TECHNICAL REPORT

Development of the FH630SX-i Horizontal Spindle
Machining Center
Y. OKA

H. TSUSAKA

To address the varying market needs concerning the machining of medium-sized workpieces made from steel
and cast iron materials, we have developed the FH630SX-i horizontal spindle machining center based on theconventional FH630S and FH630SX horizontal spindle machining centers, and improved each function.
Key Words: horizontal spindle machining center, high speed, high stiffness, roller guide, thermal displacementcompensation

1. Introduction
Steel and cast iron medium-sized parts are mainly used
for automobiles, airplanes, agricultural and construction
equipment, energy-related devices, etc. Machining
forms vary from high-variety, low-volume production
to low-variety high-volume production and from highspeed cutting to heavy-duty cutting. Therefore, customer
demand for machining equipment in these fields continues
to diversify each year, and equipment rich in features isdesired. Examples include equipment with features suchas a wide machining range that allows flexible production,
high-speed and high-efficiency machining, excellent cost
performance, and high operability that does not require
expert technique.

3. Features of FH630SX-i

2. Purpose of Development

The specifications of FH630SX-i (hereinafter referredto as “this machine”) are shown in Table 1. The overalllayout of the machine is shown in Fig. 2.

Fig. 1 FH630SX-i Horizontal Spindle Machining Center

We have released the FH630S/FH630SX horizontal
machining center (conventional machine) series asmachining equipment for medium-sized parts.
To respond to customer demand and further increaseof product competitiveness in the market, we havedeveloped a FH630SX-i horizontal spindle machining
center equipped with a wide machining range, highproductivity, consistent accuracy, and high operability
based on conventional machines.

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−Development of the FH630SX-i Horizontal Spindle Machining Center−

Table 1 Main specification
FH630SX-i

StrokeX-axismm

Y-axismm

900

Z-axismm

1 050

Distance from pallet top to spindle center

mm

100−1 000

Distance from table center to spindle nosemm

50−1 100Height from ﬂoor to pallet topmm

1 250

Pallet working surface size
Table andpalletWorkpiecelimitations

Rapid feed rate
Feed rate

Cutting feed rate

mm630×630

Max. workpiece swingmm

u1 170Max. workpiece heightmm

1 250

Max. weight on pallet

kg

1 200
OP：1 500

m/min

60

B-axis−1mm

30

X, Y, Z axes

m/min

30

2

6.86（0.7）

X, Y, Z axes

Rapid acceleration X, Y, Z axes
Spindle speedm/s （G）
mm−1Spindle

Tool

Max. tool length

mm

600

Max. tool diameter

mm

u250

Max. tool masskg

27

Chip to Chipsec

3.6

Tool to Tool

sec

2.5

3. 1 Wide Machining Range

1 050
1 050X-axis stroke

Coolant unit

3 585

Magazine

Z-axis stroke Spindle

Spindle cooling unit
Control panel

900

Y-axis stroke

1 250

3 208

u1 170Workpiece
1 500kg

30/22
OP：37/30
OP：30/25

kW

6 885
Table

6 000
OP：6 000
OP：15 000

Spindle output (15 min/continuous)

Tool change time

Pallet changer

1 050

Compared with conventional machines, this machine
is approximately 1.8 times larger, with a maximum
workpiece swing × height of u1 170mm × 1 250mm,
and 1.7 times heavier, with a maximum weight of 1 500
kg. It also has a 1.5 times wider machining range withthe strokes of the X, Y, and Z axis being 1 050, 900,
and 1 050mm. These features allow the loading of large
workpieces of the highest level in the medium class, aswell as the necessary and sufficient machine movements.
In addition, the shortest distance from the table center
to the spindle nose has been reduced from 200mm onconventional machines to 50mm, allowing shorter tools
to be used for the machining of workpieces. Furthermore,
the Z-axis stroke has been lengthened from 850mm to
1 050mm, which reduces the limitations on workpiece
shape, workpiece swing, etc. when a long tool is attachedto the spindle. This expands the range of selection fortooling and fixtures.

Fig. 2 Machine layout

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This machine has a highly rigid structure that canwithstand high-efficiency cutting and high-speed feed,and achieves high productivity by shortening both cutting
time and non-cutting time.
A roller guide is used for the feed portion of thismachine to balance high speed and rigidity. Despite theincreased mass of the moving object as a result of theincreased machining range, rapid feed rate and rapid
acceleration achieve the highest level of speed in thisclass, i.e. 60 m/min, 0.7G (X, Y, Z-axes).
A dual drive system consisting of two ball screws isused for the Y and Z axes, which receive large cutting
resistance. Optimal rib arrangement through CAE ensuresenough rigidity for major parts that support the ballscrews, including the bed, column, table of the movingobject, and spindle. In addition, the guide size and ballscrew diameter have been enlarged to accommodate
the increase in the mass of the moving object due to theexpanded machining range, and the number of guideblocks have been increased to secure necessary andsufficient rigidity.
This machine construction enables the spindle to givefull performance, achieving the highest milling capability
3in this class of 1 250 cm /min (workpiece material S48C).

3. 3 Consistent Accuracy
3. 3. 1 Low Thermal Distortion Design
Machine structure is thermally deformed by thetemperature changes of the room in which the machinetool is installed. Bending and warping caused bytemperature changes alter the relative position of the tooland the workpiece, causing reduced machining accuracy.
Such bending and warping due to thermal distortion
occur when the machine structure has uneven temperature
distribution. Therefore, to prevent the reduction ofmachining accuracy caused by temperature changes,
the machine structure needs to have even temperature
distribution so that it will be insusceptible to bending andwarping due to thermal distortion.
For this machine, non-routine thermal analysis
through CAE was repeated to balance the arrangementof the rib structure of the bed and column to even thethermal capacity. This achieves a more even temperature
distribution against temperature changes (Fig. 3) andreduces machining errors by 27% (Fig. 4), compared withconventional machines.

72[Conventional machine][FH630SX-i]

Even color
is better

Fig. 3 Thermal distribution of column
1Machining error ratio

3. 2 High Productivity

1

Effect of low thermal
distortion design
27%0.73
Effect of thermal
displacementcompensation
80%0.500.14
ConventionalmachineFH630SX-i withoutcompensation

FH630SX-i withcompensation

Fig. 4 Machining error due to room temperature change

3. 3. 2 Real time thermal displacementcompensation function
This machine has a structure that is insusceptible
to room temperature changes due to its low thermal
distortion design, with a newly developed optional
function that calculates and compensates thermal
displacement of the machine in real time to further
achieve consistent machining accuracy.
This function analyzes thermal distortion inside theCNC unit in a similar style to FEM and calculates therelative thermal displacement of tools and workpieces
in the entire range, based on the temperature datameasured by temperature sensors installed in eachportion of the machine and 3D modeling data of themachine. Furthermore, the relative thermal displacement
at each coordinate is converted into Cartesian coordinate
components and spatially compensated as static geometricerrors. FEM analysis normally requires a significant
amount of calculation time, making it difficult to reflect
the calculation results within commands in real time. In
comparison, the JTEKT-developed high-speed calculation
program enables instant analysis of complex thermal
distortion and compensation (Fig. 5).
This thermal displacement compensation function
can reduce 80% or more of the machining errors causedby room temperature changes (Fig. 4). Because ofthis, consistent machining accuracy is secured undersubstantial ambient temperature changes, and the machine
can be warmed up in minimal time, contributing toproduction efficiency and energy conservation.

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

−Development of the FH630SX-i Horizontal Spindle Machining Center−SensorHigh-speed calculation program
developed by JTEKTInterfaceTemperature
dataThermal distortion is analyzed within the CNC in order to calculate the tool tip displacement
based on the actual machine temperature data and 3D modeling data of the machine.

Thermal displacement
estimation logic
Position control logic

SensorReal time calculation ofcomplex thermal distortion

CNC

Real time position control

Fig. 5 Real time thermal displacement compensation system

3. 4 High operability

3. 5 Dialog programming functions

The opening portion of the pallet changer door of thismachine includes the ceiling portion, in considerationof the loading/unloading of fixtures and workpieces by
crane, etc., and prevention of coolant dripping from thecover ceiling onto the operator (Fig. 6).
The ceiling portion of the operator door for debugging
operations also has a wider opening area compared withconventional machines, improving operability and thelighting on the operator’s hands. The main operation
panel is located on the left and can be swiveled so thatthe operator can check the cutting point and monitor ina natural position, similar to conventional machines. Inaddition, this machine has a people-friendly structure,including an angled keyboard that facilitates input tasks(Fig. 7).

The dialog programming functions allow even nonexperts to perform operations, from creating NC programs
to machining products in a short period of time, merely byfollowing the procedures shown on the screen. Equipped
functions include the setup of workpiece coordinate
systems, automatic setup of machining conditions
according to workpiece material, setup of machining
dimensions based on the machining guidance (Fig. 8),
and automatic selection of optimal tools. In addition,
expert know-how can be added to created programs using
this function, allowing the transmission of machining
technology. Furthermore, programs that shorten cycle
time can be created by utilizing our company’s knowhow gained through production lines. These functions
reduce the operation time from attaching workpieces tomachining by approximately 25% (Fig. 9).

Fig. 6 Pallet changer door

Fig. 8 Processing guidanceFig. 7 Operator door

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Approximately
25% reduction

Time, min.

225
Machining

200

Debugging
Creating NC programs
Setting tool data

100

Attaching workpieces,setting machining zero position
0Fig. 9 Working time shortening effect

4. Conclusion
The newly developed FH630SX-i is a machining
center that can respond to various customer needs, withimproved machine specifications, machining accuracy,
and operability compared with conventional machines.
The improved machining accuracy and operability inparticular utilize new technologies that did not previously
exist, providing high added value to customers. We will
endeavor to develop excellent, up-to-date equipment,
while keeping an eye on industry trends and customer
demands.

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Y. Sasaki, H. Iwai, Y. Sakurai and Y. Wakazono:
Research on Thermal Deformation Compensation ofMachine Tools (1st Report) – Development of Thermal
Deformation Estimation Method -, The Proceedings ofthe 2012 JSPE Autumn Meeting, (2012) 677.
Y. Sasaki, H. Iwai, Y. Sakurai and Y. Wakazono: Researchon Thermal Deformation Compensation of MachineTools (2nd Report) – Evaluation of Thermal Deformationof Machining Center -, The Proceedings of the 2013
JSPE Spring Meeting, (2013) 729.
H. Iwai, Y. Sasaki, Y. Sakurai and Y. Wakazono: Researchon Thermal Deformation Compensation of MachineTools (3rd Report) – Machining Evaluation of Real-time
Thermal Deformation Compensation -, The Proceedingsof the 2013 JSPE Autumn Meeting, (2013) 9.
Y. OKA****74

H. TSUSAKA**

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

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