularbatteries disposed of annually. The beneficial environmental impactof recycling is greater than that of general disposal, but the view
remains general disposal of batteries is appropriate, so recycling has
not been expanded.

New Producteconomy refers to efforts to minimize the input of new resources

Under these circumstances, one of our efforts to contribute to theand raw materials, creating new value in what is already being used,recycling-oriented economy is to reduce the amount of battery

and minimizing the generation of waste.

waste by saving power. In this report, we introduce our efforts to

At present our BS servo system has an absolute position detection
system called "Resolver Multi-Turn Absolute System" (hereinafter

date to reduce the power consumption of the resolver multi-turnABS system.

called "ABS"). This system maintains the machine home position by
Seriesmeans of battery backup in case of power failure or when the poweris turned off. The advantage of this system is the machine coordinates are remembered when the power is turned on again, so there
is no need to search for the origin at startup. Since the circuitry
which constantly monitors the motor movement continues toPatent News

operate with battery backup in case the machine is moved during a
power failure, this power consumption determines the life of thebattery. Routine maintenance after machine operation requires
Fig. 1

replacement of the battery before it reaches the end of its life. For
Prepared Critiquethis reason, primary alkaline and lithium batteries are often used,

BS servo system

2

Past Activities

most of the used batteries are discarded. According to an estimate

2.1

Resolver Multi-Rotational ABS System Featuresby the Battery Industry Association of Japan, 49,000 tons of batteries

We first introduce the resolver multi-revolution ABS system. The

are disposed of annually in Japan, which translates to 2.1 billion AA

main feature of the resolver multi-revolution ABS system is thewhich are inexpensive and readily available even overseas. Currently,

47

Shibaura Machine Engineering Review

construction of an absolute position detection system at low cost

2.2

without external sensors, without compromising the overwhelming

The history of power consumption reduction from the beginningenvironmental resistance (heat resistance, vibration resistance,of development in 2002 to the present is shown in Table 2. The

shock resistance, and long life). In other words, during a power

development steps were carried out in conjunction with the

failure, the resolver body continues to monitor the angle anddevelopment of the BS servo system series, and the battery life has

number of rotations as it does when the power is turned on. In

been steadily extended. At the beginning of the development thegeneral, a separate magnetic sensor would be externally mounted

optimal conditions were derived from the trade-off between theand an electronic circuit provided in the sensor section, but thepulse width of the excitation pulse, the signal-to-noise ratio of themerits of the resolver are greatly diminished when an electronic

received signal, and the allowable power consumption. In addition,

circuit is added to the motor sensor because the environmental

power recovery of the pulse excitation was implemented to reduce

resistance performance is reduced. For the characteristics of thethe power consumption within that range. At that time, it wassensor alone, Table 1 shows the comparison with our serial encoder.

extremely difficult to detect wire breakage within the limitations of

The resolver's values for environmental resistance and long-distance

low power consumption, but we cleared this problem by usingtransmission are based on the specifications, and its performance isreverse excitation pulses.

History of Power Consumption Reduction
Introductory Note
Special Article
Technical Paper

This was followed by improvements in the performance ofeven higher than the values.

capacitors and lithium batteries used in mobile information

Table 1 Comparison of sensor characteristics

terminals, and the emergence of ultra-low power consumption

ResolverSerial encoder

Allowable rotation speed

10,000 min-1

6,000 min-1

Resolution

24,000 P/rev

131,072 P/rev

Angular error

8 min

1 min

Vibration resistance

20 G

10 G

Shock resistance

100 G

20 G

were also able to reduce the number of primary batteries from theAmbient operating
temperature
Maximum transmission
distance-55 ～ 155 ℃-10 ～ 85 ℃

original three to one, thus reducing the amount of primary battery

120 m

30 m

CPLDs (Complex Programmable Logic Devices) and CPU devices,which we also adopted to further reduce power consumption. As aresult, we were able to triple the maintenance period of the resolver

Technical ReportItemmulti-revolution ABS system from the initial development stage. We

New Productwaste to 1/9.

With the latest BS servo system R series, it is possible to build aresolver multi-revolution ABS system by simply connecting a battery
and changing some parameters, without adding any optional
Seriesboards, by selecting a resolver compatible servo amplifier andmotor.
Table 2Development StepsHistory of power consumption reduction in resolver multi revolution ABS system

Main approaches
・Pulse excitation power recovery
・reverse excitation disconnection detection

2008 Development of X series

・Ultra-low power consumption CPLDs adopted

2012 Development of S series

・Analog circuit reduction2018 Development of R series・Addition of electric double layer capacitor

Patent News

2003 Development of V series

Battery life*1)
2 years
3 parallel AA lithium battery

4 years
4.5 years

1 AA lithium battery + capacitor

6 years

Shibaura Machine Engineering Review

Prepared Critique*1) The condition for calculating the service life is when the power of the servo system is turned on for 12 hours and off for 12 hours.

48

2.3

Specific Approaches

excitation voltage waveform. In the case of pulse excitation, the pulse

Introductory Note

The following sections describe concrete examples of implemen-

width of driver S1 is set to a few µs, and S3 is set to half the width.

tation.

Since the resolver has a large inductance, widening the pulse
width increases the current. As a result, current flows in the cableSpecial Article

2.3.1 Power Recovery for Pulse Excitationand the resolver itself, and the signal-to-noise ratio of the signal fed

A simplified diagram of the resolver excitation circuit is shown inback from the resolver is improved, but power consumption also

Fig. 2. Our excitation system uses two-phase excitation and one-increases. To improve this situation we have devised andphase output, and two-phase excitation uses PWM (Pulse Width

implemented a function to recover the excited energy to the power

Modulation) excitation because the accuracy of the voltage amplitude

supply. Fig. 4 shows the mechanism of energy recovery. Each FET

and phase difference of 90 degrees affects the detection accuracy. For

represents the output stage of the driver shown in Fig. 2.

this reason, a bus transceiver is used to drive excitation. Normally,
continuous PWM excitation is used for angle detection while the(A) State before applying excitation pulse

Technical Paper

power is on to achieve high accuracy and high resolution, but when

Drivers S1 and S3 both output Low voltage, and FETs (Field Effectthe power is off, intermittent pulse excitation is used because low

Transistors) Tr2 and Tr4 connected to the GND are turned ON, while

power consumption is necessary. Fig. 3 shows an example of the

Tr1 and Tr3 connected to the power supply are turned OFF.
PWM excitation

Technical Report

S1

S3

Pulse excitation
New ProductFig. 2 Simplified diagram of resolver excitation circuit
S1

S3

SeriesFig. 3 PWM excitation and pulse excitation(A) State before applying(B) After applying excitation pulse

Patent News
Prepared CritiqueFig. 449

Shibaura Machine Engineering Review

Recovery of excitation energy(C) When excitation pulse is OFF

(B) State with excitation pulse appliedin voltage resistance and capacity, low cost, miniaturization, andreduction of circuit current consumption made it possible. Currently,

voltage is output, voltage is applied to the resolver coil, and current

only a few users are equipped with these supercapacitors, but we will

begins to flow in the coil. At this time, energy U is stored in the coil.

consider making them standard in the future.

Introductory Note

When Tr2 of driver S1 is turned off and Tr1 is turned on, a high

U: Energy (J)L: Inductance of the coil (H)Special Article

I: Current (A)(C) State when the excitation pulse is turned off
After the pulse width time has elapsed, the driver S1 is set to LOW
voltage to stop the application of voltage, but at the same time, Tr4
is turned OFF and Tr3 is turned ON to set the driver S3 to HighTechnical Paper

voltage. Then, the current in the coil flowing in the state of (B) goes
through Tr3 and returns to the power supply. This is equivalent to
Fig. 5

recovering the energy of the coil to the power supply. In fact,

Application circuit for electric double layer capacitor

although there are losses such as resistance components of the coiland ON resistance of the FET, 70 to 80% of the excitation energy canTechnical Report

be recycled by this recovery. By recycling the energy which would
be lost in resistance and released as heat if left as is, we are
implementing a circular economy.

2.3.2 Application of Electric Double Layer Capacitor
New Product

When industrial machines operate 24 hours a day, they are always
in operation except for a few weeks a year during year-end holidays
and summer holidays, and the actual battery life is extended
because the power supply from the battery is small during power
Fig. 6outages, etc. On the other hand, if the power supply is turned on
during the day and off at night, the battery power is used during the

installed in the amplifier.

3

Conclusion

In this report, we have described various measures to reduce thepower consumption of the resolver multi-revolution ABS system tocapacitor, and Fig. 6 shows a photograph of the implementation.

extend battery life. We believe we can continue to contribute to the

Even when the power is turned off, provided the voltage of thecircular economy by efficiently even with the energy of AA batteries,

capacitor remains, no power is supplied from the battery. The electricby using it with ingenuity and without waste. We have not been able

double layer capacitor is slowly charged while the power is ON toto mention wire breakage detection and other technologies in thisprepare for the next power OFF period. However, when the power

report, but please refer to the patent gazette for details. 1)~3)

Patent News

Fig. 5 shows the application circuit of the electric double layer

Seriesnight. This power is supplied from an electric double layer capacitor

Electric double layer capacitor mounting board

supply is turned off for as long as 10 days during weekends, year-end
References

all. However, the battery life of six years was achieved by reducing the1) Patent No. 4364569: Resolver signal processing device

number of lithium batteries from three in parallel to one. Although2) Patent No. 4364570 Resolver signal processing device

electric double layer supercapacitors have existed since the beginning3) Patent No. 4364571, Resolver signal processing device

Prepared Critiqueholidays, and summer vacation, it is not possible to use the battery atof development, it was difficult to apply them, but the recent increase

Shibaura Machine Engineering Review

50Technical Report

Introductory Note

Training Junior Employees using Digital Technology : Standardized
Documents in Video Format
In recent years, the widespread use of tablets and other mobile devices has made it possible toeasily view large video files at worksites. We are using these tablets to give operators access tostandardized documents (formerly text-only) in video format, featuring easy-to-understandSpecial Article

photos, footage, and supplementary text to cover the same content as the original documents.
These documents can efficiently convey nuances that are difficult to convey only in text format ina short time, and the technical terms that are used in the field of manufacturing can be recognized
and understood. More than 50 standardized documents have been converted to video manuals
so far through our efforts from 2017.

Technical Paper

1

Introduction

Production Center
Machinery & Production
Engineering Department

Ryosuke FUJIMOTO
operating standards to junior operators. But with the widespread
availability of tablets and other mobile devices which can be used at

Technical Report

Seniors are expected to make up a third of Japan’s total population

worksites, we have been able to show large video files on the floor.

by 20301), eroding the nation’s working population and causing

Our company has therefore begun using mobile devices to create

severe labor shortages. The working population had already fallen

video versions of our standardized documents (video manuals)

by an average of 180,000 people over the previous year in fiscal

which use pictures and video coupled with supplementary text2020 , so Japan is already facing labor shortage challenges. At the

explanations. This report describes the makeup of the video manuals

same time, employers must be willing to take on a workforce which

we use at our worksites and our results.

2)

is more diverse than ever before, lending critical significance tooperating standards. The issues covered in this report are relevant to
New Producttwo Sustainable Development Goal targets: 4.3 (substantially2

Implementation

increase the number of youth and adults who have relevant skills,

Our basic rules for creating video manuals include standards forincluding technical and vocational skills, for employment, decent

ensuring safety, ease of use, and quality. We also include standards

jobs, and entrepreneurship) and 9.4 (greater adoption of clean andfor target operation times to ensure efficiency. Fig. 1 shows ourenvironmentally sound technologies and industrial processes).

procedure for creating video manuals. We start by selecting a video

One of the challenges we face in the Machinery & Production
SeriesEngineering Department at our Production Center is transferring

to create (target operation), creating and revising a storyboard,
recording the video, and then editing and revising the footage.

skills to junior operators. The specialized terms used at worksites
have nuances which are difficult to communicate in written form ororally, so the junior employees vary widely in terms of their levels of

Select target
operation

Createstoryboard
Fig. 1

understanding and how long it takes them to acquire thisRecordvideo

Edit video

Procedure for creating video manuals

Patent Newsknowledge. There are also situations where technical skills are

Prepared Critiquedifficult to express in written words, making it essential to instruct2.1

people verbally. And yet, even oral communication ultimately only

Creating a storyboard is a critical part of the process, as it gives a

explains the actions themselves, with the purpose of the operation

clear picture of the overall flow of the video manual by visuallyoften lost. Once this happens, operations are subject to ad hoc

indicating the screen configurations for each clip. Storyboards

shortcuts which are intended to support efficiency but run the risk

consist of a job (title), basic operations, required tools, detailedof triggering quality issues which were never problems before.

operations, and an inspection step. Storyboard creators also consider

At Shibaura Machine, we used to use written (text format)
standardized documents and oral explanations to communicate

51

Shibaura Machine Engineering Review

Creating the Storyboard

the amount of time needed for each clip. Fig. 2 shows an example ofa storyboard for a video on how to maintain a digital dial gauge.

operation or subject so the video is easy to understand. Both film
Basic operations

Required tools

and stills are used as needed, as still images make it easier to explain
tools or other non-moving components of the operation.
(*1, *2 : iPhone and iPad are trademarks of Apple Inc.)

Inspection step

Detailed operations

Introductory Note

Job

Detailed operations
Special Article

Detailed operations…

Technical Paper

Fig. 2

Example of a storyboard

Fig. 3The basic operations clip divides the overall job into major steps.

2.3

Video recording

It also includes explanations of any technical terms used. In this

Next, an iPhone/iPad video creation and editing app (Photron’s

example, the basic operations are cleaning, confirming external

Mobile Video Creator) is used to edit the footage. Editing can take

operation, and measurement. The required tools clip shows photos

place at the worksite since the same iPhone or iPad used to take theof all the tools needed for the operation as well as their names invideos is also used for the editing process (Fig. 4).

Technical Report

Editing the Video

text. In this example, the operator will need an ICH cleaner, shop
New Productcloth, and deerskin cloth. The detailed operations clips include
detailed explanations designed for inexperienced operators. The
inspection step explains how to inspect the work and provides pass/
fail criteria along with a film of a perfectly-performed operation. In
this example, the failed operation is “not wiping away with the ICH
cleaner because it makes the transparent plastic cover foggy andSeriesmakes the gauge hard to see.” The pass operation is “wiping thegauge head and other components with the deerskin cloth so dust
does not adhere to them.” Each detailed operation describes thecorresponding inspection step.

Fig. 4

Video editing

All members involved in the job participate in the making of theVideo editing is also guided by the storyboard, with every effort

revisions, and additions to make sure frontline workers are on board

made to keep the video to around three minutes total. The three-with the video and can use it on site.

minute standard allows operators to focus on the video while they

Patent News

storyboard, which then serves as a springboard for discussion,

are on the job. For longer operations, content is split up into different

Recording the Video

scenes to keep the videos from dragging on. Fig. 5 shows the

The required footage is recorded quickly while consulting thestoryboard alongside the edited video.

storyboard. As shown in Fig. 3, an iPhone or iPad is used for the*1*2

recording. Operators are consulted to determine the recording
angles or distances which will best indicate the key points of each

Shibaura Machine Engineering Review

52

Prepared Critique

2.2

Storyboard

Edited video

Introductory Note

Job

images. They can also add music or narration tracks to effectively
demonstrate key points. Once all editing tasks are complete, thefinal version is reviewed using a preview function and saved.
Videos are kept to an absolute minimum to speed up processing
time and limit storage demands. Video manuals are saved at 960 x
540 and a bit rate of 4 Mbps. At this rate, the data load per second is
4 megabits/8, or 0.5 megabits per second.

Special Article

Basic operations

3

Results and Outlook

Experienced operators use standardized documents to transmit
skills to junior operators primarily at worksites during on-the-job
Technical Paper

training sessions. This means both those teaching and learning thematerial are often pressed for time. Use of the video manuals allows
Required tools

skills to be efficiently transmitted to multiple operators in a
streamlined way when there isn’t enough time to do so on the job.
Fig. 6 shows operators using the video manual at a worksite.

Technical Report
New ProductDetailed operations

SeriesFig. 6

Watching a video manual at a worksite.

Prior to using iPhones and iPads to create video manuals, we used
Inspection stephome video cameras coupled with desktop video editing software.
The video manuals were still highly valued, but each one took about

Patent Newstwo days to create. Switching to the iPhone and iPad video creationand editing app, however, has allowed us to shorten video creation
time to around three hours. And because the same device is used toedit and film the videos, revisions and additions can be made on the

Prepared CritiqueFig. 5The storyboard and edited video

spot - further streamlining the process.
We can achieve quality management through the implementation

As shown in Fig. 5, the edited video faithfully replicates thestage of Total Quality Management (TQM), based on the Systems

content in each storyboard clip. The editors select the footage which

component of the ISO 9000 series. The Union of Japanese Scientists

matches the parameters of the storyboard and then insert text andand Engineers (JUSE) has issued a list of action steps for TQM and

53

Shibaura Machine Engineering Review

quality management activities related to the ISO and TQM

to taking operations from stage three to stage four within a total of
five steps. The action items listed are (1) thorough education andtraining in all departments based on rules and standards, (2) clear

3. Guide to Taking TQM and Quality Management Activities to the
Next Stage, Union of Japan Scientists and Engineers (2014)
4. OODA Loop, Chet Richards (translated by Tsutomu HARADA), Toyo
Keizai (2019)

Introductory Notestandards.3) According to this document, standardization is the key

Bureau of Japan (2021)

enactment and revision of rules and standards, (3) seeking root
Special Article

causes (of both occurrence and outflow) and preventing recurrence,(4) implementing “go and see” management and change
management, and (5) permeating standardization and daily
management throughout the organization. The video manuals have
proven to be an effective method of overcoming the hurdles toachieving these standardization-related targets at our worksites.

Technical Paper

Casting and machining processes can involve fluctuations andsudden changes which must be swiftly addressed on the plant floor.
The key here is standardized operations. If every operator has thesame streamlined knowledge, then they should be able to properly
implement the OODA Loop (Observe, Orient, Decide, Act)4) even at

Technical Report

worksites which undergo dramatic situational changes.
Our Production Center will continue to use digital technology to
improve the quality of its manufacturing practices, aiming for
efficient production which raises the bar on quality, cost, anddelivery (QCD) with a small workforce.

New Product4

Conclusion

We create video manuals using a four-step process: selecting thetarget operation, creating a storyboard, recording the video, andediting the video. Using mobile devices with a video creation andSeriesediting app allows us to move from filming to editing in a shortperiod of time. Using these video manuals at worksites has allowed
us to transmit skills to multiple operators in an efficient, streamlined
way - even when we are pressed for time. In this way, video manuals
powered by digital technology have proven to be an effective

Patent News

method of overcoming the hurdles to implementing standardized
operations at worksites, thereby enabling high-level quality
management and efficient production in line with ISO 9000 series
and TQM standards.

Prepared Critique

References
1. Population Projections for Japan, National Institute of Populationand Social Security Research (2017)
2. Labor Force Survey (Basic Statistics) 2020 Averages, Statistics

Shibaura Machine Engineering Review

54Technical Report

Introductory Note

Development of an AI-based Function to Monitor the State of Machining
during Cutting in the Double Column Type Machining Center
Human senses play an important role in the processing field of the manufacturing industry.
There are many craftsmen in Japan who have mastered the technique, called Takumi (master
artisan), but it is almost impossible to pass on their technique to future generations in a nearlySpecial Article

perfect state. This research was conducted with the aim of making AI (artificial intelligence) learn
the senses of an operator to reproduce his/her discernment ability when operating a machine
tool as a subject. In particular, much information is obtained from sound during cutting. Therefore,
this research focused on 3-axis acceleration during machining. As a result, a high machining state
accuracy has been achieved as evidenced by the data we received.

Technical Paper

1

Introduction

Research & Development Center
Research & Development
Department

Taku HOSHIYA

acceleration sensor installed on the side surface of the spindle, andthe processed data was input to AI.

In machining, the state of ongoing machining is judged based on

Technical Report

the information from the operator's five senses including sight and2.1.1 Acquired Data

hearing. However, the acquisition of a sense-based discernment

Fig. 1 shows an example of acceleration data acquired during

ability is impossible in a day and requires enormous experience. Thismachining. In Fig. 1, a difference is seen between the tool idle region

research focused on a supervised multiclass classification technique(gray area), the machining introduction region (orange area), thein deep learning to replace with AI the discernment ability ofstabilized machining region (blue area), and the machining closing

humans acquired through experience.

region (green area).

New Product
SeriesBy making AI learn the discernment ability, even people without

In this study, first, a data set for the stabilized machining region

skills or experience will be able to perform stable processing, which(blue area) and a data set for the other regions (hereinafter referred

improves productivity and leads to relaxation of employment

to as unstable data) in Fig. 1 were created. Options for differentiating

conditions. The 8th item in the SDGs, "Decent Work and Economic

the three states during machining in the stabilized region; (i) normal

Growth", aims at achieving "full and productive employment",state, (ii) chipping state, and (iii) chattering state, were set. AI needs

protecting "labor rights", and promoting "safe and secure working

to differentiate between the four options, including (iv) unstableenvironments" by 2030 for all workers including migrant workers

data, to determine which machining acceleration data corresponds

irrespective of their age and gender. Therefore, it becomes possible

to which state.

to contribute to the above-mentioned SDGs if employment

Idle region
Machining
introduction region
Stabilizedmachining region
Machiningclosing region

productivity as a result of this research.
Patent News

2

Dataset Overview

2.1

DatasetAcceleration

conditions are relaxed while ensuring a high-level of economic

For supervised multiclass classification, input data to be given to
Time [s]Prepared Critique

AI and training data showing what kind of data the input data is, arenecessary.
In this research, the object was machining by a double-column

Fig. 1

Acceleration data during machining

2.1.2 Preprocessing of Data

type machining center (MPF-2614FS). Certain data processing was

As a method for analyzing acceleration data, the FFT (Fast Fourier

performed for the acceleration data acquired from the 3-axis

Transform) was used in this research. This time, acceleration data per

55

Shibaura Machine Engineering Review

second was analyzed, and binning was performed first. Binning is aa) Calculating the correction coefficient of the number of blades
The correction coefficient of the number of blades is a coefficient(bin width). It is possible to extract the characteristics of the FFT

for correcting the difference in the number of blades which differs

result data (1 to 3.2 kHz) described above by performing binning forfor each tool. The reference number of blades was set to eight

100 sections for every 20 Hz (bin width). The analysis was performed

according to Table 1. The formula for calculating the correction

for 1 to 2 kHz.

coefficient of the number of blades is shown as the equation (2).

Introductory Note

method to calculate the representative value in a certain section

This time, it was thought that the characteristics of the FFT result

representative value in the section.

Special Article

could be maintained by using the maximum value as theCorrection coefficient of the number of blades=
Actual number of blades / Reference number of blades (2)The milling cutter, a tool used in a machine tool, has multiple
parameters such as the number of blades, rotation speed, andb) Calculating the correction coefficient of rotational speed
The correction coefficient of rotational speed is a coefficient forparameters fluctuate. To optimize the versatility of AI, preprocessing

correcting the difference in rotation speed which differs for each

which absorbs the effects of parameter fluctuations is important. In

machining operation. The reference rotational speed was set to 500

this research, we performed binning and synthesis/normalization ofmin-1 according to Table 1. The formula for calculating the correction

binning results as pretreatment.

coefficient of the rotational speed is shown as the equation (3).

Technical Papermachining direction. The nature of acceleration changes as the

For binning, in expectation of improvement of general versatility,

depends on the rotational speed during cutting and the number ofTechnical Report

we focused on the forced vibration during machining, which

Correction coefficient of rotational speed=
Actual rotational speed / Reference rotational speed (3)blades of the tool. The formula for calculating the forced frequency
is shown as the equation (1).

c) Calculating correction coefficient of bin width
Based on the equations (2) and (3), the formula for calculating the
Rotational speed [min ]×
60 [s]
Number of blades（1）It can be seen in the equation (1) that the forced frequency
depends only on the rotational speed and the number of blades. In

coefficient for adjusting the bin width and the correction coefficientof rotational speed is shown as the equation (4).
Correction coefficient of bin width=
Correction coefficient of the number of blades ×
Correction coefficient of rotational speed

New Product

Forced frequency [Hz]=

-1

(4)

this research, reference values were set for the number of blades,

fluctuating parameters. Table 1 summarizes the reference values.

d) Adjusting the bin width
The bin width is adjusted using the equation (4). The equation

Seriesrotational speed, forced frequency, and bin width to deal withused for the adjustment is shown as the equation (5).

Table 1 Reference parameters

8

Reference rotational speed

500 min-1

Reference forced frequency

66.67 Hz

Reference bin width

20 data items

Bin width=
Reference bin width ×Correction coefficient of bin widt (5)Patent News

Reference number of blades

The above is the process of adjusting the bin width.
Since the object of analysis in this research is 3-axis acceleration,

This means the value of the forced frequency will be stored in thethe same processing was performed for each axis. Fig. 2 shows anfourth section (61 to 80 Hz) if binning is performed with a bin width

example of binning in the range of 0 to 200 Hz. The red dashed lineof 20 Hz. In this research, the bin width was adjusted so the forced

in Fig. 2 indicates the bin width, and the maximum value therein isfrequency would be stored in the fourth section under all conditions.

the representative value.

The process of adjusting the bin width is shown below.

Shibaura Machine Engineering Review

56

Prepared Critique

As shown in Table 1, the reference forced frequency is 66.67 Hz.

Acceleration

Introductory Note

FFT data
Bin data

Synthesized data (r) = √ (x'2+y'2+z'2 )(7)At this time, the maximum value of the synthesized data may
differ depending on the machining direction. Therefore, by dividing
the synthesized data by the maximum value as shown in theequation (6), the synthesized data was also normalized so it wasSpecial Article

Frequency [Hz]Fig. 2composed of a value of 0 to 1.

FFT and binning

Based on the above, in this research, deep learning was performed

2.1.3 Effect of Cutting Direction

using 100 items of normalized synthesized data as input data. As an

Cutting process at a processing site is not only single-axis cutting

example, Fig. 3 shows a graph of synthesized data which has beensuch as single-plane cutting.

normalized under normal conditions.

consideration of the cutting pattern. In this research, it wasconsidered that highly generalized AI could be created by making AI
learn created data obtained by reducing the effects of cutting
direction by normalizing and synthesizing the X-axis, Y-axis, andTechnical Report

Z-axis binning data. The process is shown below.

Input value given to AI

Technical Paper

It is clear a huge amount of time is required to collect data ina) Normalization of 3-axis binning data

Bin number
Fig. 3

There is a wide variety of vibrations during machining, and theSynthesized data

maximum acceleration recorded by each vibration type varies
New Productdepending on the data. This may lead to AI recognizing the difference

2.1.4 Training Datain the magnitude of the maximum value, which is a problem when

As explained in section 2.1, AI learning requires input data to beconsidering generalization. In this research, it was decided that unifying

given to the AI as training data. First, the input data given to AI was

the maximum acceleration for all data would solve this problem. The

normalized as described in section 2.1.3. With respect to training

equation used for the normalization is shown as the equation (6).

data, the classification of four states of machining was utilized in thisresearch, and it was found from Fig. 1 that training-labeling of stable

SeriesNormalized data (x',y',z')=(Binning data for each axis)(Maximum value of 3-axis binning data)

and unstable regions was relatively easy. The stable region was(6)

training-labeled based on the determination of the machining
operator in execution of a cutting test.

In this way, by using the equation (6), normalized data having amaximum acceleration of 1 is created. Since the amplitude was set
Patent Newsto an absolute value in FFT, the normalized data is composed of avalue of 0 to 1.

3

Results and Consideration

Table 2 summarizes the relationship between the discernment
results of an AI model using verification data and the training labels.

b) Synthesis of 3-axis normalized data

As shown in the thick frame in Table 2, all items of the stable

Prepared Critique

As described in this section, reducing the effects of direction leads

region (normal, chipping, and chattering states) judged as mis-

to improvement of generalization. In this research, it was decided

discernment are "unstable". This is because although current

the effects of direction could be reduced by synthesizing theunstable data corresponds to the areas where the acceleration isnormalized data for each axis. The equation used for the synthesis isunstable, the acceleration data in the stable state is mixed in during

shown as the equation (7).

data processing in some cases; as a result, the characteristics of the

57

Shibaura Machine Engineering Review

characteristic data which was extracted from 3-axis acceleration

this is to exclude the range where the boundary between the stabledata and preprocessed to minimize the effects of parameters.

region and the unstable region is ambiguous at the time of data

However, the discernment accuracy shown this time has been

extraction by combining such range with information such asverified within the data we currently have, so it is necessary to verify

spindle status from NC. By this, it is considered possible to reducethe versatility by using more data in the future. In addition, trends ofthe number of misdetections.

more complex data groups may be shown at the stage of verifying

Introductory Notestable region are also included for learning. A possible solution to

the generalization, so it is possible the final discernment accuracy
will be lower than the current one. Although there are still issues toConclusion

be solved, we intend to proceed with research on the added value ofThis report described research showing it is possible to classify

machine tools for making them more intelligent.

Special Article

4

machining into four states by performing deep learning ofTechnical Paper

Table 2 Discrimination results

Prediction result
Chipping

Chattering

Unstable

Normal

1657

0

0

3

Chipping

0

905

0

1

Chattering

0

0

91

3

Unstable

14

7

3

566

Technical Report

TraininglabelsNormalNew Product

Perspectives Gained from My Workdevelopment of hybrid core cylinders

understanding of cores was naive. Since cores move to press

for die casting molds. Conventional

against the mold and a hybrid core cylinder uses a ball screw, if

core cylinders are controlled only by

the core is affected by an exterior effect such as pressing force,

hydraulic pressure, but hybrid corea positioning error will be caused. Therefore, it is not enough tocylinderselectricallysimply move it back and forth, but countermeasures arecontrolled or controlled by hydraulicneeded. That is what I found. From this experience, I learned thepressure, and the control method

importance of understanding the entire event from various

can be changed depending on

perspectives, such as the action of forces when the machine

which is most suitable. Initially, my understanding of cores was

moves and the characteristics of the machine, not to mention

that they only move in one dimensional direction, so I thought

understanding the superficial aspects of machine operation. I

allowing simple back and forth movement would be enough.

will use this experience to carry out my future work.

Metal & Plastics Industrial MachineCompany
Metal & Plastics Industrial MachineTechnology Department

Koichi KUMAKI

areeitherPatent News

However, as soon as I started my work, I realized mySeriesMy assigned work is currently the

Prepared Critique

Shibaura Machine Engineering Review

58New ProductIntroductory Note

Introduction of Large-Size Electric Injection Molding Machine EC1800SXⅢSpecial Article
Technical Paper

1

Overview

speed when replacing the mold with one having a different moldthickness is extremely slow due to the mechanism. Therefore, when

Amid the background of a declining working population due to aexchanging molds between thin and thick types, the downtime

decreasing birthrate and ageing population, improvements in the(non-productive time) increases, leading to a drop in production

productivity of factories have long been a pressing issue. On theefficiency.

Technical Reportother hand, global interest in SDGs such as the suppression ofenergy consumption towards the realization of a low-carbon society

To resolve this problem, the mold thickness adjustment speed
was improved in the EC1800SXⅢ.

New Productis increasing. High productivity and labor-saving features in an

By supporting the link housing (a component of the moldinjection molding machine are therefore important contributions

clamping device) with a linear guide, the sliding resistance istowards resolution of these issues. We developed the large size

reduced, and by high-speed rotation and high-precision positioning

electric injection molding machine EC1800SXⅢ as a product tocontrol of the servo motor, a drastic increase in the repeating speed

realize this goal.

and stability by the mold clamping force are achieved. A resulting
increase in production quantity is one of the effects of increasing

2

Features

The EC-SXⅢ series of electric injection molding machines

this mold thickness adjustment speed.
Fig. 1 shows a comparison of the mold exchange time for adifference in mold thickness of 700 mm.

Seriesemploys a linear guide in the moving die plate support structure to375 sachieve high productivity by high-speed mold opening and closing
and is top of its class in the industry.

▲ 282 sTime [s]Patent News

special option to achieve even higher productivity.

Link housing movement time
Moving die plate movement time

In addition to this feature, the EC1800SXⅢ can be equipped withnew high-speed mold thickness adjustment specifications as a

Adjustment time

(75% reduction)

93 s
2.1

Shortening of Mold Exchange Time

Resin parts which make up the end product are also becoming
Prepared Critiquemore diverse due to the diversification of consumer needs, and as aresult, the increasing frequency of mold exchange is a significant

EC1800SX
Fig. 1

EC1800SXⅢHigh speed mold thickness
adjustment specifications

Comparison of mold exchange timetrend. Mold sizes are also diverse, allowing molds with a thickness
from 800 to 1500 mm to be mounted in the EC1800SXⅢ. In a typicalCompared to EC1800SX, the time can be shortened by 282 s (75%

toggle-type mold clamping device, the mold thickness adjustment

reduction). Assuming the mold exchange count per day is 10, the59

Shibaura Machine Engineering Review

time is shortened by 172h*1 annually, and an increase in production
Introductory Note

volume by 20,680 shots*2 can be expected.
*1: Number of operating days 220 days/year*2: Molding cycle 30 seconds
On the other hand, to immediately restart production once moldexchange is complete, the heater of the heating cylinder is on
standby in a powered-up state even during mold exchange. The

Special Article

proportion of power consumed by the heater in an electric injection
molding machine is high, so a shortening of the mold exchange
time (standby time) is directly linked to a reduction in power
consumption.
Fig. 2 shows the standby power consumption during moldTechnical Paper

exchange.
Compared to the EC1800SX, the reduction in power consumption
is 1.6 kWh (56%) per hour in the EC1800SXⅢ, so on a converted

Fig. 3

Example of a production processbasis, an annual reduction of about 0.5 tons in CO2 emissions can ispossible.

To support these tasks, the controller “INJECTVISOR-V70” isStandby power
consumption [kWh]In the production plan shown in Fig. 4, a series of actions undermultiple molding conditions and set-up conditions can be set. When

Technical Reportequipped with a production planning function called “INDUSTROL”.
Equivalent to an annual
reduction of 0.5 ton peryear in CO2 emissions

production under molding condition A is completed, set-up(56% reduction)

condition 1 is automatically executed, and when it ends, production

under molding condition B is completed, set-up condition 2 is
executed.

New Productunder molding condition B is started. Similarly, when production

High speed mold thickness
adjustment specifications
Fig. 2 Standby power consumption during mold exchange
Series2.2

Automation of Set-up Work

Every time a molded part is changed, a “set-up operation” toexchange the mold and switch the type and color of the raw resinmaterial needs to be carried out. Since operations and judgments are
Patent News

carried out by the operator, there is a potential risk of human error.
Fig. 3 shows a partial excerpt of the production process.
When production under molding condition A is completed, setup operation (set-up condition 1) is carried out before the next

Prepared Critique

production (molding condition B) is initiated. After production
under molding condition B is completed, set-up operation (set-up
condition 2) is executed.

Shibaura Machine Engineering Review

60Introductory Note

Molding
conditionA

Set-upcondition
1

Molding
conditionB

Set-upcondition
2

Special Article
Fig. 4

Production plan

Technical Paper

Operation icon
Work procedure

Technical Report
Fig. 5

Set-up condition settings

New ProductFig. 5 shows the set-up condition settings. Each operation isvisually represented by an icon, allowing the operator to freely
create a work program by placing the operation icons in the work
sequence. A feature of the system is the ability to intuitively checkthe settings in this way.
Being able to switch the molding condition and configure the set-

Seriesup process beforehand allows the operator to reduce human error,
shorten the work time, and carry out other tasks while the process isbeing automatically executed. Moreover, since this function is highly
compatible with peripheral ancillary devices (automatic moldexchanger, auto coupler/connector), it can easily support

Patent News

automation and labor-saving for switching molded parts.

3

Summary

Prepared Critique

We developed the EC1800SXⅢ as a product which is capable ofgreatly contributing to higher productivity, labor-savings, and therealization of a low-carbon society as cited in our SDGs. Moving
forward, we intend to continue developing injection molding
machines which can meet the needs of the world.

61

Shibaura
Machine Engineering
Review
YutakaMIYAKAWA
Metal & Plastics
Industrial Machine Company, Metal & Plastics Industrial Machine Technology Department
Shibaura Machine Engineering Review

New ProductIntroductory Note

Introduction of the Newest Die Casting Machine DC1300R-E

Special Article
Technical Paper

1

Overview

Die casting is more productive than other casting methods, andits ability is largely dependent on the die casting machine. This
report introduces the die casting machine DC1300R-E, which we

The DC1300R-E is a large high-cycle die casting machine which

Spray descending position(die opening limit)
Fig. 2

Die intermediate position

Die opening / closing intermediate stop

operates at high speed by employing a servomotor to drive die-2) Space saving has been achieved by reducing the size of the tankplate open and close and a pump which fills the accumulator (ACC)

inside the frame, which was made possible by electrification ofat high speed.

die-plate clamping and by modifying the layout of the hydraulic

DC1300R-E offers improved display visibility and operability.

2

motor. The DC1300R-E can be installed in the same space as amachine one class-size smaller. (Fig. 3)

New Product

Equipped with the newest controller TOSCAST-999, theTechnical Report

have developed for improving productivity.

Features

1) By adopting a toggle mechanism driven by an electric servomotor,
Seriesthe die clamping time is shortened as compared with theconventional model. (Fig. 1) The DC1300R-E features higher responsethan hydraulic die clamping and stable operation by precise position
control. As optional features of the DC1300R-E, core advanced returnand spray position intermediate stop operations are available. (Fig. 2)

Patent NewsIn addition, a high cycle is realized by simultaneous operation of theelectric die clamper and the hydraulic actuator.
32.1% reduction

Fixed diemounting surface

Unit : mm

Die clamping time (s)Ejector forward time (s)Safety hook operating time (s)3) As the number of hydraulic parts decreased, hydraulic problems
have decreased, failure time has decreased, and maintainability

Fig. 1

Cycle comparison

has improved.

Shibaura Machine Engineering Review

62

Prepared CritiqueFig. 3 Space saving

Die opening time (s)4) By adopting a large-capacity hydraulic pump as standard, theIntroductory Notespeed of hydraulic operations, such as accumulator filling, has

Table 1 DC1300R-E specification table
Specification comparison
Clamping

increased.
5) The upper 2-tie bar draw-out equipment is equipped as standard,
making it easy to change dies.

Injection6) Equipped with the newly developed large-screen TOSCAST-999
controller, the operability of the DC1300R-E has drasticallySpecial Article

improved. (Fig. 4)

Clamping force
Die plate dimensions (vertical x horizontal)
Space between tie bars (vertical x horizontal)
Tie bar diameter
Die height
Die stroke
Maximum injection force
Intensifier ratio
Injection plunger stroke
Plunger jog stroke
Injection opening position(downward from the center of the machine)
Injection speed
Plunger tip diameter (standard)Casting volume (standard insert diameter)

Technical Paper

Casting area (standard tip diameter)
Casting pressure (standard tip diameter)
EjectionEjection force
Ejector stroke
Hydraulics No. of movable cores
Movable core ports (per solenoid controlledvalve)
No. of fixed cores
Fixed core ports (per solenoid controlled valve)
Operating hydraulic pressure
Required hydraulic fluid amount
Hydraulic fluid oil tank capacity
Cooling
Die cooling water inlet connection pipe
waterdiameter
Die cooling water outlet connection pipe
Heat exchange cooling water inlet pipe
Heat exchange cooling water outlet pipe
Die cooling adjustment valve (fixed)
Die cooling adjustment valve (movable)
Plunger tip cooling water adjustment valve
Required cooling water (for heat exchange)
Required cooling water (for dies)
MachineRequired floor area (length x width)sizeTechnical Report

4

Unit
kN
mm
mm
mm
mm
mm
kN
mm
mm

DC1300R - E
13000
1895 2205
1250 1525250
700 to 1500
900
1080
1 : 2.56
950
400

DC1250CSW3
12500
1930 1800
1250 1120
250
600 to 1500
900
1080
1 : 2.56
950
400

mm

300

300

m/s
mm

0.1 to 9.0
115
7375

0.1 to 9.0
115
7375

1250 to 3215
40.4 to 104.0615
150
3/4" 21251 to 3215
40.5 to 104.0616
200
3/4" 2

3

cm

2

cm
MPa
kN
mm
Set
Set

1" 2

1" 4

Set
Set
MPa
L
L

3/4" 1
1" 2
15
2100
1880

3/4" 1
1" 2
15
2200
1900

Rc

2"

1+1/2"

Rc
Rc
Rc

L/min
L/min

3"
1+1/2"
1+1/2"
1/2" 10
1/2" 10
1/2" 150
160 to 240

3"
1"
1"
1/2" 20
1/2" 20
1/2" 150
160 to 240

mm10300 3800

11800 3500

Rc SetRc SetRc SetEffects

By implementing electric die-plate clamping, the following three
New Producteffects have been achieved.
1) Core return operation can be performed while the moving dieplate is being opened.
2) The spray operation and the moving die-plate operation can be
Fig. 4TOSCAST-999 controller

linked to shorten the spray time. *Option3) Electric servo control has made it possible to accurately approach

SeriesDocuments which are referenced by the user, such as ladder circuits,

the spray nozzle.

instruction manuals, and schematic diagrams, can be digitallydisplayed on the screen to reduce paper and improve workability.
7) Conformance to SDGs
The implementation of high-cycle technology for die casting

Patent News

machines that make products from highly recyclable aluminumalloys can improve productivity and contribute to society.

5Conclusion

The DC1300R-E is the latest model designed to improve theoperating rate and product quality.
We will continuously meet the needs of our customers by
expanding our product lineup.

3

Specifications

Prepared Critique

Table 1 shows the specifications of the DC1300R-E. The
specifications of the previous model DC1250CSW3 are also shownfor comparison. The items colored in light blue indicate improved
performance as compared to the DC1250CSW3.

63

ShibauraNAKANO
Machine Engineering
Review
Toshiaki
Metal & Plastics
Industrial Machine Company, Metal & Plastics Industrial Machine Technology Department
Shibaura Machine Engineering Review

New Product1

screw. This section is structured so excessive heat can be suppressed

Overview

by intercepting resin, applying additional shear forces, and thenAs the need for plastics becomes more diversified, the functionality

passing it through the through-hole.
HSE-48 has a motor, a control panel, and an operation panel

plastics are produced through the process of adding an inorganic

integrated in a single frame. In addition, the preliminary kneading

filler or a polymer into another kind and kneading them in an

section can be turned in the direction shown by the blue arrow in

extruder. However, if they are not sufficiently kneaded, the additiveFig. 3 so it can be compactly folded. This helps to transport thewill not be dispersed properly in the polymer. As a result, expected

machine with ease. Also, translating the preliminary kneading

functionality will not be demonstrated.

section in the direction shown by the black arrow allows us to

the length of the barrel in the high-shear section.

with HSP Technologies Inc. HSE-48 features higher shear

Through-holeTechnical Paper

High-Shear Processing Machine HSE-48 (Fig. 1) through joint studychange the feed port in the high-shear section and then to adjustSpecial Article

of extruders needs to be further extended. High-performance

To solve this challenge, Shibaura Machine has developed theIntroductory Note

Introduction of the High-Shear Processing Machine HSE-48

performance than the TEM Twin Screw Extruder Series. This reportintroduces the features of HSE-48 and example applications.
Technical Report

Fig. 2

Cross sectional view of the high-shear section

New ProductFig. 1

HSE-48
Series2

FeaturesHSE-48 consists of three sections: the preliminary kneading
section which is designed to melt resin, the high-shear section
Patent News

which is designed to apply high shear forces into resin, and themetering and pressurizing section. The Twin Screw Extruder TEM26SX is used as the preliminary kneading section. Also, a single
screw extruder with a barrel whose inside diameter is 48 mm is used

Fig. 3 When in operation (black) or being transported (blue)

Adopted as the high-shear section is a single screw extruder witha barrel whose inside diameter is 48 mm with a maximum screw
speed of 3600 min-1. As illustrated in Fig. 2, a hole is drilled throughthe side of the screw. Directly behind the through-hole is a reverse

3

Specifications

The mechanical specifications and the dimensions of HSE-48 are
as shown in the tables below.

Shibaura Machine Engineering Review

64

Prepared Critiqueas the metering and pressurizing section.

･Lowering the molecular weight of general-purpose

Table 1 Mechanical specifications
Introductory Note

Max. screw speed[min-1]

Motor power
[kW]

745

30

High-shear section

3600

132

Metering andpressurizing section

207

5.5

Preliminary kneading
sectionSpecial Article

Table 2Outer dimensions and weightH × W × H [mm](When in operation)
H × W × H [mm](When being transported)

2980×3590×1780

Weight [kg]4970

1910×3590×1780

polypropylene (PP)The production volume of a very low-viscosity resin, which is used to
manufacture meltblown nonwoven fabric, is so low it is dealt with at ahigher price than general-purpose resin. Therefore, if the molecularweight of general-purpose resin can be reduced, the raw material cost
can also be reduced. In addition, if the molecular weight of resin can be
adjusted as desired, it is expected meltblown nonwoven fabric with avariety of physical properties will be manufactured.
For this reason, we tested how much the molecular weight ofgeneral PP (melt flow ratio of 30 g/10 min) could be lowered using
HSE-48. The test was performed with a throughput of 2 kg/h and a

Technical Paper

4

Effects / Application Examples

screw speed of 3600 min-1 in the high-shear section and a barrel
temperature of 260 °C with 4 barrels. As a result, the test

Technical Report･High-density recycled CF (hereafter called RCF) compound

demonstrated the melt flow ratio (hereafter called MFR) of the PP

At first, the use of commercially available carbon fiber (hereafter

was approximately 1500 g/10 min. Typically, MFR required tocalled CF) compound was considered when the high-shear

manufacture PP meltblown nonwoven fabric is approximately 1000

processing machine was developed. However, this resulted in shorterg/10 min. Therefore, the requirement was successfully met.

New Product
Seriesfibers due to high shear forces as well as low mechanical strength.

In addition, in this study, the PP with MFR of approximately 1100

Therefore, we decided to increase the tensile rigidity of the baseg/10 min, which was produced using the high-shear processing

material rather than increase the tensile strength by exerting highmachine, was actually made into meltblown nonwoven fabrics. With

shear forces to break CF into pieces and charging more compound.

respect to the physical properties of the nonwoven fabric, the mass

Typically, a commercially available CF compound has a CF content

per unit area was 30 g/m2, and the average fiber length was 1.6 µm.

of 30 to 40wt%. But in this study, we considered charging a

The produced nonwoven fabrics looked white, became free fromcompound with a CF content of 40wt% or higher (50 to 70wt%).

discoloration, and felt flexible. Furthermore, the fibers were so

Also, low-priced RCF was adopted. As a comparison, it was discussed

densely packed no gaps were found. When the produced nonwoven

whether a CF compound with a CF content of 40wt% or over could

fabrics were observed using SEM, there were no significant variations

be charged into a twin screw extruder. But when content was 50wt%

in the fiber diameters. Also, no residual resin was found. Theseor over, scattered spots of CF were found, and CF could not be

results have proved it will be possible to perform melt blown

continuously pelletized. On the other hand, when using the high-extrusion at a lower cost while maintaining the quality of theshear processing machine, the diameter of the through-hole, theconventional products.

high-shear section were adjusted to find the optimum condition. As
Patent Newsa result, material which was stiffer than an Al alloy or as stiff as a Mg
alloy (with a CF content of 60wt%) was successfully produced. (Fig.
4) In addition, from the view of mill cost, the use of an RCF compound
may be more cost competitive than that of a commercially available

Prepared Critique

CF compound. For this reason, we will test the marketability andphysical properties (blockage of electromagnetic waves and heatSpecific strength(Tensile strength / specific gravity)^(1/3)

number of through-holes in the screw, and the screw speed in theradiation) of this material.
Specific rigidity(Bending elastic modulus / specific gravity)^(1/3)
Fig. 465

Physical properties of the high-density RCF compound

YoshioIIZUKA,
YuyaEngineering
SASAI Metal& Plastics Industrial Machine Company, Extrusion Machine Engineering Department
Shibaura
Machine
Review
Shibaura Machine Engineering Review

New Product1

Overview (Background andPurpose of Development)

Damage caused by machine tool collisions and interference canIntroductory Note

Introduction of Real-time Collision Check Function
to Prevent Machine Collisions and Interference
Features

2.1

System Configuration

lead to major damage, including the following:

Fig. 1 shows the system configuration. The Real-Time Collision

・Damage to machines, jigs, materials, and tools

Check function connects the CNC machine to an external PC via LAN・Increase in costs due to repairs and repurchases

cable to perform 3D simulations in advance. This function prevents

・Lower production efficiency due to downtime

collisions and interference by detecting interference throughsimulation using coordinates which precede the actual machine

visually checked by the operator. However, there is a lot oftool movement and stopping the operation. Since this function

dependence on the operator's sense and experience, and many

does not require a specific operation mode, it can detect tool

human errors are caused by inability to see, lack of attention, orinterference and machine interference other than cutting inother simple mistakes. Therefore, as an aid to operators, we

addition to MDI (Manual Data Input) operation and automaticdeveloped software for a Real-Time Collision Check (RTCC) function

operation, thereby reducing failures.

stops the operation.

The Collision Avoidance Software (CAS) consists of our relay
application Shiba CAS and VERICUT CAS, which is a machine collision

With this function, the following effects can be expected.

check function extracted from the NC simulation software VERICUT
provided by CGTech. At this time we are building our own CNC・Reduction of operator's work timemachine TOSNUC and Shiba CAS, so possible collisions can be

・Reduction of unnecessary cutting fluid and hydraulic oilchecked in real time.

consumption as well as electricity consumption

In order to use this function, it is necessary to prepare 3D shapemodels of machines, jigs, materials, and tools.

CNC machine

New Product・Reduction of time and cost loss due to damage

Technical Reportwhich detects collisions and interference before they occur andTechnical Paper

Currently, to prevent collisions and interference, the program isSpecial Article

2

Collision Avoidance Software (CAS)Manual OP
MDI OP
Automatic OP

SeriesStart operation
Various
instructions

ResultPresence ofinterference
Manufactured by Shibaura Machine Co., Ltd.

Patent News

Precedingcoordinates,
etc.

Manufactured by CGTech

External PC
Prepared CritiqueInterference
detected
Operation stops

Necessary to prepare 3D shape models
LAN cable(UDP communication)

Machines, jigs, materials, and tools

Fig. 1

System configuration

Shibaura Machine Engineering Review

66

2.2

Sequence Axis Motion Support

Introductory Note

3

The sequence circuit is mainly used to create the data transfer

Specifications

part for the angle indexing (AAI: Auto Attachment Index) of theTable 1 Specifications

attachment.

CNC machine

Our double column machining centers have special attachmentswith virtual axes (B-axis and C-axis) depending on the model. These

Collision Avoidance Software

two axes are controlled by the C-axis control function of the NC

TOSNUC PX200
Shiba CAS
VERICUT CAS (Version 8.2)

Special Article

CPUIntel® Xeon® processor 3.5 GHz
or moreMemory32 GB or more

the angle data is written in the data table determined by the

HDD

M2 SSD 500 GB or moresequence circuit and then sent to the CAS.

GPU

OpenGL RX4000P or more

spindle, unlike the normal servo axes. Since the data of the B- andExternal PC

C-axes under control cannot be sent directly from the NC to the CAS,

Also, if interference is identified during AAI, the machine will stop
Technical Paper* An external computer and a VERICUT CAS license need to be provided by thecustomer.

in the middle of operation. In this case, complex operations will be
required for recovery, and much time will be consumed. Therefore,4

as shown in the sequence axis operation flow in Fig. 2, the sequence

Effects and Examples

Technical Reportcircuit has been changed so as to perform the collision check before

In MDI operation and automatic operation, the operation stops

the start of the operation while this function is running and perform

one block before possible collision is detected. In manual mode,the operation only when no possible collision is detected.

operation can be stopped before collision occurs by controlling theinterference area with the machine travel speed (sensitivity can bechanged by a parameter).
Example: Fast forward 100%; stop at short of 70 mm

AAI command

Manual pulse generator (quick rotation); stop short of 30 mm
New Product

Manual pulse generator (slow rotation); stop at range short of 0.1
Real-Time Collision Check (RTCC) functionmm

The Real-Time Collision Check function can contribute to cost

Collision Avoidance Software(CAS)

reduction and energy saving by utilizing the digital twin to reduce
the time and energy consumed by repeated trial and error.

Series

Real-Time Collision Check (RTCC)
No interference
detected

5Interference
detectedConclusion

In the future, we plan to support pre-machining collision checks
Start AAI operation
Patent News

Fig. 2

Stop alarm

Sequence axis motion flow

with machine locks, collision checks for finished shapes, andautomatic input of compensation values for workpieces and tools
by on-machine measurement.

Furthermore, when the CAS starts communication with the NC at
the time of system startup, it can read the data of the servo axis, but
Prepared Critique

it cannot read the data of the tools and attachments on the spindle.
For this reason, the circuit has been created so the tool number,
attachment number, and AAI angle on the spindle are read into the
CAS when communication with the NC is established, such as when
the CAS is started or the system is restarted.

67

Shibaura AKIYAMA,
Machine Engineering
Review
Shintaro
Nana KIMURA
Machine Tools Company, Machine Tools Engineering Department
Shibaura Machine Engineering Review

New Product1

Development Objectives

for delivering more precise positioning.

3. Equipped with an ultra-precision aerostatic bearing spindle

neutral by 2050. To achieve a decarbonized society, the use of IoT

The USM-20B(H) is equipped with a high-rigidity aerostatic bearing

technologies, such as remote operations and monitoring, is essential,

spindle developed in-house. Three types of spindles are available,

but this requires the development of a communication infrastructure.

optimized for each grinding wheel diameter of 2, 3, and 4 inches.

Optical fibers used for optical communication are connected to eachother using optical connectors in repeaters and distributors. Because
misalignment in fiber connections can lead to significant transmission

4. Bed made of cast metal
The bed is made out of cast metal for providing high rigidity andTechnical Paper

loss, optical connectors are key components and high-precision

stable machining over a long period of time.

V-groove machining is used for these components.
Also, ceramic-made scintillators, power semiconductors, and5. Touch panel operation
The design minimizes the number of operation buttons, and

X-ray CT systems in medical equipment for enabling higher

microscope screen operations and selection of machining programs

precision, in automotive parts for greater automation, and inare performed from a touch panel for greater ease of operation andcommercial inkjet printers for higher resolutions. Even though these

reducing the workload of machining operators.

ceramic materials are difficult to cut, they are required to have highdue to growing demand.

Technical Reportpiezoelectric parts are used for sensors and actuators in the latest

precision, and their machining processes must be highly efficientSpecial Article

In 2020, the prime minister pledged Japan would be carbon

Introductory Note

Introduction of the USM-20B(H) High-Precision Grooving and Cutting Machine

6. Electrical discharge truing option available
The electrical discharge truing option can be used to correct
grinding wheel shaking and to optimize the wheel tip angle when

precision grooving and cutting of parts which will be key to thethe wheel is mounted. Also, with this option, grinding wheels which

above-mentioned efforts to achieve the Sustainable Development

have been worn by machining can be reshaped to enable further

Goals (SDGs) in such fields mentioned above as opticaluse to the end for minimizing waste. An example of electricalcommunications, medical care, automated driving, and printers. The

discharge truing is shown in Fig. 2.

New Product

The USM-20B(H) has been developed specifically for this high-appearance of the USM-20B(H) is shown in Fig. 1.
Series2

Features

1. V-V type dynamic pressure guideway for the workpiece
feed axis (X-axis)
Patent NewsThe V-shaped guideway surface is hand-finished by scraping andpolishing to ensure smoothness and high straightness over long
periods of time.

Prepared Critique

2. Linear motor drive and special low-waving linear guide forwheel positioning (Y-axis)
This design reduces waving motion compared to the ball screw
drive and linear guide used in conventional machines. Also, thescale resolution is 1nm, compared to 2nm for the previous model,

Fig. 1

Appearance of the USM-20B(H)Shibaura Machine Engineering Review

68Introductory Note

0.1mm
Worn grinding wheel

0.1mm

0.2mm

After electrical discharge truing

Fig. 2 V-groove bottom shape before and after electrical discharge truing
Special Article

3

Specifications
10mm

The specifications are shown in Table 1.
X-axis (Workpiecefeeding)
Y-axis (Grinding wheel
positioning)
Z-axis (Grinding wheel
height)C-axis (Workpiecerotation)
X-axisTechnical Report

Maximum feed Y-axis
rate
Z-axisMinimumcommand unit X-, Y-, and Z-axis
SpindleNew Product4

300 mm
160 mm
80 mm
Unlimited
2400 mm/min
1000 mm/min
1000 mm/min

0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6

For 2 inch grinding stone

4000 to 40000 min-1

For 3 inch grinding stone

3000 to 30000 min-1

For 4 inch grinding stone

2000 to 20000 min-1

Previous Model

1 3 5 7 9 11 13 15 17 19
Number of V-grooves
Fig. 40.00001 mm

V-grooving of low thermal expansion glass substrate

Cumulative pitch error (μm)

Technical Paper

Travel amountFig. 3Main specification values

Cumulative pitch error (μm)

Table 1

0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6

This Model

1 3 5 7 9 11 13 15 17 19
Number of V-grooves

V-grooving: Cumulative pitch error measurement results

Results and Examples

1. V-grooving on low thermal expansion glass substrates
V-grooving (0.25 mm pitch x 20 grooves for 10 sets) for optical
10mm

connectors was performed on low thermal expansion glass (100 x
Series100 x 1 mm). Fig. 3 shows the V-grooving appearance, and Fig. 4

Fig. 5Grooving on an alumina blockshows the cumulative pitch error measurement results. The
cumulative pitch error was found to be 1/2, which was significantly
better than the previous model.

5Conclusion

Looking forward, we intend to utilize the newly-developed USMPatent News

2. Deep grooving of ceramic blocks
As an example of machining on ceramic materials, grooves of 0.7
mm width, 3.7 mm pitch, and 15 mm depth were machined on analumina block (50 x 50 x 20 mm), and its appearance is shown in Fig.

Prepared Critique

5. A normal machine tool would have required multiple cuts tomachine a single 15 mm deep groove. By contrast, with this machine
tool, a 15 mm deep groove was achieved in a single cut.
Also, if the workpiece to be machined is thin, multiple workpieces
can be stacked and cut for significantly improved productivity.

69

Shibaura Machine
Review
Takaharu
TASHIRO Engineering
Machine Tools
Company, Machine Tools Engineering Department
Shibaura Machine Engineering Review

20B(H) to provide high-precision and high-efficiency machining forachieving the SDGs.

New Product1

3

Overview

Specifications

The TCmini is a microcontroller board which can be programmed

size, and cost to meet specific customer needs.
The current TC3 series has been adopted in a wide array of fields
such as air conditioners, electrolytic water systems, and milking
machines. To meet further market needs, we have developed theTC12 series, which uses the latest MCU*1 and has improved control

The TC12-02, the first model in the TC12 series, provides control
functions with higher performance while maintaining the installationand functional compatibility of the TC3-02 (previous model).

Item

TC12

TC3 (Previous model)

Processing time (1k words)

5 ms or less
24k words
16
74
7296
3978 words
Available *Option
Available *Option
Available *Option
Max. 13
12bit(Max. 24 in)
12bit(Max. 2 out)

10 ms or less
12k words←
291160
309 words
Unavailable
Unavailable
Unavailable
Max. 3
10bit(Max. 8 in)
8bit(Max. 2 out)

Program capacity
Basic
Number ofcommands
AppliedInternal Relays / Timers
Data registers
USB I/F
SD card I/F
CAN
Serial communication
Analog input
Analog output

Technical Paper

performance.

Table 1 TC12 Series Main Specifications
Special Article

in ladder logic (PLC language) and can be optimized in function,

Introductory Note

Introduction of the TCmini TC12 Series*1 MCU (Micro Controller Unit): A microprocessor for embedded
Technical Reportapplications which incorporates a wide range of peripheral
functions, such as ROM, RAM, and I/O, in a single integrated circuit.

2

TC12 Series Features
New Product1) Control performance: Half the ladder processing time of theprevious model2) Ladder program capacity: Double the capacity of the previous

Fig. 1 Appearance of the TC12-02

model
Data register capacity: 12 times the capacity of the previous
model
Series3) Enhancements to communication functions
CAN *2: Installable*3 without dedicated IC
USB I/F: Installable*3 without dedicated IC
SD card I/F: Installable*3 without dedicated IC
Serial communication: Max. 13 (10 more than previous model)

Patent News

*2 CAN (Controller Area Network): Serial communication protocol
developed by Bosch*3 Installable through customization options

Prepared Critique

Shibaura
MachineEngineering
Review
Hiroyuki OCHIAI, Koji WATANABE Control Systems Company, Control
Systems
Engineering
Department
Shibaura Machine Engineering Review

70Introductory Note

4

Results and Examples

The TC12 series not only provides higher control performance,
but also can be easily customized with a USB I/F, CAN, and othercommunication functions, which have been requested by manycustomers, for supporting their shift to smart factories. The numberof parts has also been reduced compared to the previous model,

Special Article

which was already an environmentally-friendly product.

4.1

Application Examples

Dairy machinery: Milking machines, Milk cooling systems
Kitchen equipment: Electrolytic water systems
Technical Paper

Air conditioning equipment: Bio-toilet

Technical Report

Fig. 2

Milk cooling system

Fig. 3 Electrolytic water system

New Product
SeriesPatent News
Prepared Critique71

Shibaura Machine Engineering Review

Fig. 4

Bio-toilet

My university alumni started ascience and handiwork school in the

There are now 12 members including 3 Shibaura MachineTokyo area with the aim of providing

retirees. We are funded by donations from campanies andchildren opportunities to experiencegratuity from classroom organizers. In particular, we are very

fun and interesting science throughgrateful for the support

handiworks and experiments. My

we have received fromfriends and I organized the same

Shibaura Machine sinceschool for the eastern area of Shizuoka

the establishment of ourprogram.

Technical Paper

Fumio KAMAHORA prefecture. We are providing school
Representative of KURARIKA
Shizuoka (Retired in 2008)

technologies in Japan.

Special Article

Kuramae Science Class
Fushigi-fushigi(KURARIKA)
http://kurarika.net/

Introductory Note

Inspire Children’s Interest in Science!! Activity Report from a
Retired Member

sessions in many places, such as;

elementary schools, children's homes, after-school kids clubs,
and also at Mt. Fuji children’s world (Fujisan Kodomo-no Kuni).
Our activities are based on the policy that; (1) all participants

Technical Reportexperience handiworks and experiments using materials on
hand, (2) scientific principles and laws and the mechanisms of
behavior in a specific theme should be explained in an easy-tounderstand way using a projector or demonstration device, and(3) one assistant should be assigned to each five or six children
to provide detailed guidance. It is important children make,

New Productmove, and observe things for themselves and we hope ourschool can help participants find interest in science and also
become talented people who will support future science andOoka Elementary School 4th grade "Cartesian diver class"

SeriesPatent News
Prepared Critique

Shibaura Machine Engineering Review

72Series

Shibaura Machine's History of Technology, Skills, and Products Series :No. 1 "Ultra­Precision Machine Tools"

Introductory Note

History of Ultra-Precision Machine Tools and Contributions of Shibaura
Machine to the Development of Ultra-Precision Machining Technology
This paper introduces the history of ultra­precision machine tools which and machining
technology and Shibaura Machine's role in this development.

Special Article

Machine Tools Company
Machine Tools Engineering
Department

Katsutoshi TANAKA
Technical Paper

1

Introduction

until the 1980’s, when NC­controlled ultra­precision machining
became possible that the technology was applied to consumer

Technical Report

Computers, smartphones, the Internet, and optical communi­

products such as cameras and CD players. In this way, ultra­

cations have become an integral part of our lives, making our lives

precision machining technology has become indispensable for the

faster, richer, and more convenient than we could ever haveproduction and development of the devices which support theimagined. Optical communication, PCs, flash memory, digital

information society 2)­3).

cameras, smartphones, printers, LCD monitors, and other devices

In this paper, we will introduce the historical background leading

have become common in many households as the entry and exit

to the development of ultra­precision machining technology and thepoints for information, forming a huge market. In the industrial

role Shibaura Machine has played in this development.

New Productworld, not a day goes by without the use of these devices, and withthe spread of COVID­19, the scope of their application has expanded
significantly. The magnetic disk substrates, V­groove substrates,
magnetic heads, aspheric lenses, diffraction gratings, light guideplates, optical films, and polygonal mirrors used in these devices are

2

The Process of Developing
Ultra-Precision Machining

2.1

The Process of Developing
Ultra-Precision Machining Overseas

SeriesPatent Newsultra­precision parts which can only be produced through ultra­

In the 1950's and 1960's in the U.S., research and development

precision machining, and they are the key parts which determine

on machine tools capable of ultra­precision machining by motion

the functions, performance, and popularity of the devices.1) Also,transfer was conducted by Union Carbide, LLNL, Polaroid, DuPont,

with the spread of safe and automated driving for cars, security,and others to improve the machining accuracy and productivity ofhigh­speed communication, 4K/8K, and IoT, the demand for ultra­

military­related ultra­precision parts without relying on the skill of

precision machining is expected to grow, enabling even moremachine operators. Research was conducted on aerostatic bearings

advancements.

as bearings for spindles and guideways, which are the main

Prepared Critique

Ultra­precision machining has been utilized and developed tocomponents of machine tools, and the Ultra­precision Hemispheremeet the demand for features strongly desired in these devices,

Turning Machine (Fig. 1) was developed as the first ultra­precisionnamely, more compact size, lighter weight, multi­functionality, higher

machine tool for machining of high­precision spherical surfaces.

precision, higher density, mass production, and lower costs. For

This machine used aerostatic bearings in the workpiece spindle,

example, the Schmidt corrector plate was invented in 1930 towhich holds and rotates the workpiece, and in the cutter headeliminate aberrations in aspheric lenses, but its use was limited tospindle, which swivels the diamond bit.4)­6)equipment such as astronomical telescopes and special cameras

Aerostatic bearings have been researched and developed

because no viable production technology was available. It was notsince the 1960’s, but their use was focused on high­speed

73

Shibaura Machine Engineering Review

other machine elements for ultra-precision machining werebearings could deliver high-speed rotation due to the low friction

developed for practical use, and these elements were used tocaused by the low viscosity of the air interposed between the shaft

achieve mirror-like machining of flat, cylindrical, and sphericaland bearing. However, spindles for ultra-precision machining whichsurfaces by motion transfer. However, the resolution of therequire surface roughness and form accuracy require high precision,

numerical control was 1 µm to 10 µm, and it was not possiblehigh rigidity, and low vibration, and development proceeded on

to perform ultra-precision machining of spherical and parabolic

aerostatic spindles which could satisfy these requirements. Fig. 2

surfaces (submicron form accuracy and mirror surfaces) withshows the aerostatic spindle for the work spindle used in DuPont3,

simultaneous two-axis control. To compensate for this poor

which is a larger version of DuPont1 shown in Fig. 1, and wasnumerical control resolution, an ultra-precision machine tool withdesigned for machining of spherical surfaces 400 mm in diameter.

mechanical circular interpolation, which combined linear and rotary

In this work spindle structure, hemispheres are facing each othermotion, was developed. Fig. 3 shows an ultra-precision machine

and the spherical surface supports radial and axial loads, and thetool named the Omega-X Nanometer Machine Tool developed bybearing material uses porous restrictors made of porous carbon.

Battelle Pacific Northwest Laboratories in 1978, which combines

For rotational accuracy, the measurement method is not specified,

two linear guideway axes and two swivel axes. This machine could

7)

but it is said to be 0.3 µm or less, and the rigidity is 117.6 N/µm.

Technical Paper

grinders, centrifuges, and other applications because theseSpecial Article

In the 1970’s, aerostatic spindles, aerostatic guideways, andIntroductory Noteturbomachinery, gyroscopes, grinding wheel spindles of internal

obtain a surface roughness of 1.23 nm rms and a form accuracy of
75 nm/50 mm.
Technical Report

Cutter head spindle

Cutterhead

WorkspindleNew Product25-mm width 0.4-mm
thickness endless belt

Fig. 1

Series

Machine configuration and machining accuracy(1) Runout of aerostatic spindle: 0.125 µm(2) Hemisphere form accuracy: 0.6 µm/101.6 mm(3) Surface roughness: 25 nm CLA
Ultra-Precision Hemisphere Turning
Machine (DuPont1)4)Graphite liner

Bearing
housing

Patent News

Front journal

Spindlehousing

Flexible ring
Axis

Seal

Omega-X Nanometer machine tool (1978)
Battelle Pacific Northwest Laboratories8)(Aspheric machine tool using a link configuration for the aerostatic
bearings)

Prepared CritiqueFig. 3

Rear journal
Fig. 2

Porous aerostatic spindle4)

Shibaura Machine Engineering Review

74

In the latter half of the 1970’s, high-resolution NC devices (25Introductory Note

nm resolution) were developed, and in response to requests
from DuPont and LLNL, NC-controlled ultra-precision lathes weredeveloped by Moore Special Tool and PNEUMO PRECISION, which
had amassed tremendous technological capabilities in ultraprecision machine tools. Fig. 4 shows the ultra-precision CNC lathe

Special Article(M-18AG) developed by Moore Special Tool in 1975. The machineuses the V-V roller guideway and precision feed screw technology
used in the company's jig grinders and measuring machines, aProfessional Instruments aerostatic spindle as the work spindle, anda laser interferometer for position detection. The structure is madeof cast iron and is carefully finished to the precision required forTechnical Paper

ultra-precision machining by employing highly skilled work such as
scraping and lapping.9)-12)Work spindle (aerostatic spindle)
Vacuum chuck

TurretMachine configuration and accuracy(1) Aerostatic spindle: Runout accuracy = 0.1 µm(2) Aerostatic guideway(3) Control resolution: 25 nm
Fig. 5 Ultra-precision lathe MSG-325 (1977)
PNEUMO PRECISION, INC.13)

While the purpose of the development of ultra-precision
Technical Reportmachining technology in the U.S. was to improve the accuracy
and productivity of ultra-precision parts used in military, energy,
and space development, PHILIPS pursued the development ofmagnetic disk substrates, reflectors for carbon dioxide lasers, plastic
aspheric lenses, and injection molds for plastic aspheric lenses for

New ProductIndexing tableconsumer and industrial use. This was groundbreaking researchand development which spearheaded the mass production of

X-axis(V-V roller guideway)

Z-axis(V-V roller guideway)

plastic aspheric lenses using the injection molding method15).

Series

Machine configuration and accuracy(1) Aerostatic spindle, V-V roller guideway(2) Control resolution: 25 nm
Fig. 4 Ultra-precision lathe M-18AG (1975)
Moore Special Tool 9)-10)

Fig. 5 shows the ultra-precision CNC lathe (MSG-325) developedby PNEUMO PRECISION in 1977. In this machine, the X and Z axesof the aerostatic guideway are arranged in a T-shape on a granite(a) Ultra-precision CNC lathe

surface plate, the work spindle of the aerostatic bearing is placed
Patent Newson the Z-axis, and a feedback system using a laser interferometer is
employed.13)-14)
With the advent of these machines, highly efficient andultra-precision machining of axisymmetric spherical, parabolic,Prepared Critiqueellipsoidal, and aspherical surfaces by numerical control became
possible. On the other hand, in Europe, PHILIPS of the Netherlands
developed a unique ultra-precision CNC lathe in 1980 which
employed hydrostatic bearings (linear guideway and work spindle),a hydraulic servo feed mechanism, and laser feedback (Fig. 6).

75

Shibaura Machine Engineering Review(b) Machining examples(c) Plastic lens formed byultra-precision mold
Machine configuration and accuracy(1) Hydraulic servo and laser feedback(2) Control resolution: 16 nm(3) Machining form accuracy: 0.5 µm(4) Machining surface roughness: 0.02 µmRy
Fig. 6 Ultra-precision CNC lathe COLATH (1980) PHILIPS15)

By combining a ø100 mm spherical aerostatic spindle with ourIn the 1970’s, the active research on ultra-precision machining

the flat surface machining equipment shown in Fig. 8, and studiedin Europe and the U.S. prompted Japan to conduct research on

the mirror surface machining of soft metals (aluminum alloy andthis technology as an essential cornerstone of Japan's efforts tooxygen-free copper) by fly cutting using a single-crystal diamondbuild a technological powerhouse. However, in the 1970’s, there

bit, and we obtained a flatness of 0.79 µm/ø100 mm and surface

was no budding industry in Japan which required ultra-precisionroughness of 20 nmRz.21)

Special Article

newly developed aerostatic guideway, we fabricated a prototype ofmachining, and research was limited to universities, publicresearch institutes, and corporate laboratories.16)-17) Under thesecircumstances, the author and colleagues started to work on

Aerostatic bearing

Magnetic coupling

Drive motor

Introductory Note

How Ultra-Precision Machining Was
Developed in Japan

2.2

Spherical aerostatic
bearing

ultra-precision machining as a fundamental technology fordeveloping higher accuracy and unique machine tools.

Technical Paper

2.2.1

Development of Spherical Aerostatic Spindles and Mirror
Surface Machining with Flat Surface Machining Equipment

To tackle ultra-precision machining, which requires an accuracy
two to three orders of magnitude higher than normal machining

achieve ultra-precision in the machine components, in 1977, we
acquired the technology for a spherical aerostatic spindle with an

Technical Report(a) Spindle appearance

accuracy (flatness, roundness, surface roughness, etc.), and toSpherical aerostatic bearing(axis side)

Spindle side

inherent restrictor (Fig. 7) from the Manufacturing Engineering
Research Center of Toshiba Corporation. Table 1 shows the
New Productperformance of various spherical aerostatic spindles. The runout
was measured by the Lissajous method using a capacitance-type
non-contact micro-displacement sensor.18)-20)
Table 1 Specifications of spherical aerostatic spindle

Spherical aerostatic bearing(housing side)

50

Axial
direction

50

50

50

Radialdirection

15

50

60

Axial
direction

30

60

70

Radialdirection

90

300

350

Axial
direction

180

360

400

Max.

10000

6000

5000

Runout nm

RigidityN/ μ mSupply airpressure
0.6 MPa
Allowableload capacity
N
Supply airpressure
0.6 MPa
Rotation
speed min-1

50

50

Fig. 7(b) Spindle structure
Spherical aerostatic spindle and component parts
ABS-10 (1978) 18)

Workpiece
mount

Fly cutting tool

Aerostatic
guideway

Spindle(spherical aerostatic spindle)

Fig. 8Prepared Critique

Radialdirection

100 mm 120 mm

Patent News

60 mm

SeriesSpindle diameter(spherical diameter) mm

Flat surface machining equipment (1979)
Mirror surface machining of soft metals by fly cutting21)

Shibaura Machine Engineering Review

76Introductory Note

2.2.2

Development of Metal Mirror
Machining Equipment (SPM-4)

As a part of the research commissioned in 1978 by the Industrial

Cutting
tool-side
spindleAngle indexing
table

Workpiece
Spindle holding the workpiece
Tool holder(built-in quill inching device)

Technology Agency of the Ministry of International Trade andMachining
table

Industry (MITI) under the project "Research and Developmentof Complex Production Systems Using Ultra-High Performance

Special Article

Lasers", research and development was conducted for seven years
from 1977, and the Manufacturing Engineering Research Centerof Toshiba Corporation and Toshiba Machine Co., Ltd. jointly
developed the metal mirror machining equipment (SPM-4) shownin Fig. 9(a) to supply metal mirrors machined for high-power laser
generators of the target system.21)-24)

Technical Paper(b) Equipment structure

Due to schedule constraints and the performance of NC
equipment at the time, we decided to use the spherical surface

Principle of Spherical Surface Generation
Workpiece

generating method to cut the flat, concave, and convex mirrors,
resulting in the structure shown in Fig. 9(b). The spindle for the

C-axis(workpiece axis)

cutting tools used a spherical aerostatic spindle with 100mm
Technical Report

B-axisdiameter, and the spindle which holds the workpiece used a

Convex surface
machininghydrostatic spindle due to the diameter of the faceplate and the

Workpiece

Cutteraxis

Diamondtool

C-axis(workpieceaxis)

B-axisCutteraxis

Diamond tool

Concave surface
machining(c) Principle of spherical surface generation

weight of the workpiece, and because the machining table wasFig. 9 Metal mirror machining equipment

the feed axis for plane mirror machining, a hydrostatic guideway
was used to enable smooth feeding. The rotation of each spindle
New Productand the X-axis feed drive motor were installed at locations awayfrom the machine body to reduce the effect of motor vibration.
The flatness of the machined plane mirror was 0.3 µm/ø150 mm, as
shown in Fig. 10. This metal mirror machining equipment (SPM-4) isstill in use today after 40 years, maintaining its initial performance.

SeriesPatent News

Fig. 10 Machining result from metal mirror machining
equipment(Flatness: 0.3 µm/ø150 mm) (λ=632 nm)21)-24)

Prepared Critique(a) Equipment appearance

2.2.3

Development of Polygonal Mirror
Machining Equipment

In the 1980’s, mirror machining of soft metals started, including
photoreceptor drums for copiers, diamond turning of magnetic disk
substrates (aluminum alloy) for HDDs, and fly cutting of polygonal

77

Shibaura Machine Engineering Review

mirrors for laser printer scanners, which required ultra-precision
Introductory Notemachining technology. Previously, mirror machining using
single-crystal diamond cutting tools had been called diamondcutting, and the mirror surface was intended for decorative
purposes such as rings, necklaces, watch dials, and audio knobs.
Magnetic disk substrates and polygonal mirrors, on the otherSpecial Article

hand, require geometrical tolerances for optical surfaces such as
flatness and surface roughness, and research and development(R&D) for achieving these tolerance targets was conducted on(a) Equipment appearance

ultra-precision mechanical elements such as spindles, guides, andfeed mechanisms, and on single-crystal diamond cutting tools,

Aerostatic spindle
Cuttermaterials, and evaluation methods.

Technical Paper

Indexing table
Aerostatic guideway

As a part of this R&D, applications for polygonal mirrors (rotating

Saddlepolygonal mirrors) for laser printer scanners were studied based on

Bedthe results of mirror machining by fly cutting using the flat surface
machining equipment shown in Fig. 8. Previously, polygonal
mirrors had been used as angle standards to measure theTechnical Report

indexing accuracy of rotary tables and other equipment and were
manufactured by optically polishing glass. Consequently, the large(b) Equipment structure

weight and high cost of glass was not conducive for use in scanners
which required mass production.25)-29)

Drive table

The typical form and accuracy of a polygonal mirror used in

Aerostatic joint

Main table

Air bearing

Gear box
New ProductWirea scanner for a laser printer is shown in Fig. 11. These polygonal-1

mirrors are used at high rotational speeds (7000 to 40000 min )and require mass production. To meet these requirements, thepolygonal mirror machining equipment shown in Fig. 12(a) and(b) was developed. The system uses a 100mm diameter sphericalaerostatic spindle as the cutter axis and uses an aerostatic table as(c) Structure of aerostatic bearing table using aerostatic joints
Fig. 12 Polygonal mirror machining equipment

Seriesthe feed axis. As shown in Fig. 12 (c), the aerostatic table is divided

WeightTrapezoidal screw

into a drive table with a fixed female screw and a main table, andthe structure is designed so only the force in the feed direction actson the main table through a non-contacting aerostatic joint.

Angular indexing is performed by an indexing table using acurvic coupling with 360 teeth. The workpiece holder is presetwith 10 to 20 workpieces stacked on top of each other, and thisworkpiece holder is mounted on the indexing table and machined
at a feed rate of 50 to 200 mm/min30).

Patent News

Adjacent face tangle error 3” to 30”

The cutter holder has four cutting edges for roughing (two),arranged in the radial and axial directions at different depths of cut
and feed rates, making it possible to complete the finishing process
in a single cut for a finishing allowance of about 0.1 mm, making
this method suitable for mass production (Fig. 13). The cutter holder
λ/4 to λ/8

Fig. 11

Example of form and required
accuracy for polygonal mirror

was used to fly-cut the polygonal mirror, and a surface roughness

Shibaura Machine Engineering Review

78

Prepared Critique

45°±3” to 2’

medium finishing, and finishing, and the four cutting edges are

of 5 nmRz was obtained (Fig. 14). The measuring instrument was
Introductory Notethe Taylor Hobson Talystep, an ultra-precision surface roughness
and film thickness device which employs a probe.
Cutter holder

Workpiece
Special Article(a) Equipment appearance
Indexing table

Indexing axis

Technical Paper

Fig. 13

Workpiece

Cutter holder and workpiece

Technical Report

Cutter holder
Fig. 15(b) Cutter holder and workpiece
Polygonal mirror machining equipment UFG-80C(P)designed with more compact size, higher efficiency, andmore stability

2.2.4 Development of Disc Lathe
New ProductFig. 14 Surface roughness of polygonal mirror machined by fly cutting

As the recording media for computers shifted from magnetic

Since the development of the polygonal mirror machining

tape to magnetic disks, we developed an ultra-precision front lathe

equipment shown in Fig. 12, we have been able to meet the(Fig. 16) in 1982 for mirror-finishing aluminum alloy disks used as

demand for polygonal mirrors, and with the advancements in ultra-

material for magnetic disks.33)

SeriesPatent News

precision technology, we have developed the polygonal mirror

Magnetic disk substrates required an accuracy of 25 nmRa

machining equipment shown in Fig. 15, which incorporates a newfor surface roughness, a runout of 0.051 mm at 3600 min -1, andstructure and mechanism to achieve more stability, more compact

an acceleration of 38.1 m/sec2 at that runout (the current ANSI

size, and higher efficiency at a lower cost. The aerostatic guideway

standard in 1985). Discs had to be machined with high efficiency

is a special V-V sliding guideway designed for accuracy and stability,

to have outer diameters of 14 inches, 8 inches, 5 1/4 inches, andand the infeed axis, which used to be a V-V sliding guideway, isa thickness of 1.905 mm±0.025 mm. 31)-33) Even so, most of thea linear guide for enabling improved positioning accuracy. The

specifications for machine tools were 5 1/4 inches or less in outerindexing axis, which is the horizontal axis, has a bearing structure

diameter due to the demand for increased recording density andand supports the workpiece holder at the center, enabling theminiaturization. Because of the required machining accuracy,

number of stacked workpieces to be increased. A high-resolution

aerostatic bearings were used for the spindle, and magnetic

encoder is used for detection of the indexing angle.

couplings were used to drive the spindle and to block motor

Prepared Critique

The market for laser printers is still just under 40 million units per

vibration. The disc substrate was held by a vacuum chuck, andyear, with sales of almost 5 trillion yen, accounting for over 80%

urethane rubber was bonded to the surface of the chuck faceplateof all printers in terms of sales. Looking forward, demand is also

to reduce scratches and inaccuracies (micro-waviness) caused

expected for polygonal mirrors in scanners for automated and safeby trapped dust and chips, but the soft urethane rubber made it

driving of automobiles.

extremely difficult to cut with high accuracy. Aerostatic bearings

79

Shibaura Machine Engineering Review

available for these machining processes, and performance waswere used for the feed mechanism to prevent disturbance to theunsatisfactory, so a "dicer" for dicing silicon wafers was used.
The machining of magnetic heads involves cutting, grooving,table.

and surface grinding of the single-crystal ferrite material. Thin,

was performed using a single-crystal diamond flat bit with a cutting

all-round, and cup-shaped ultra-fine diamond grinding wheels areedge width of 1.5 mm to 2.5 mm. The machining time for a 5 1/4

used in this high value-added machining process, during whichinch substrate was 20 to 30 seconds, and automatic attachment,

95% of the material is ground into chips. Development was carried

removal, and transfer of the mirror-finished disk substrate,out with the expectation the resulting solution would become

thickness measurement, and complete chip removal were requireda high value-added product because an ultra-precision surface

for enabling production by unmanned operation.

grinder "slicer" with high rigidity and high accuracy would generatehigher demand than a "dicer" for meeting the increasing demand

replaced by less costly lapping in the late 1980’s and had a short life

for magnetic heads and for machining magnetic heads (heads forof less than ten years.

magnetic disks and 8 mm video heads) with even higher accuracy.
The USM-300A(NC) ultra-precision slicer we developed earned areputation for high accuracy and performance, but its price andTechnical Paper

This diamond turning of magnetic disk substrates was eventually

Special Article

Mass production was the basis of parts machining, and cutting

Introductory Note

were used for the guideways, and aerostatic joints and friction drive

equipment size (four times larger than a dicer) prevented its mass
adoption.

for a head, it examines how to fill the order using its existing
equipment capacity, work system, and outsourcing, and if it still

Technical Report

When a magnetic head manufacturer receives an order inquiry

cannot fill the order, the manufacturer will then consider installing
new equipment. The quality and delivery time of the equipment

determined, the order is placed with a machine manufacturer
which can satisfy these requirements to produce the head.

(a) Equipment appearance

New Productare absolute requirements, and when an order for a head is

However, because the recording density of magnetic disks is
Vacuum chuck
faceplateconstantly growing, equipment which was recently installed cannot
Workpiece auto-loader

be reliably used for the next head order inquiry, and further new

we developed the CNC ultra-precision slicer USM-200A(NC) in 1984

Seriesequipment will need to be considered. Under these circumstances,

Workpiece
spindle(sphericalaerostatic
spindle)(Fig. 17(a) and 17(b)) to meet user requirements.
For the grinding of ferrite, which is a hard and brittle material, acylindrical aerostatic spindle with a radial diameter of 60 mm wasTool holder(b) Appearance of automation mechanism
Fig. 16 Automated disc lathe33)

accuracy, and low vibration. Measures were taken to obtain

Patent News

used for the grinding wheel spindle to achieve high speed, highWorkpiece

thermal stability, such as designing a restrictor with low heatgeneration to reduce the heat generated at high-speed rotation

2.2.5 Development of Ultra-Precision Slicer

spindle, and controlling the temperature with a constant supply of

From around 1980, the demand for video heads increased, and awarm water. Fig. 18 shows an example of an aerostatic spindle withhigh-precision surface grinder was required for the fine machining

measures for preventing thermal deformation. In addition to theof single-crystal ferrite. However, no suitable machine tool wasuse of low thermal expansion materials and water-cooling of the

Shibaura Machine Engineering Review

80Prepared Critique(12000 min -1), using a low thermal expansion material for themotor, the housing mounting position was modified. This was done

Cooling
jacketIntroductory Noteby proportionally dividing the distance A from the spindle end to

Coolingwater

Balancering

the reference surface and the distance B from the reference surface
to the housing mounting surface by the inverse ratio of the linear
expansion coefficient of the material used. When the temperature
is stable, the reference surface moves backward with respect to theSpecial Article

housing mounting surface by B × Linear expansion coefficient of

Spindle(inverter)

the housing material, and the spindle moves forward by A × Linear
expansion coefficient of the spindle material, resulting in zero

Housing

Thrustbearing

Fig. 18 Structure and thermal deformation prevention measures for cylindricalaerostatic spindle for ultra-precision slicer 35)

elongation at the axis end with respect to the mounting surface.
The spindle is made of Invar (coefficient of linear expansion: 16-6

× 10 / °C), and the housing is made of stainless steel (SUS420J2,
Technical Paper-6coefficient of linear expansion: 9.7 × 10 / °C).

The X-axis (table) guideway for creep grinding is a V-V sliding
guideway, which provides high precision, high rigidity, and smooth
motion. The straightness of the table motion of the V-V sliding
guideway, which has a carefully scraped finish (Fig. 19), is less than
0.3 µm/400 mm, contributing to high precision. The Y and Z axes
are positioning axes and are linear guides with a small coefficientof friction and a scale feedback system with a command unit of 0.1

Technical Reportµm.
With the demand for higher productivity in machine tool
manufacturing and the decline in the skills of scraping andlapping, which is demanding and inefficient work, it was a great
achievement to successfully improve, transfer, and maintain

New Productthe skills which are considered essential in the manufacture of(a) Equipment appearance

ultra-precision machine tools.

SeriesPatent News(b) Equipment structure
Machine structure(1) X-axis: V-V sliding guideway(2) Grinding wheel spindle: Cylindrical aerostatic spindle
Fig. 17

Fig. 19

Scraping work

Ultra-precision slicer USM-200A(NC) 34)

Prepared Critique

The USM-200A(NC) ultra-precision slicer earned a high reputation
among many magnetic head manufacturers, and four models
with simplified functions were added to the series, resulting in thedelivery of about 1,200 units over a six-year period from 1984 to
1990. The success of the ultra-precision slicer contributed to making

81

Shibaura Machine Engineering Review

Japan the world's leading production base for magnetic heads,

high-precision guideway, feedback scales, and NC control.

Machine (now Shibaura Machine) became the driving force behind

aerostatic spindles are more resistant to seizure due to overload

its expansion within the company from a section to a department,

and other causes, and measures for preventing heat generationand to a business unit. However, as magnetic heads became

enable a spindle with a radial diameter of 60 mm to achieve a

miniaturized as recording densities increased, thin-film heads using

rotational speed of 17000 min-1 and a rigidity of 35 N/µm in thewafer processes were developed and became widespread due toradial direction (load capacity: 300 N) and 60 N/µm in the axial

their suitability for process shortening, miniaturization, and higher

direction (load capacity: 600 N). Previously, aerostatic spindles haddensity. Ferrite heads were barely able to compete with thin-film

been used for ultra-precision machining, such as mirror surface

heads through their efforts to improve performance, but once a

machining, where the load is small, but we thought if the abovecertain line was crossed, they instantly lost the market to thin-film

performance could be obtained, they could also be used for small-heads.

diameter end milling. And so, a cylindrical aerostatic spindle withslicers dropped to 1/10, new equipment could no longer bea diameter of 60 mm was mounted on the milling machine of theequipment for cutting tests (Fig. 20).

expected, and the era of ultra-precision slicers for magnetic heads
came to an end in the early 1990’s. Subsequently, although theTechnical Paper

With the shift to thin-film heads, the number of ultra-precision

Special Article

By using carbon as their bearing material, the cylindrical

Introductory Noteand the recognition of ultra-precision machining within Toshiba

ø60mm cylindricalaerostatic spindle

number of ultra-precision slicers is not expected to be as large

Technical Report

as it once was for magnetic heads, demand is expected to growfor grooving of inkjet heads, cutting of SiC substrates for power
semiconductors, cutting of optical materials, and grooving ofV-groove substrates for 5G.

Performance Improvements for Aerostatic
Spindles and Development of High-Speed
Ultra-Precision Machining Centers

New Product2.2.6

We have manufactured various types and large quantities ofaerostatic spindles by producing ultra-precision slicers and othermagnetic head-related grinders. This experience has enabled us to
improve the performance of the aerostatic spindles through higher

range of applications. Let us present an interesting application

Collet chuckhere.
By varying the supply air pressure before and after the opposing

Seriesspeeds, higher accuracy, and toughness, and has expanded theirWorkpiece
Fig. 20

End mill machining test using aerostatic spindle

thrust bearings of a cylindrical aerostatic spindle, the spindle

clearance (bearing clearance is 16 µm per side) during rotation

which in turn enables the selection of a cutting speed suitable forand positioned with an accuracy of 0.1 µm. For the purpose of

the tool material, enables faster feed rates, longer tool life due tosimplifying the mechanism in a horizontal spindle surface grinder

less vibration, improved machined surface roughness due to lesswhich uses a cup grinding wheel, a high-speed retract mechanism

center runout, more stable feed rate per cutting edge due to less

was developed which does not have a controllable feed axis, but

center runout, and longer tool life. Also, the temperature rise of theallows the grinding wheel to be released by 3 to 5 µm and theworkpiece is minimized due to adequate chip evacuation and thewheel to be positioned in the forward position by simply switching

carrying away of the cutting heat by the chips. Using this millinga solenoid valve. This mechanism has eliminated the need for amachine, grooving of workpiece material FC200 was carried out

Shibaura Machine Engineering Review

82

Prepared Critique

The use of aerostatic spindles enables high-speed rotation,

Patent Newscan be moved back and forth within the range of the bearing

using an end mill with a diameter of 6 mm (two flutes, material
Introductory Note

grade ME-10) under the machining conditions of a rotational speed

Z-axis (head)of 12000 min-1, a feed rate of 493 mm/min (maximum speed of themilling machine used), and a depth of cut of 5 mm. As a result, thecutting force was 114 N in the X-direction (feed direction), 98 N in
the Y-direction (perpendicular to the feed direction), and 28 N in

ø60mm
cylindricalaerostatic spindle

Special Article

the Z-direction, which was well within the capacity of the 60 mm
diameter cylindrical aerostatic spindle. Because the center runout
is small, the variation of the cutting force in the X-axis direction issmall and stable (Fig. 21).

Technical Paper

Y-direction

X-axis (table)

Technical Report

Y-axis (saddle)
Z-direction

X-direction

Fig. 22

High-speed machine tool with aerostatic spindle
JRV-40S was delivered to Industrial ResearchInstitute of NIIGATA Prefecture

Once Mr. TAKEOKA proposed his new machining method, Toshiba
Machine worked to develop a high-speed machine tool product

New Productspecialized in aerostatic spindles and further increased the spindle
speed to 60000 min-1 at a radial diameter of 40 mm and to 80000

SeriesFig. 21 Cutting force in X, Y, and Z directions for end mill machining using
aerostatic spindle

min -1 at a radial diameter of 21 mm. The market did not easily

Based on these results, a cylindrical aerostatic spindle with

LED-related optical components was born. Therefore, in 2008,a diameter of 60 mm was mounted on the spindle of a verticalthe machine was redesigned as an ultra-precision machining

machining center (JRV-40S), which was exhibited at JIMTOF incenter with linear motor drive for all linear axes to improve1992 (Fig. 22). At that time, the die and mold industry was looking

machining accuracy and mirror surface quality, an ATC, and various

for a way to directly machine shapes by high-speed cutting

attachments for diversification.

grow due to a lack of compatible applications, but demand forPatent News
Prepared Critique(direct engraving) instead of EDM-based machining processes for

In recent years, the halogen lamps and other light sources in

reducing costs and shortening lead times. Mr. Etsuo TAKEOKA of

automobile headlights have been replaced by LEDs, and lenses

the Industrial Research Institute of NIIGATA Prefecture installed

and reflectors have become plastic components. As a result, molds

this machine, which was exhibited at JIMTOF, and studied theare required to have high accuracy (form accuracy and surface

effectiveness of direct engraving using a small-diameter end millroughness), complex shapes, and large sizes. Because the number

for hard steel such as forging dies (reducing machining time,of parts which cannot be polished as before has increased, we

simplifying NC machining data, skipping the polishing process,developed the ultra-precision machining center with 5-axis control

and improving machining accuracy). He received his degree for his

shown in Fig. 23. Fig. 24 shows an automobile lamp reflector moldthesis, "A Study on End Milling of High-Hardness Materials by High-machined by this machining center.

Speed Aerostatic Spindles."

83

36)

Shibaura Machine Engineering Review

machine tool which could outperform the M-18AG and MSG-325.

T-shaped aerostatic bearing table on a cast iron base, a turret on
the X-axis, a spherical aerostatic spindle on the Z-axis, and a table
feed mechanism with laser feedback using a ball screw and servo

Introductory Note

The machine configuration is based on the MSG-325 with amotor by INLAND. Because it was not possible to outperform thewe decided to develop what is now called the personal computer(PC) NC unit. However, in 1984, PCs were not reliable, and it was notpossible to put a spherical aerostatic spindle weighing nearly 100

Special Article

M-18AG and MSG-325 so long as we used Allen Bradley's controller,

kg on a table with aerostatic bearings, and so this first development
model was almost never used and had to be scrapped.
Then, based on the failure of the first development model, we
selected a high-stability PC with the same machine configurationand enlarged the aerostatic guideway to better withstand the load,

Technical Paper

Fig. 23 Ultra-precision machining center UVM-700E(5AD)
Simultaneous 5-axis control

and proceeded with development of the second model. This madethe machine bigger, but we were able to achieve cutting. Even so,

the aerostatic guideway, fluctuation of the laser beam running in
the air, and other factors. We tried test machining at the customer's

Technical Report

the machining surface was unstable due to the lack of rigidity insite, but could not obtain satisfactory results, and so this ended in
failure like the first machine (Fig. 25).
New ProductFig. 24 Lamp reflector mold for automobile

2.2.7

Development of Ultra-Precision Aspheric
Machine Tools and Opening New Markets(1) Background to the development of the ultra-precision aspheric
Seriesmachine tool
As mentioned before, NC-controlled ultra-precision lathes weredeveloped in Europe and the U.S. between 1975 and 1980, andI was impressed when I saw Moore Special Tool's M-18AG and

Fig. 25 Second prototype of ultra-precision CNC lathe UAG-150A(NC)in 1980. At that time, there was already a demand for CD pickup

controller, including bugs, the instability of using a laser length

lenses in Japan, and the first ultra-precision CNC lathe (MSG-325)

measuring device as a feedback scale in a factory environment,

was introduced into an optical manufacturer in 1982. With thisthe low rigidity of the X- and Z-axis moving components using

background and the fact Toshiba Machine was already able toaerostatic guideways (especially for unbalanced loads), and themachine flat and spherical optical mirror surfaces with its metal

resulting scoring on the guideway surface.

mirror and polygonal mirror machining equipment, it was only
natural we would want to expand into the machining of spherical,(2) Development of limited V-V roller guideway

parabolic, and aspherical surfaces by controlling two axes, and in

After the failure of the machine using the aerostatic guideway,

1984, we began the development of an ultra-precision aspheric

we began to study the best guideway for an ultra-precision

Shibaura Machine Engineering Review

84

Prepared Critique

The main reasons for this failure were the instability of the
Patent NewsPNEUMO PRECISION's MSG-325 at the Chicago Machine Tool Show

machine tool. At the time, Toshiba Machine had an extensive

Table

Retainer

Introductory Note

track record of using hydrostatic bearings in large machine tools,
and so we used them in the linear guideways of a large ultra-

V-V
guideway

precision machine tool with a moving weight of 4 tons. However,the pressurized oil became a source of heat, and thermal stability
in the ultra-precision range could not be obtained even whenNeedle (roller)

Special Article

the oil temperature was controlled to ±0.01°C. This is because
oil pressurized at 0.3 to 0.5 MPa is supplied to the guideway

Bedsurface as pocket pressure, and heat is generated by the pumping
action when it is opened to atmospheric pressure, and so the oil

Fig. 26

Experimental apparatus for limited V-V roller guideway

temperature at the outlet is measured and pressurized oil at alower temperature than the machine body temperature is supplied,(3) New concept for ultra-precision aspheric machine tools

Technical Paper

resulting in a thermal imbalance. For these reasons, we thought

In Japan, the demand for aspheric lenses in CDs and camerasthat a hydrostatic bearing was inappropriate as a linear guideway

increased, and Moore Special Tool's M-18AG and PNEUMO

for an ultra-precision aspheric machine tool.

PRECISION's MSG-325 were imported to meet this demand.

Technical Report
New Product

Although the ultra-precision, high-rigidity, compact, and low-

However, among domestic machine tool manufacturers, incost features of the V-V sliding guideway had been proven in the

1985, Toyoda Machine Works (now JTEKT Corporation) released

ultra-precision slicer, the sliding bearing had a large coefficient of

a CNC ultra-precision aspheric surface machine tool (AHN10),

friction of 0.2 to 0.3, making it impossible to handle fine positioning

and Nachi-Fujikoshi released an ultra-precision aspheric surface

and low-speed movement due to the stick-slip problem. Moore

machine tool (ASP-10). Later, in 1991, Toshiba Machine enhanced

Special Tool's M-18AG had a V-V guideway with aligned rollers forthe peripheral equipment such as a limited V-V roller guideway,

eliminating this problem through rolling friction. We examineda cylindrical aerostatic spindle driven by a synchronous motor,

this guideway system, made some improvements, and evaluateda controller (FANUC FS15-MA, control resolution: 10 nm), and an

the coefficient of friction, rigidity, motion accuracy, and micro-

optical scale (HEIDENHAIN LIP401, minimum gradation: 10 nm)

waviness using the experimental apparatus shown in Fig. 26, inand promoted the development of an ultra-precision aspheric

which a needle is inserted between the cast iron bed and table.

machining tool with a new concept utilizing the experience of our

The results showed the coefficient of friction was 0.003 to 0.005,

two failed attempts.

Seriesand the rigidity was 10 to 20 times higher than that of aerostatic

From early on, Toshiba Machine had been researching glass

bearings. The guideway surface was finished by scraping, and thelens production methods using the heat press method and had

unevenness of the scraping caused micro-waviness of 0.3 to 0.5 µm,

developed a high-accuracy optical glass element molding system

but we found the micro-waviness could be reduced by using handwhich enabled rapid and uniform heating using infrared lamps,

lapping to remove the unevenness from the scraping.

precise control of heating and cooling temperatures, and control ofPatent News
Prepared Critique

In addition, we reduced the surface pressure by arranging many

mold position and press force. Unlike resin molding, the pressing

small-diameter needles at a pitch of 5.6 mm as guideways for thetemperature of glass is as high as 400°C to 750°C. Therefore, heat-ultra-precision machine tool with expectations for positive effects

resistant cemented carbide and ceramics were used as moldin averaging and longer life. To simplify the structure and increasematerials, and machining had to rely on grinding. In addition, as

the rigidity, the V-V guideway surface was installed directly on thedigital cameras and camera phones gained higher performancecast iron bed and table. Although the material was cast iron, coldfeatures, the number of glass aspheric lenses was also expected

metal was applied to the guideway surface area during casting, andto increase. Against this backdrop, we began development of anso the hardness of the guideway surface was formed as Hv280.

ultra-precision aspheric grinder (ULG-100A) based on the concept
of ultra-precision, high rigidity, high stability, compact size, and low
cost, with a focus on grinding functions.

85

Shibaura Machine Engineering Review

1/2 to 1/3 the price of existing machines and incorporated theinclude errors in relation to the commands in the machining

following features: (1) Simplified structure, (2) Utilized establishedprogram, and these errors were caused by machining conditions,

elemental technologies such as spindles and guideways, (3)workpiece centering, tool wear, tool shape, deformation due

Employed high-resolution scale feedback system, (4) Eliminatedto machining force, and thermal deformation. For this reason,

hydraulic units by employing a limited V-V roller guideway, and (5)we adopted a method of measuring the machining results andReduced installation area with a compact design.

program which corrects the error between the machining results

experience with failures and improved technological capabilities,

and the command value to converge to the target value. Because

and so, after less than a year of development, the first model

this compensation method assumes the machine, tools, and(ULG-100A(H)) (Fig. 27) with two-axis control (X and Z axes) was

environment do not change between the pre-machining andcompleted in June 1992 and delivered to the lens manufacturer

the compensation processes, we decided to use a highly stable

who had been waiting for its completion. After 28 years, thislimited V-V roller guideway, a high-resolution glass scale, andmachine is still in use at universities for research on ultra-precision

full temperature control at each location. (Incidentally, Toshibamachining.

for the feedback scale of an ultra-precision aspheric machine tool,of the bed for compactness and greater ease of operation. The

and other companies have since adopted high-resolution glass

control panel is a heat source and a 50 mm gap was provided toscales for their feedback systems.) For this reason, the machine wasavoid heat conduction, but it was found the bed was deformed

designed with a highly rigid integrated-structure cast iron bed withby radiant heat when the machine was used for long periods of

X and Z guideways arranged in a T-shape to eliminate overhangs

time, and so unfortunately, the design was changed to a separate

caused by movement and reduce the effect of deflection caused bycontrol panel. From our experience with the ultra-precision slicer,

moving loads. The reason for the emphasis on making the machine

we realized humbly incorporating user requests and opinions

compact is so the machine can be configured as small as possible

would lead to the development of machines and new models

since most workpieces were 100 mm or less in diameter, and highwhich would sell well, and so we gradually increased the number ofrigidity can be easily obtained with compact machine sizes. It alsodelivered units while adding improvements.37)

New ProductAs shown in Fig. 27, the control panel is integrated into the backTechnical Report

Machine was the first company to use a high-resolution glass scaleTechnical Paper

The development phase proceeded smoothly due to our past

Special Article

repeating the re-machining several times with a compensation

Introductory Note

In ultra-precision machining of lens molds, the machining results

has the advantage of reducing the volume of the thermostaticchamber, leading to more precise temperature control and higher
energy savings. In addition, this machine aimed to reduce the size
Seriesof the table and other moving components by using limited V-Vroller guideways with high rigidity and load capacity.
Expensive ultra-precision CNC lathes were imported from the
U.S. for the purpose of making aspheric lenses which would satisfy
the performance requirements during the development stage ofPatent News

cameras, CDs, and DVDs. The applications for aspherical lenses
were consumer cameras, camera phones (which did not exist
in the 1980’s, but developed into a phenomenal market in later
years when it became possible to manufacture compact, high-(a) Equipment appearance(b) Equipment structure
Fig. 27 First model of ultra-precision aspheric grinder ULG-100A(H)(4) Training and supporting advanced researchers through ultraprecision machining and industry-academia collaboration

for which prices were expected to decline as product volumes

In the 1990’s, the machining equipment, machining technology,

increased, and it was only natural the molds and machining

software, elemental technology, control technology, and mea-

equipment used to manufacture aspheric lenses would also needsurement related to ultra-precision aspheric machining were

to be greatly reduced in cost. The new machine was designed to be

searching for direction, and I believe research in industry-academia

Shibaura Machine Engineering Review

86

Prepared Critique

performance, low-cost lens units), CDs, DVDs, and other products

collaboration contributed greatly to subsequent development.
Introductory Note

In November 1992, Dr. Toshiro HIGUCHI asked us to develop

Grinding spindle(aerostatic bearing)Y‑axis (limited V‑V roller guideway)

an ultra‑precision aspheric machine tool with simultaneous
4‑axis control, as shown in Fig. 28, as a tool for his research on
ultra‑precision machining at the Kanagawa Academy of Scienceand Technology (KAST). We used the same X and Z axes as those of
the ultra‑precision aspheric grinder provided the work spindle on

Special Article

the Z‑axis with a built‑in FANUC servomotor with C‑axis function,and located the Y‑axis on the X‑axis. The limited V‑V roller guideway
is a mechanism where the table and the weight on the table applies

Workpiece spindle(C‑axis, aerostatic
bearing)a preload to the guideway surface, but this cannot be applied to

X‑axis(limited V‑V roller guideway)

vertical guideways. As a last‑ditch effort, we adopted a structure
Technical Paper

where the moving component was clamped from both sides andZ‑axis(limited V‑V roller guideway)mechanically preloaded as shown in Fig. 29. However, because of
the wide‑guide structure, orientation changes occurred during

Fig. 28 Ultra‑precision aspheric machine tool with
4‑Axis control ULG‑100A(H3) delivered to
KASTmovement, and we could not obtain the same motion accuracy as
the X and Z‑axes. Later, this was developed into a method whereTechnical Report

the V‑V roller guideway was situated for the Y‑axis in the same way

NeedleMoving component

as for the X‑ and Z‑axis and the reaction force of the aerostatic
bearing, or the attractive force of the magnet of the linear motor,
Preloadwas used to apply a preload. Mitutoyo Corporation developed a
feedback scale with a resolution of 1 nm, and we decided to use
New Productthis scale. Dr. HIGUCHI told us, "We are developing a machine which

Movingcomponent

has never existed before, so let's incorporate new mechanisms andelemental technologies even if it means taking risks."
Dr. Yutaka YAMAGATA of RIKEN has contributed to the

Needledevelopment of ultra‑precision machining by using this machineto create special free‑form surfaces and developing software.
SeriesDr. Toshimichi MORIWAKI and Dr. Eiichi SHAMOTO of Kobe
University (as of 2021, Nagoya University) were involved in ultra‑

Preload (aerostatic bearing)
Fig. 29

Change in structure of Y‑axis guideway surface

Patent News
Prepared Critiqueprecision machining since early on, and we delivered ultra‑precision

Dr. Katsuo SHOJI and Dr. Tsunemoto KURIYAKAWA of Tohoku

aspheric grinders, mirror machining equipment, and aerostatic

University introduced an ultra‑precision aspheric grinder andspindles for their research. Dr. SHAMOTO continued his researchclarified the relationship between ultra‑precision machining of new

on ultra‑precision cutting of hardened steel with single‑crystal

workpiece materials, machine behavior, and machining accuracy.

diamond tools using the elliptical vibration cutting method andThey also proposed the parallel grinding method as a new grinding

expanded the application of ultra‑precision machining as a new

method, and we were able to build a prototype of a specializedmachining method for use in lens mold machining and automotive

machine for this process (Fig. 30). Dr. Gao WEI of Tohoku University

lighting‑related mold machining. Later, Dr. Hirofumi SUZUKI

has been implementing the use of ultra‑precision machining(now at Chubu University) joined him and pioneered numerous

technology in the field of measurement, such as the creation

applications for ultra‑precision machining and has trained manyof large‑area three‑dimensional micropatterns on edge and38)

engineers and researchers.

cylindrical surfaces using an ultra‑precision aspheric machine tooland conducting research and development on a surface encoder

87

Shibaura Machine Engineering Review

for position and orientation detection with five degrees of freedom.
Introductory Note

In addition, we have delivered more than a dozen ultra-precisionaspheric machine tools and aerostatic spindles to universities andresearch institutes such as the University of Hyogo, Kumamoto
University, Hiroshima University, Toyo University, RIKEN, and the
Fukuoka Institute of Technology. And over the past twenty years,
several research results using Toshiba Machine's ultra-precision

Special Article

aspheric machine tools have been presented in the ultra-precision
machining sessions at scholarly conferences of the Japan Society of
Mechanical Engineers, the Japan Society for Precision Engineering,and the Japan Society for Abrasive Technology. I believe the(a) Equipment appearance

research at these universities has contributed to the application

Technical Paperof ultra-precision machining technology to optical components,
which has developed significantly since the late 1990s.

Workpiece spindle(aerostatic bearing)

Grinding spindle
Technical Report

X-axis(limited V-V roller guideway)

Fig. 30 Ultra-precision aspheric machine tool for parallel
grinding of aspheric lens molds

New ProductZ-axis(limited V-V roller guideway)(5) Evolving ultra-precision aspheric machine tools by adding newelemental technologies
Since the first machine in 1992, the variations of ultra-precision
machine tools have expanded to nine models in the range of
2-axis control to 5-axis control in response to user demands for

Series(b) Equipment structure
Machine configuration and accuracy(1) X, Y, and Z-axis: Limited V-V roller guideway(2) X, Y, and Z-axis drive: Cored linear motor(3) C and B-axis: Aerostatic bearing(4) C and B-axis drive: Synchronous motor(5) Control resolution (X, Y, and Z-axis): 1 nm
Fig. 31 Ultra-precision aspheric machine tool
ULG-100D(5A)
5-axis (X, Y, Z, C, B)

higher accuracy, changes in workpieces, and lower prices, and thetechnical improvements made during this period will be described.
Fig. 31 shows the ULG-100D(5A), a 5-axis controlled ultraPatent News

precision aspheric machine tool, which is the top-of-the-line
machine among ultra-precision aspheric machine tools. In
addition, the ULC-100F(S), an ultra-precision aspheric machine tool
specialized for cutting, has made it possible to obtain a smooth

Prepared Critiquemachined surface by reducing the instruction unit of the programfrom the usual 1 nm to 0.1 nm. Fig. 32 shows the excellent tracking
performance of this machine at a step feed of 0.5 nm.

Fig. 32

Tracking performance of ULC-100F(S) at step feed of 0.5 nm

Shibaura Machine Engineering Review

88

① Evolved limited V-V roller guideway

distorted pull line caused by the vibration generated by a large

Introductory Note
Special Article
Technical Paper
Technical Report

In the grinding process using a grinding wheel with a large

amount of air flowing through the pipe, and as shown in Fig. 34,

number of random cutting edges, the surface roughness is limited

this adversely affects the quality of the machined surface. For thisto about 20 to 30 nmRz, and no effect is observed for the micro-

reason, we developed a porous restrictor type aerostatic spindle

waviness caused by the limited V-V roller guideway. However,which can narrow the bearing clearance, reduce the air flow rate,

Toshiba Machine's product was inferior to competing hydrostaticand increase the bearing rigidity (Fig. 35). Porous metal is usedbearing machines in cutting with single-crystal diamond tools,

for the porous restrictor, and the surface is clogged with solid

and users evaluated Toshiba machines as unacceptable because

lubricant metal, which is removed by machining so the air flow rateof their roller guideways. Consequently, by devising the shape ofreaches the target value. Although it takes more time and effort

the needle insertion area on the moving side and improving thethan the inherent restrictor system, this results in 1/8th the air flow

finishing method on the guideway surface, a value of 10 nm or

rate, 2.3 times the axial rigidity, and 1.7 times the radial rigidity.

less for the micro-waviness was obtained, and a surface roughness

The center runout (SPAM) of the work spindle is also 2 to 3 nm. As

of 2 to 3 nmRz was easily achieved in the cutting results. This

shown in Fig. 36, the results of machining with this spindle show no

product received high marks from users because of its high rigidity,

distortion in the pull line and the feed pitch per turn can be clearlyexcellent stability without a heat source like hydrostatic bearing

seen. Furthermore, the work spindle has a C-axis function, whichmachines, and energy savings (only 0.4cc of lubricant per axis per

enables smooth speed changes by issuing the speed command

day was required). The limited V-V roller guideway was supported

in units of 0.01 min-1, thereby contributing to improved efficiency

by a large number of rolling elements, and the load per needle

and machined surface quality through constant peripheral speed

was 10 N or less. Since many rolling elements are in contact, themachining even in the field of ultra-precision machining.40)

damping effect is large, and the position deviation is stable at 0.5
nm during stopping as shown in Fig. 33 due to the suitable contact
friction.39)

New ProductX-axis0.5nm
SeriesZ-axisFig. 34

Machined surface with inherent restrictor bearing

Patent News

Fig. 33 Position deviation at X and Z-axis stoppage② Development of porous restrictor aerostatic spindle
The work spindle employs an aerostatic bearing with an inherent
restrictor. The inherent restrictor system has a large bearing

Prepared Critiqueclearance, high air flow rate, and low heat generation for highspeed rotation. The maximum speed of the work spindle in theultra-precision aspheric machine tool is 3000 min-1, and so there islittle concern about heat generation. However, the mirror surface
machined by the work spindle with the inherent restrictor has a

89

Shibaura Machine Engineering Review

Fig. 35

Porous restrictor work spindle

thrust and high heat generation. Toshiba Machine decided to use

featuring high rigidity and high stability, and a FANUC cored linear
motor with high thrust (high efficiency) and low heat generation
for compatibility with the controller. In addition to the strong

Introductory Notea cast iron bed with high rigidity, a limited V-V roller guideway

attachment of the magnet and coil and the placement of themagnets opposite each other to cancel the attractive force, we

the linear motor and feedback scale and the magnetic field lines,
improved the function of the servo system, and adjusted theSpecial Article

devised a mechanism to continuously change the position ofcontrol parameters for building a complete feed mechanism which③ New Technology for Feed Drive System: Cored Linear Motor

is not affected by cogging (Fig. 37).
Technical Paper

Fig. 36 Machined surface with porous restrictor bearing

Limited V-V roller guideway
Table

Drive
AC servomotors and ball screws have been used for the feedmechanisms of ultra-precision machine tools, but bends and

BedTechnical Reportmisalignments in the ball screws affect the behavior of the moving
components and mechanisms have been implemented to absorb
these errors. Parallel spring joints with rigidity in the feed direction

Magnetand degrees of freedom in the direction perpendicular to thefeed direction have been developed and used for ultra-precision

low because the ball screw drive consists of many parts, including

Fig. 37 Limited V-V roller guideway of linear motor drive
Magnets are placed opposite each other to cancel the attractiveforce

and quadrant protrusion due to lost motion always occurs at theguideway do not need to be cooled in the ultra-precision asphericquadrant switching point in simultaneous 2-axis machining. Evenmachine tool, where the maximum feed rate is about 1000 mm/

by changing the machining conditions, such as slowing downmin, contributing to energy-saving operation. The high levelthe feed at the quadrant switching point, or by machining with aof perfection of the limited V-V roller guideway and the linear

compensation program to predict the quadrant protrusion, it was

motor drive have enabled us to achieve 10 nm or less for the

not possible to eliminate the penetration caused by the quadrant

micro-waviness, tracking performance within 0.5 nm or lessprotrusion. Therefore, there was no other way but to remove itwith movement commands, and no lost motion when switchingby polishing after machining, which took time and caused loss ofquadrants, making the term "quadrant protrusion" a thing of theform accuracy. Also, the ball screw needed to be replaced afterpast.
In the limited V-V roller guideway used for the X and Z axes, thedirectly affected lost motion. And so, we studied the applicationneedle is preloaded by the weight of the moving component, but

of linear motors, which have fewer parts and a simpler structure

as shown in Fig. 38, a method to reduce the weight of the moving

than ball screw drives, as a new feed mechanism for ultra-precisioncomponent is also employed by using the attractive force of themachines.

magnet as a preload. In Fig. 29, the method of applying a preload toCoreless linear motors are used in ultra-precision machines

a limited V-V roller guideway for a vertical guideway was described

and light-load machining centers to avoid the effects of cogging

earlier. However, the latest machines have employed a method

and magnet attraction, but they have the disadvantage of low

which uses magnetic attraction instead of aerostatic bearings

Shibaura Machine Engineering Review

90

Prepared Critiqueabout three years of operation because wear of the ball screw

Patent NewsAs a result of employing a cored linear motor, the coil andSeriesthe servo motor, coupling, ball screw, nut, and parallel spring joint,

New Productaspheric machine tools. However, the rigidity of the feed system isIntroductory Note
Special Article

in order to simplify the structure, reduce costs, and improve

Through the production of these elemental technologies, we

performance. Thus, the use of cored linear motors has greatly

have developed improvements to machining and measurement

contributed to the accuracy, performance, and stability of ultra-

technologies and come to better understand the hurdles presented

41)

by sub-micron technology. The breakthrough for ultra-precision

Since 2010, the addition of digital cameras, smartphones,

machining was not the upgrading of conventional machine

security cameras, industrial cameras, and in-vehicle cameras has

elements, but the challenge of completely new technologies suchcreated a huge demand for aspherical lenses (glass and plastic).

as aerostatic spindles, aerostatic guideways, limited V-V roller

Toshiba Machine has responded to this demand by expanding theguideways, and cored linear motor drives.

precision aspheric machine tools.

Technical Paper

specifications and functions of its ultra-precision aspheric machine

In 1977, there was almost no need for ultra-precision machining

tools (on-machine measurement system, 0.1 nm commands, etc.),

in Japan, and we simply supplied aerostatic spindles to research

improving accuracy, and developing machining methods (ellipticalinstitutes for research purposes. However, as mentioned earlier, wevibration cutting, constant peripheral speed control, etc.) anddemonstrated optical mirror surfaces can be produced by cutting

machining software for contributing to the delivery of more thanwith an experimental device combining an aerostatic spindle and1000 units to date.

an aerostatic guideway, and the results were applied to machine
tools for polygon mirrors and magnetic disk substrates, and theLimited V-V roller guideway

Table

improved performance and accuracy of the aerostatic spindle
and V-V sliding guideway were used in ultra-precision slicers. The

Technical Report

limited V-V roller guideway and cored linear motor drive have beenused in the ultra-precision double-column machining centers (light
guiding sheet metal machining). The limited V-V roller guideway,
cored linear motor drive, and porous restrictor aerostatic spindle
have been used in ultra-precision aspheric machine tools, and the

New Product

Bed

Magnetultra-precision hydrostatic spindle and limited V-V roller guideway,
and cored linear motor drive have been used in ultra-precision

Fig. 38 Limited V-V roller guideway of linear motor drive
Attractive force of magnets is used to apply a preload

grooving lathes (roll machining for prism sheets).
Laser printers, hard disk drives, liquid-crystal displays, digital

3

Conclusion

cameras, camera phones, smartphones, security cameras, and invehicle cameras involving these machine tools were unimaginable

SeriesPatent News

Our company has been involved in ultra-precision machining

in 1977. It is not clear whether ultra-precision machining

since 1977, with the aim of differentiating and adding value

technology made these products possible, or whether theto our products by improving machine tool accuracy. In thisrequirements for these products drove the development of ultra-

context, we introduced high-precision machine tools (lathes,precision machining technology, but I believe the above products

cylindrical grinders, surface grinders, jig borers, etc.) and a

are the result of ultra-precision machining technology being able

constant-temperature factory at ±0.1 °C as machining equipment,

to meet the requirements of the products.

Prepared Critique

improved the scraping and lapping skills (production of three-

Although we were not able to make much of a contribution

face sliding surface plates), and introduced capacitance-type non-to the upgrading of machine tools which we had envisioned atcontact micro-displacement sensors, roundness meters, surface

the start of ultra-precision machining in 1977, it has been a greatroughness meters, differential interference microscopes, andpleasure to be involved in and contribute to the birth of completely

Fizeau interferometers as measuring instruments. As elemental

new industries and product groups over the past 40 years.

technologies to achieve submicron accuracy, we have developed
aerostatic spindles, aerostatic guideways, V-V sliding guideways,
limited V-V roller guideways, and more.

91

Shibaura Machine Engineering Review

Technical Report
New Product
SeriesPatent News
Prepared Critique

92

Technical Paper

Shibaura Machine Engineering Review

Special Article21) Toshiba Machine Technical Report: Air bearings and mirror
finishing for ultra-precision machining (1980).
22) Katsunobu UEDA, Mitsuo SUMIYA: Diamond cutting of metal
mirrors for carbon dioxide laser equipment, Toshiba Review, 40,
10 (1985) 857.
23) Katsutoshi TANAKA: Machining by SPDT, Edited by Naoharu
KINOSHITA, Diamond Tools, Nikkei Gijutsu Tosho (1987) 764.
24) Mitsuo SUMIYA: Planar and spherical mirrors, Edited by Naoharu
KINOSHITA, Diamond Tools, Nikkei Gijutsu Tosho (1987) 771.
25) Masao USUKI, Masaomi KUBO, Yoshio MAKIMOTO, Takashi ONOGI:Applications for static pressure elements, Fujikoshi Engineering
Review, 38, 2 (1982) 49.
26) Japanese Industrial Standard, Optical Polygons for Angle
Standards, JIS B7432.
27) Etsuji MINAMI: Diamond cutting of polygonal mirrors for laser
printers, Machine Tool & Machine Technology, 7 (1985) 116.
28) Nippon Light Metal Technical Report, Special Aluminum Alloy
Material for Laser Scanner Mirror (Polygon Mirror).
29) Katsutoshi TANAKA: Mirror machining of polygonal mirrors, New
Machining Tool Encyclopedia, Sangyo Chosakai (1991) 629.
30) Katsutoshi TANAKA: Structure, accuracy and application examples
of aerostatic guideways, Machine Tool & Machine Technology, 8(1987) 110.
31) Yujiro AKECHI: Spindle Head Design for Ultra-precision Lathe,
Journal of the Japan Society of Precision Engineering, 45, 10 (1979)
1182.
32) Bryant Symons, Fine Diamond Tool Lathes, Catalog.
33) Katsutoshi TANAKA: Chapter 11, Ultra-Precision Lathes, Edited by
Hiroshi EDA, Ultra-Precision Machining Technology, Triceps No. 2(1986) 307.
34) Katsutoshi TANAKA: Current state of grooving and cutting by
ultra-precision slicers, Journal of the Japan Society for Abrasive
Technology, 46, 11 (2002) 544.
35) Katsutoshi TANAKA, Seiji KIMURA, Kiyoshi SUZUKI, Tetsutaro
UEMATSU: A Study on achieving high accuracy in ultra-precision
machine tools: 1st report: Improvement of performance of anaerostatic bearing spindle with an annular restrictor, Journal of
the Japan Society for Abrasive Technology, 51, 5 (2007) 302.
36) Etsuo TAKEOKA: A Study on End Milling of High-Hardness
Materials by High-Speed Aerostatic Spindles, Thesis (1998).
37) Katsutoshi TANAKA, et al., A Study on achieving high accuracy
in ultra-precision machine tools: 3rd report : A Study on an ultraprecision aspheric generating machine and its performances,
Journal of the Japan Society for Abrasive Technology, 51, 9 (2007)
553.
38) Hirofumi SUZUKI: Research on Ultra-Precision Machining ofAspheric Optical Components, Thesis (1997).
39) Yoshiaki KAI: A Study on the Analysis and Evaluation of the
Dynamic Characteristics of Ultra-precision Machine Tools, Thesis(2015).
40) Rei SEKIGUCHI et al.: Higher Efficiency for Ultra-Precision Grindingof Glass Lenses by Controlling the Tool Feed and Workpiece
Peripheral Velocity, Proceedings of the 2015 Japan Society for
Abrasive Technology, 332-337.
41) Katsutoshi TANAKA, et al., A Study on achieving high accuracy
in ultra-precision machine tools: 2nd report: Investigation on
the performance of the V-V roller guide-way table driven by alinear motor with cores, Journal of the Japan Society for Abrasive
Technology, 51, 8 (2007) 482.

Introductory Note

References
1) Katsutoshi TANAKA: Ultra-precision machining contributing to
information-oriented society, Journal of the Japan Society for
Abrasive Technology, 50, 10 (2006) 563.
2) Isao HARUMOTO, Kunio WATANABE: Manufacturing technology
of aspheric lenses, Science of machine, 28, 9 (1976) 1071.
3) Kazuo NAITO: Ultra-precision technology in camera production Mass-production technology of high-precision asphericlenses - Journal of the Japan Society of Mechanical Engineers,87, 791 (1984) 1152.
4) Akira KOBAYASHI: Recent ultra-precision cutting technology,
Science of machine, 33, 1 (1981) 97.
5) Masakazu MIYASHITA: Overseas trends in ultra-precision
technology, Journal of the Japan Society of MechanicalEngineers, 87, 791 (1984) 1109.
6) Yoshitaro YOSHIDA, Kimiyuki MITSUI, Yuichi OKAZAKI: Ultraprecision machine tools and their elements, Journal of the Japan
Society of Mechanical Engineers, 87, 791 (1984) 1116.
7) Yorikazu SHIMOTSUMA: Outlook for hydrostatic gas bearings
in foreign countries, Journal of Japan Society of Lubrication
Engineers, 15, 9 (1970), 544.
8) D. M. Miller, G.H. Hauver, J.N. Culverhouse,
E. N. Greenwell: Description of a Unique Machine Tool Permitting
Achievement of <15-Årms Diamond-Turned Surfaces, SPIE Vol.163
Advances in Optical Production Technology (1979) 55.
9) Akira KOBAYASHI: Recent Development of Ultra-Precision
Diamond cutting Machines in Japan, Special Lecture on
Ultra-Precision Diamond Cutting, Japan Society for Precision
Engineering, (1984) 1.
10) Akira KOBAYASHI : Ultra-Precision Machining Technology Historical Development and Future Expectations, Special Lecture
on Ultra-Precision Diamond Cutting, Japan Society for Precision
Engineering, (1984) 9.
11) J. W. Pearson: Precision Machining Commercialization, Japan
Society for Precision Engineering, Special Lecture on UltraPrecision Diamond Cutting, (1984) 31.
12) Floyd E. Johnson: Diamond Turning at Honewell, Japan Society
for Precision Engineering, Special Lecture on Ultra-Precision
Diamond Cutting, (1984) 39.
13) PNEUMO PRECISION, INC., Micro-Surface Generating Pneumo
Model MSG-325 Catalog.
14) P. Donald Brehm: Diamond Machining of Metal & Plastic Optics,
Japan Society for Precision Engineering, Special Lecture on UltraPrecision Diamond Cutting, (1984) 23.
15) T. G. Gijsbers, COLATH, A Numerically Controlled Lathe for VeryHigh Precision, Philips Mechanical Review, 39, 9 (1980).
16) Hideo TSUWA: The present and future of ultra-precision
machining, FOP, 4, 8 (1979) 1.
17) Norio TANIGUCHI: Development of ultra-precision machining
technology and its future issues -Relation to nanotechnology,
Journal of the Japan Society of Mechanical Engineers, 87, 791(1984) 1101.
18) Katsutoshi TANAKA: Air bearings and ultra-precision machining,
Science of machine, 34, 12 (1982), 1304.
19) Mitsuo SUMIYA, Katsunobu UEDA , Tameyasu TSUKADA:
Performance and Application of Developed Ultra Precision
Air Bearing Spindle, Journal of the Japan Society of Precision
Engineering, 45, 10 (1979) 1231.
20) Akira KOBAYASHI: History of the development of high-precision
air bearing rotating axes and their applications, Japan Society ofPrecision Engineering, 45, 10 (1979), 1159.

Patent News

Introductory Note

Introduction to Patents
Establishing the "respect for intellectual property rights" as one of its corporate policies, SHIBAURA MACHINE protects
the results of technological development by establishing intellectual property rights, and also respects the intellectual
property rights of third parties. SHIBAURA MACHINE strives to promote the development of technologies to offer products,
systems, and services which can satisfy customers. As a result, the company holds approximately 1,800 domestic andSpecial Article

overseas patent rights. Of those patents, SDGs-related patents will be introduced herein. Such patents are highly evaluatedby the patent score provided by Patent Result Co., Ltd. (Patent score: an evaluation index for scoring the level of attention
to individual patents based on historical information)

Technical Paper

1

Deep ultraviolet LED and method
for manufacturing the same

Technical Report

Patent number: Patent No. 6230038
Inventors:
Mitsunori KOKUBO, Takaharu TASHIRO (SHIBAURA MACHINE),
Yukio KASHIMA, Eriko MATSUURA (Marubun), Hideki HIRAYAMA(RIKEN), Ryuichiro KAMIMURA, Yamato OSADA (ULVAC), Toshiro
MORITA (Tokyo Ohka Kogyo)

2

Glass forming moldPatent number: Patent No. 5376984
Inventors: Hisanori FUWA, Jun MASUDA

In order to prevent reaction with glass, mold release film isapplied to the mold during glass lens manufacture by means of

New Product

Deep ultraviolet LEDs are expected to be widely used forpress forming. Typical mold release film uses noble-metal based

sterilization in food, water purification, medical, and homealloys, such as oxidation-resistant platinum and iridium. However,electronics industries. However, power conversion efficiency of

depending on the glass type combination, such mold release film

the product is only 2% to 3%. To put the deep ultraviolet LED into

has low mold-release properties, causing the glass to fuse in apractical use in the above industries, a power conversion efficiency

short amount of time. Therefore, a mold release agent was appliedof 10% or higher is required. Major factors contributing to low power

to the mold on which an iridium-rhenium alloy mold release film

conversion efficiency are; <1> 50% or more of deep ultraviolet light

was formed before molding the glass, or mold release coating wasis absorbed and disappears in the contact layer of the LED, and <2>applied to the glass preform.

Serieslight extraction efficiency is sometimes less than 10% because deep

The glass forming mold according to the patent has a mold releaseultraviolet light is converted to heat due to total internal reflection.

layer containing carbon inside the mold. Because carbon contained

To improve power conversion efficiency, improvement of lightin the mold release layer works similarly to the mold release agent,

extraction efficiency is required.

excellent mold release performance can be achieved without

Patent News

With respect to this LED patent, light extraction efficiency of up to

applying a mold release agent to the mold and glass preform. The

about 60% has been achieved by adopting an appropriate stacking

mold use cycle is generally between 100 and about 500 times.

sequence of substrate electrode layers, periodic photonic crystal

However, SHIBAURA MACHINE's mold can now be used even morestructure, nanopillar structure, and semispherical lenses.

than 2000 times.

Light extraction eff iciency
About 60% maximum

Mold release
layer

Prepared CritiqueLight extraction eff iciency
Less than 10%

Sapphire lens

Sapphire substrate

Quantum well layer
Various types ofelectrode layers

Nanopillar layer
Quantum well layer

Reflection electrode layer

Photonic crystal cycle layer
Reflection electrode layer

Conventional deep
ultraviolet LED
93

Conventional glass
forming mold

Sapphire substrate

Shibaura Machine Engineering Review

Deep ultraviolet LED
according to the patent

Various types of electrodelayers

Cross-sectional drawing of theglass forming mold according
to the patent

Molding method and apparatus ofmolded article of composite material

Patent number: Patent No. 6522456
Inventors: Masamichi MOMONO, Takamitsu YAMASHITA

4

Coating robot system

Introductory Note

3

Patent number: Patent No. 5437301
Inventor: Yuji NEGISHI

In the general coating system, various types of robots are disposed

and other vehicles, housing equipment including modular baths,

according to a plurality of different processes, such as basecoat,and recently, robots and drones. However, fiber reinforced plastic

middle coat, and overcoat. One resulting problem is the system

has a problem where reinforced fibers tend to be oriented to therequires a large installation area. Since two or more robots are useddirection of resin flow, causing molded products to warp, reducing

for coating, it is necessary to program each robot to learn the details

strength in a specific direction. To solve this disadvantage, materialsof the coating procedures.
In the coating robot system according to the patent, the arm ofHowever, such fibers easily break when the material is packed in a

one robot is equipped with several spray guns, which enables one

mold because the fibers of such materials are originally short, thus

robot to perform multiple coating processes. As a result, it is possible

losing a primary advantage of reinforced fibers.

to reduce the installation area of the entire system and reduce theIn the molding apparatus according to the patent, <1> it isTechnical Paper

with mixed reinforced fibers have been used for forming plastic.

Special Article

Fiber reinforced plastic is widely used for aircraft, automobiles,

learning tasks of the robot.

possible to continuously load reinforced fibers, and <2> it is possible
Technical Report

to laminate layers so the direction of resin flow varies. Accordingly,
long reinforced fibers remain in the final molded product without
breakage, and long reinforced fibers in the first layer and the second
layer are formed in opposite orientation. As a result, it is now possible
to obtain high-strength molded products having significantly
Conventional coating
robot

Coating robot according
to the patent

New Productimproved bending strength and modulus of elasticity independentof the direction.

SeriesConventional injectionmolded article

Injection-molded article
according to the patent
Patent News
Prepared Critique

Shibaura Machine Engineering Review

94Introductory Note

High-strength, high-damping-capacity
cast iron manufacturing method

5

Patent number: Patent No. 6131322
Inventors: Ryosuke FUJIMOTO, Takumi HAREYAMA

Currently, complaints about noise rank high among the sevenSpecial Article

typical environmental pollution types. Specifically, noise comingfrom construction work in urban areas is a big problem, and it
is an urgent matter to reduce noise generated from urban-type
construction machines. To reduce noise from construction work, isadvantageous to increase the vibration damping performance of
hydraulic component materials in heavy machines. For example,

Technical Paper

flake graphite cast iron has vibration damping performance but
its strength is too low to be applied to the cast iron hydrauliccomponents of heavy machines. For this reason, cast iron having
strength equivalent to conventionally-used spheroidal graphite
cast iron is required.

Technical Report

As the result of SHIBAURA MACHINE's research and development,
it was found adding an appropriate amount of specific elements tocast iron can promote both the formation of iron-aluminum carbide
and the spheroidization of graphite. Thus, both high strength andlow vibration cast iron has been successfully achieved. The casing

New Product(blue-colored part in the below figure) of the hydraulic component(piston pump) of heavy machines made of SHIBAURA MACHINE's
high-strength, high-damping capacity cast iron is irrefrangible(high strength) and makes quiet (low vibration) construction work
possible.

SeriesPatent News

Conventional cast ironpump

Prepared Critique95

Shibaura Machine Engineering Review

Pump made of vibration
damping cast ironaccording to the patentPrepared Critique

Introductory Note

My Expectations for Shibaura Machine

Toshiro HIGUCHI

we asked Mr. Takahiko INOKUMA (director and manager of the Sales

my time at Toshiba Machine) began about 50 years ago. I took a

Department at the time), who was the instructor for our design

design exercise class in the Department of Precision Mechanics,

seminar, to manufacture the device. After repeated discussions

Faculty of Engineering at The University of Tokyo. Since it was abetween the project laboratory members and Toshiba Machine, we

small department, they asked engineers from companies with adesigned an ultra-precision machine with 4-axis control capable ofconsiderable amount of practical experience to teach the class.

not only processing micro screws, but which could also be used in

A lecturer at Toshiba Machine who was also a senior member of

research on ultra-precision machining for various applications. The

the department taught me design drafting in an exercise withresulting ultra-precision machine was not only used for research ona positioning table for feeding using ball screws, and I learned

various types of ultra-precision machining, it also contributed to

Toshiba Machine manufactured large machine tools.

the development of excellent human resources playing important

When I was appointed as a professor in the Department ofroles in ultra-precision machining.

lecturers to my department, a relationship which continued forto promote the development of a device capable of obtaining

an extensive period of time. In April 1992, I concurrently started

3D images of organs and insects by sequentially acquiring

working on the Higuchi "Extreme Mechatronics" project at KAST,

cross-sectional images of frozen samples by feeding them on a

the Kanagawa Academy of Science and Technology. We built aper-minute distance basis and cutting them with a rotating blade.

laboratory at KSP in Mizonokuchi, Kawasaki City, where we worked

The result of this research, a 3D internal structure microscope,on the project with a budget of one billion yen over five years. One

was delivered by Toshiba Machine to RIKEN and other researchof the tasks of the project was to research electrostatic motors, andinstitutions. In parallel with this joint research, we also succeeded

we succeeded in developing a powerful electrostatic motor within developing an automatic preparation device for tissue sections

a performance comparable to that of electromagnetic motors. In

used in pathological examinations, which was put on the market

the course of investigating various electrostatic motor systems, weby Toshiba Machine (the technology has since been transferred torealized we needed a device capable of processing 3-row screws

Dainippon Seiki).
The success of this joint research was due to Toshiba Machine's

However, such a device did not exist, so we decided to create one

ability to design and manufacture high-precision, robust machinesourselves using our ample research funds. We happened to comewhich reliably fulfill their functions based on proven technology

across an article in an industrial newspaper reporting Toshiba

and abundant achievements. This is the DNA of Toshiba Machine.

Machine had developed a small aspheric processing machine. On a

The new company name, Shibaura Machine, not only represents

hunch we would be able to develop a machine which could achievea brand name in machine tools, it also stands as a reminder of our

Shibaura Machine Engineering Review

96

Prepared Critiquewith a pitch of several micrometers in order to process electrodes.

Patent NewsIn the KAST project, we collaborated with Toshiba Machine

SeriesPrecision Mechanics in 1991, I requested Toshiba Machine send

New ProductToshiba Machine hereafter because much of the following is about

Technical Report

the desired functions if we used this processing machine as a basis,

Technical Paper

My relationship with Shibaura Machine (I will refer to it asSpecial Article

Emeritus Professor
University of Tokyo

company’s origins with Toshiba. Although Shibaura Machine is no
Introductory Notelonger part of Toshiba Corporation in terms of capital, we trust it
will play a role as a successor to Toshiba's production machinery
business, which has supported the development of Japaneseindustry.
This Technical Bulletin is the first to be published since ourrebranding as Shibaura Machine. Fresh from the field of industry,Special Article

the information contained in the Technical Bulletin is valuable forresearchers and students at universities and other educational
institutions. I hope the Technical Bulletin will continue to be
published for years to come and contribute to advancements inscience, technology, and engineering education.

Technical Paper

As can be seen from this Technical Bulletin, Shibaura Machine
has a number of uniquely distinctive technologies in the fieldsof large machinery, ultra-precision, injection and die castingmachines, and control equipment. In addition to aiming at further
growth in these existing areas, it will be important to develop new

Technical Reportbusinesses which make use of these technologies, and for that, it
is vital to interact with people from different fields. This Technical
Bulletin is an important medium in making the technology of
Shibaura Machine widely known to people in different fields. I
hope the contributors to this bulletin will devise descriptions which

New Productcan be readily understood by people from different specialties,
and thereby convey the content and appeal of the developed
technology to as many people as possible.

SeriesPatent News
Prepared Critique
97

Shibaura Machine Engineering Review

©2022 SHIBAURA MACHINE CO.,LTD.

Shibaura Machine Engineering Review

98