Technologies of High-Precision
5-Axis Machine μV1-5X andMachining Examples
HIROYUKI WAKAMOTO*1

TOMOHIRO WAKANA*1
TAKUMA KUBOZONO*1

In the field of high-precision machining in Japan, a required machining accuracy of ±1 μm has become more common for 3-axismachines. Amid this, customers are also beginning to request equivalent accuracy for 5-axis machines. However, achieving suchhigh-precision machining on a 5-axis machine is difficult because it not only has more components but also involves multiple factorsthat can degrade precision. To address this demand, we developed the high-precision 5-axis machine μV1-5X using our unique
technologies, which realizes high-precision machining equivalent to that using a 3-axis machine. The μV1-5X can be applied tohigh-precision machining conventionally performed using a 3-axis machine, in addition to machining complex three-dimensional
shapes accomplished only using a 5-axis machine.

of peripherals including application software. To facilitate
the introduction of 5-axis machines, it was a must to market
a high-precision 5 -axis machine that provides machiningaccuracy equivalent to that of 3-axis machines, so we havedeveloped the high-precision 5-axis machine μV1-5X. The
following are the technologies used in the μV1-5X and theevaluation of its machining performance.

1. Introduction
Recently in Japan, in the field of high-precision processing
including die machining, customers have been actively
considering the introduction of 5-axis machines to improvemachining accuracy. Specifically, they are shifting to 5-axis
machines that can machine five faces without reclamping
the workpiece to minimize machining errors due to setupchanges and, in precision die machining that frequently usesball endmills, they use such techniques as always cuttingwith the tool tilted relative to the workpiece, instead ofcutting by the tip of the tools where the peripheral velocity
is zero, to improve machined surface quality. To addressthese demands, manufacturers are rapidly offering a variety

2. Features of μV1-5X
The μV1-5X is a high-precision 5-axis machine developed
based on the high-precision 3 -axis machine μV1, which
has already gained popularity in the market. The external
appearance and the main specifications of the μV1-5X areshown in Fig. 1 and Table 1, respectively. As to structural

Table 1 Specifications of μV1-5X
X-, Y-, and Z-axes (Linear axes)
B-axis (Tilt axis)
C-axis (Rotation axis)
Working surface
Max. workpiece size (Outer diameter)
Max. loading capacity
Rotational speed
Taper size
X-, Y-, and Z-axes (Linear axes)
B-axis (Tilt axis)
C-axis (Rotation axis)
Tool storage capacity
Max. tool diameterMax. tool length
HeightFloor area (Width x Depth)
WeightAxis travel

Table
SpindleFeedrate

Automatic Tool
Changer (ATC)Machine size& weightFig. 1 External appearance of μV1-5X

450 × 350 × 300 mm
130° (−10° to +120°)360° (Continuous)
100 mm
160 mm (Shape limited)
20 kg
400 to 40 000 min-1
HSK−E32
15 000 mm/min
75 min-1
100 min-1
18 tools (Optional : 30 tools)
40 mm
130 mm
2 370 mm
1 920 × 2 054 mm
5 500 kg

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Technical Review Vol. 45 No. 3 (Sep. 2008)*1 Machine Tool Division39

enabling the positions of the workpiece and the tool duringmachining to be viewed easily in front of the operator.

X

3. Accuracy improvements in μV1-5X
ZY

On a 5 -axis machine, geometric deviations on the tilt
and rotation axes must be considered in addition to thoseinherent to a 3-axis machine. Improving machining accuracyof a 5 -axis machine depends on how the accumulation ofthese additional deviations can be reduced. Therefore,
in developing the 5 -axis machine μV1-5X that provides
machining accuracy equivalent to that of 3-axis machines,
we conducted a simulation analysis on how the geometricdeviation and positioning accuracy of each machine element
affects the machining accuracy and yields the optimum
values.
Using the schematics we extracted 13 deviation itemswith respect to the geometric deviations that arise on bothBCFig. 2 Drawing of μV1-5X

form, the μV1-5X is a table-swivel type machine with a tiltaxis (B-axis) and a rotation axis (C-axis) on its table. Figure 2 isa drawing of the μV1-5X. It is designed to prevent machining
accuracy from being affected by inertial forces generated
by acceleration or deceleration of axis travel on both the Band C-axes during machining on the workpiece side and on
the spindle side, by laying out the tilt axis (B-axis) in parallelwith the Y-axis and using mainly the X-axis on the spindleside to feed the workpiece in a longitudinal direction. This
structural form also has advantages in removing the chips
produced during machining because they are ejected tothe front and right/left sides of the tilting rotary table andZ’Z

Z(x,y,z)(xT,yT,zT)
RCC
RB(Xs,Ys,Zs)
Om

B

XX’X

Om
YY’Spindle sideYTilting rotary table side

Fig. 3 Geometric deviations on spindle and tilting rotary table

Table 2 Geometric deviations and positioning accuracy

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Technical Review Vol. 45 No. 3 (Sep. 2008)40

the spindle side and the tilting rotary table side. Figure 3
outlines these geometric deviations. We then added 10 items
that represent the positioning accuracy of each axis and, fora total of 23 items, determined the optimum values so thatthe circularity is maintained at 2 μm or less in simultaneous
5-axis machining of a φ80 cone frustum. Then, we adjusted
the machine based on these optimum values and obtained
the results shown in Table 2. Although there are three items
in which the actual value is worse than the optimum value,adjustments were made to improve the accuracy for otheritems. The resulting machining accuracy of the μV1-5X will be
provided in the next “Examples of machining with μV1-5X”
section.

each of the three linear axes ( X-, Y-, and Z-axes) and thetwo rotation axes (B- and C-axes). Figure 4 shows how themachine was set up for the cone frustum machining andFig. 5 shows the resulting circularity data. The circularity
results show that the μV1-5X, after the abovementioned
adjustments for accuracy improvements, could attain acircularity of 1.95 μm/φ80 mm, the same level of the target
machining accuracy, in the simultaneous 5-axis machining
taking error factors for all of the five axes into account. For
reference, the circularity obtained in 2-axis machining (Xand Y-axes) using the same machine was 1.5 μm/φ40 mm,
which means that, although the machining diameter differed,the machine provides a machining accuracy equivalent tothat of 2 linear-axis machining.
4.2 Groove machining before finishing
Next, as a machining example to show that the μV1-5X is
not only a high-precision 5-axis finisher but also a versatile
machine applicable to rough machining, we would like tointroduce groove roughing using a φ8 endmill. For thisgroove roughing example, the infeed amount was set to 1mm, which is the machining limitation of the HSK-E32 with aφ8 endmill. HSK-E32 is the tool holding mechanism adopted
in high-speed and high-accuracy spindles such as one used
for the μV1-5X. Figure 6 shows the machine setup for the

4. Examples of machining with μV1-5X
4.1 Simultaneous 5-axis machining of a cone frustum
Although the JIS standard for the evaluation of 5 -axis
machines is currently being proposed, in general, the cone
frustum finishing method provided in NAS979 is a wellknown standard. Therefore, we conducted simultaneous
5-axis machining of a cone frustum (80 mm outer diameter)
based on this standard, which is described here. First, it
should be noted that “simultaneous 5-axis machining of acone frustum” is a method for evaluating the circularity of
the cross-section when finishing the side surface of a conefrustum shaped workpiece by simultaneously controlling

DEMONSTRATION

THP TR300 U05.00/J 00.09
Resulting LS circularity
Feature nameA
Measurement No.

Datum
Filter type02 FilterShapeSpindle
Gaussian
1-15 upr
100.0 %

Measurement mode Outer circumference
Measurement date
12-06-2008
Measurement time

→Z heightRadius

11 : 18 : 33

86.5 mm
91.3930 mm
90°Fig. 4 Simultaneous 5-axis machining of a cone frustum

Fig. 3 Result of thermal analysis of spindle

180°0°

270°

Fig. 5 Resulting circularity from simultaneous 5-axis machiningof a cone frustum

Fig. 6 Groove machining before finishing

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Technical Review Vol. 45 No. 3 (Sep. 2008)41

the μV1-5X offers capabilities to complete all machining jobs
from roughing to finishing on a single machine; for example,
in addition to the attachment of workpiece jigs, it is capable ofmachining M6 screw holes for automatic chuck jig plates thatare widely used for this class of machines.

Table 3 Cutting conditions for groove machining before finishing

Spindle rotational speed (min−1)

6000

Feedrate (mm/min)

960

Infeed amount (mm)1Tool

Solid carbide 4-blade endmill

Amount of tool overhang (mm)85. Conclusion

25

Workpiece material

NAX55

External lubrication

Dry

T he μV1-5X, developed by optimizing each machineelement, enables high-precision machining not feasible withconventional 5-axis machines. Our future efforts will be on
improving the working efficiency through peripherals suchas machining support equipment. Finally, we will continueto pursue and propose ideal machines that help customers in
the machining industry in high-speed, high value-added, andhigh-efficiency machining.

Table 4 Resulting straightness from groove machining before finishing
X-axis direction

Y-axis direction

groove machining before finishing and Tables 3 and 4 show
the cutting conditions and the resulting straightness data,respectively. According to the results in Table 4, the straightness
is around 2 μm (including surface roughness) in both theX-axis and Y-axis directions, which means that no chatteroccurred during machining and hence the μV1-5X is a robust
machine that withstands roughing. Besides these advantages,

Hiroyuki Wakamoto

Tomohiro Wakana

Takuma Kubozono

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 3 (Sep. 2008)42