TECHNICAL REPORTTOYOPUC-MC70: Development of a CNC Device for Cutting Machines
Y. OHSAKI

Our company has developed the TOYOPUC-MC70 drastically improving the performance of the MC50, thecurrent CNC device for cutting machines. The features of the developed product are 1) the highest level high speed
performance in any cutting machine CNC, 2) improvement of cutting performance through original CNC controltechnology, 3) visualization of NC programs and improved maintainability and safety, and 4) a small size control
system compatible with compact equipment. Machining cycle time is shortened considerably with a CNC system
maximizing the performance of the new CNC device hardware, and operability has been improved so that there is noneed to be aware of NC programs. The maintainability and safety functions have been enhanced to support recordingof machine operation history. Our new development contributes to process integration for the machining of gears by
the e500H4 machining center through the development of a skiving method utilizing our original control technology.
Key Words: CNC, controller, cycle time, NC program, operativity, machining, gear cutting

1. Introduction
CNC (Computer Numerical Control) devices serve
an extremely important role in determining machining
accuracy of workpieces, machine performance such asmachining cycle time, as well as the serviceability andmaintainability and operability of machine tools.
JTEKT has developed CNC devices for our TOYODA
brand grinders since the 1960s and we have maintained
our competitive edge as a top manufacturer of grinders
thanks to this CNC device. In 2010, we utilized thistechnology to develop the MC50, a CNC for cuttingmachines. However, there was still a desire to further
shorten machining cycle time, as well as improve
operability and maintainability.
This report will introduce the TOYOPUC-MC70 which
was developed by fully revising both the hardware andsoftware aspects of the CNC device and has successfully
achieved high speed processing and high functionality.

2. Background and Aim of TOYOPUC-MC70
Development
Machine tools equipped with MC50, the current CNC
device, have poorer processing speed, maintainability,
overall servo performance and cost performancecompared with the products of other companies. It was
imperative to develop a CNC device as a successor tothe MC50 which overcame these issues. There was alsoa strong need from customers to shorten machining
cycle time, which greatly contributes to productivity

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improvement.
In the development of TOYOPUC-MC70, JTEKT not
only aimed to overcome the issues faced by MC50, butalso positioned the improvement of processing speed,which directly links to shorten machining cycle time,
as our greatest aim in order to develop a CNC device
with a performance unrivaled by the CNC devices of ourcompetitors.

3. Details of the TOYOPUC-MC70 Development
3. 1 Development concept and targets
3. 1. 1 Development conceptTOYOPUC-MC70 was developed based on the below
three concepts.
(1) Highest level high speed performance in any cutting
machine CNC
Build a CNC system which maximizes the latest
CPU computing ability and improves NC program
processing speed and CNC-PLC communication speed.
(2) Improvement of cutting performance through original
CNC technology
Characterize JTEKT machine tools with our original
cutting technology utilizing CNC control technology
which has a proven track record on grinders.
(3) Visualization of NC programs and improved
serviceability and maintainability
Through adoption of NCSFC, make it possible toachieve operability of an NC program without theuser’s awareness. In the event of alarms, shorten timeto analyze causes for the alarm as well as shorten

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Table 1 shows the targets of TOYOPUC-MC70
development. There are many target values forthe development items so we have only shown therepresentative values and functions. In regards to highspeed performance, a target was established to shorten
the machining cycle time of model parts on the MC50
(160.5 seconds) to 148 seconds through the adoptionof TOYOPUC-MC70. This 12.5 second difference
was calculated by considering the effects (theoreticalvalues) of a faster CNC internal processing speed andby performing a pre-evaluation using a CNC device
evaluation simulator. Regarding cutting performance,
the target was to develop a simplified command function
cultivated on CNC devices for grinders, a function whichapplied the virtual axis function and gear machining
control. Through these functions, it would become
possible to perform gear machining on a single machine
tool, whereas up until now this had to be performed on
multiple machine tools.

MC50

TOYOPUC-MC70

Current

Target①High speed(Machining cycle 160.5 sectime example)

148 sec②New cutting
function③

Improved
serviceability
andmaintainability−Skiving cycle(process integrationof gear machining)

Operation history
Servorecord function
sampling
Improved servo
functionsampling function

3. 2 Development results(1) Highest level high speed performance in any cutting
machine CNC
By adopting the latest CPU and reconfiguring CNC
internal processing, we achieved high speed NC program
processing and high speed CNC-PLC communication. As
a result of increasing CNC-PLC communication speed,
we achieved a higher M code processing time than theCNC devices of our competitors (Fig. 1).
Furthermore, using high speed CPU, we newly added afunction to minimize the synchronous error displacement
which occurs when both the spindle and the cutting axis
operate during the tapping (thread cutting) process. By
adding this function, it was possible to shorten the time

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Shortest time500MC50Company B Company A

MC70(When MC50 processing time is 100)

Fig. 1 Shortening of M code processing time

Table 1 TOYOPUC-MC70 development targets
Development item100

Cycle time, s

3. 1. 2 Development targets

taken for spindle acceleration/deceleration at the timeof tapping by half thereby shortening tap cycle time.
Through the shift to high speed, we achieved the target
value for cycle time of the overall operation, including thetapping process (Fig. 2).
Processing time ratio

equipment recovery time. (Refer to 3.2 (2), Fig. 4, andFig. 5 for explanations of NCSFC).

180170160150
140130120110100

Target achieved

MC50

MC70Fig. 2 Shortening of machining cycle time(2) Improved cutting performance
Towards the realization of a skiving cycle, wedeveloped a gear processing machine which possesses
a function which applies both a simplified command
function and a virtual axis function, which is a technology
used in CNC devices for grinders. With a simplified
command function to output the command sent to themaster axis also to the slave axis, as well as a commandvirtual axis function which can specify the rotational
speed ratio of the gear-cutting tool axis and workpieceaxis and output multiple travel commands to a single axis,

Turning

Hobbing

Lathe

Hobbingmachine

ShaperChamfer

Gear shaper Chamferingmachine

Boring

Machining
centerLathe + skiving (gear cutting) + chamfering + boring

Machining center

Fig. 3 Process integration through a machining center

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−TOYOPUC-MC70: Development of a CNC Device for Cutting Machines−

the workpiece offset angle can be additionally calculated
and incorporated in the workpiece axis rotation command.
This technology enables the machining of not only spurgears, but also helical gears, to be integrated into the one
e500H4 machining center, and all machining processes
from turning to boring to be completed in a single chuckoperation (Fig. 3).
The NCSFC developed at MC50 is also adopted on
TOYOPUC-MC70. NCSFC (NC Sequential FunctionChart) is a function which displays the NC program
written in G code in machining process operation
sequence in a chart as shown in Fig. 4. The NCSFC isdisplayed in blocks by individual machining processes
and it is possible to assess progress intuitively as there isan automatic scroll to match the machining progress.
Even if customers do not possess specialist knowledgeof G code, they can easily program the skiving cycle
by observing the image of the machining portion
displayed on the machining cycle setting screen shown inFig. 5 while setting the gear element data and machining
conditions, as well as the tool data in a short period oftime.
Display machining㩷
operations in aflow chart㩷(3) Improved serviceability and maintainability
In regards to serviceability and maintainability, we
newly added an operation history record function andimproved the servo sampling function. With the operation
history record function (Fig. 6) it is possible to record
approximately 1 weeks’ worth of operations performedby the operator and confirm operation history on the CNC
screen. Moreover, operation history data can be stored
on external memory. By using this function together withthe existing alarm history record function (Fig. 7), theoperations before and after alarm occurrence and the lead
up to alarm occurrence are clearer, so this is valid in thecause analysis at the time of alarm occurrence.
The servo sampling function has been improved to allow
twice as much data to be saved and a more detailed analysis(Fig. 8). Moreover, by establishing a servo sampling start
trigger function, operability at the time of servo sampling
data acquisition has been improved (Fig. 9).

Able to record, display
and externally store
operation history

Fig. 6 Operation history record function

Fig. 4 NCSFC display screen

Fig. 5 NCSFC machining cycle settings screen

Fig. 7 Alarm history record function

Fig. 8 Servo sampling function

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Fig. 9 Trigger function to start servo sampling

4. Conclusion
This time, we were able to develop TOYOPUC-MC70
as a CNC device for cutting machines which meets theoriginal development targets. We will continue to developfunctions which lead to higher accuracy and expand theapplicable workpiece and machining ranges of the CNC
device for cutting machines. Furthermore, we will use
the advantage of a CNC device made by a machine tool
manufacturer, challenge ourselves to find innovative
machining methods and be a leader in the market.
*1 TOYOPUC is a registered trademark of JTEKTCORPORATION.

References
1)

H. Takahara: JTEKT ENGINEERING JOURNAL,No. 1009 (2011) 91.

Y. OHSAKI**JTEKT ENGINEERING JOURNAL English Edition No. 1012E (2015)

Mechatronics Control Engineering Dept., Machine
Tools & Mechatronics Operations Headquarters

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