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Study on Cutting Force and Tool Wear while Milling Ni3Al-
Based Superalloy
Liu Xianpeng1, Zhao Zhengcai1, Fu Yucan1, Su Honghua1, Liu
Gaoqun1,2
1College of Mechanical and Electrical Engineering, Nanjing University of
Aeronautics & Astronautics, 210016 China 2 AVIC Nanjing Engineering Institute of Aircraft System 210016 China
Keywords: Superalloy, NiAl base, Milling, Cutting force, Tool wear
Abstract: Ni3Al-based superalloy is a kind of typical hard-to-cut material due to its
low thermal conductivity and high strength at elevated temperatures, which lead to
dramatical tool wear in the milling progress. To understand the cutting force and the
tool wear behavior in milling process, the influence of cutting parameters on cutting
forces and tool wear in the milling of Ni3Al-based superalloy by using carbide coated
milling cutter is investigated in this paper. Through orthogonal experiment, a linear
regression is carried out with the results and an empirical formula for milling forces
applicable to the test condition is derived. The results show that the cutting forces
increase with the increase of cutting feed rate, radial depth and axial depth of cut.
Besides, the feed per tooth is the main factor affecting of cutting force, and axial depth
of cut has greatest influence on tool wear. The proposed research provides the basic
data for evaluating the machinability of milling Ni3Al-based superalloy and the
recommended cutting parameters can be applied in practical production.
Introduction Ni3Al-based superalloy has excellent oxidation and corrosion resistance, which can
maintain high strength at the temperature above 1000℃ [1]. It is very suitable for
manufacturing the blade disc [2-3]. However, the nickel-aluminum alloy generally has a
large coefficient of friction and a lower thermal conductivity, so it is easy to work
hardening in its processing. Work hardening will aggravate the wear of the machining
tool and the cutting temperature and force, thus limiting the widespread use of the
material [4].
Since the Ni3Al-based superalloy has good high temperature properties, many
researchers have studied its machining process, in order to overcome its processing
defects and expand its application area [5]. Pawade et al. [6] set the appropriate range of
cutting speed and depth of cut, in the conditions of feed rate of 0.15 mm/rev, by which
the effects of cutting parameters on cutting force size were concluded: with the increase
or decrease of cutting speed, cutting force appears to decrease or increase. This is
mainly attributed to such a fact that the heat in the shear zone cannot be quickly passed
out, thus the elevated temperature results in the workpiece plastic deformation, material
softening, thereby decreasing the cutting force. Erdogan et al. [7] found that there was a
positive relationship between the feed rate and the internal force of the cutting, which
became larger as the former increased. Liu et al. [8] gave the tool wear, cutting
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Advances in Abrasive Technology XX
temperature and cutting force of the six alloys of GH80A, GH738, GH4169, GH4033,
GH3044, GH3030 and so on. Nalbant et al. [9] experimentally studied the impact of
cutting speed and tool geometry parameters on the machinability of nickel-based
superalloys, and drew the following conclusions: when the cutting speed increased by
66.6%, the cutting force reduced by 14.6%; when the feed rate increased by 20%, the
cutting force increased by 10.4%. Xin and Wang [10] described that cemented carbide
tool was used to cut nickel-based alloy in high speed. The result shows that at a small
feed (f = 0.09 mm/r) and a small cutting depth (ap =0.12mm), the cutting speed could
be up to vc = 120 m/min. Han [11] found that the abrasive resistance of cemented carbide
tool with coating was better than that of ultrafine grain and ordinary carbide ones, as
well as the abrasive wear was attributed to the main cause of the crater on rake face.
Despite lots of works have been performed on the machinability of nickel-based alloy,
most of them focused on the turning process. On the basis of the selected tool materials
and tool geometry, a reasonable selection of cutting parameters can achieve greater
efficiency, and optimize machining effects. To study the tool wear behavior in milling
process and reduce tool wear, the effects of cutting parameters on tool wear in the end
milling of Ni3Al-based superalloy with carbide coated milling cutter is studied.
Experimental Details
The material used in this research is Ni3Al-based superalloy. The chemical
components are listed in table 1. The physical properties of Ni3Al-based superalloy are
as follows:7.83g/cm3 (Density), 280MPa (Tensile strength, yield), 12.39/10-6/K
(Thermal expand coefficient), 9.64W/m-K (Thermal Conductivity), 29HRC (Hardness),
1302―1357℃ (Melting Point).
Table 1 Chemical composition of Ni3Al-based superalloy
C Cr Al Ti Hf W Ni
0.06-0.20 7.40-8.20 7.60-8.50 0.60-1.20 0.300-0.900 1.50-2.50 Balanced
The setup for milling experiment is shown in Fig. 1. The entire machining tests were
carried out on DMG ULTRASONIC 20 linear and the four-component dynamometer
(Kistler-9272B) was used to measure the cutting force. The cutting tools used in the
experiment were carbide coated milling cutters. The geometrical parameters of carbide
coated milling cutters used in the experiment were listed as follows. The cutter diameter
is 3mm, and the spiral angle is 42°.
Fig. 1 Experimental setup
Listed in Table 2 are the used cutting parameters. In order to measure the tool wear,
Cutting tool
Workpiece
Dynamometer
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Proceedings of the 20th International Symposium on Advances in Abrasive Technology 3-6 December, Okinawa, Japan
three-dimension microscope was used to get the tool wear width. From the optical
measurement results, flank wear was observed as the main wear mechanism in the
milling test with carbide coated milling cutters.
Table 2 Cutting parameters used in the experiments
No. axial depth of
cut ap(mm)
radial depth of
cut ae(mm)
feed per tooth
fz(mm/z)
𝑭𝒙
(N)
𝑭𝒚
(N)
𝑭𝒛
(N)
01 0.2 1 0.004 37.64 11.05 53.81
02 0.4 1.5 0.006 76.53 14.50 102.5
03 0.6 3 0.008 118.0 82.32 168.9
04 0.2 1.5 0.008 57.18 15.48 93.80
05 0.4 3 0.004 60.79 50.46 125.1
06 0.6 1 0.006 96.28 21.54 99.43
07 0.2 3 0.006 52.0 50.50 135.8
08 0.4 1 0.008 86.69 9.83 104.2
09 0.6 1.5 0.004 119.4 10.26 118.6
Results and Discussions
Influence of cutting parameters on milling force
The empirical formula of milling force is established by means of multiple linear
regression analysis and Matlab software. The empirical formula of milling force in
exponential form is obtained
𝐹𝑥 = 957.86𝑎𝑝0.74𝑎𝑒
0.10𝑓𝑧0.36
𝐹𝑦 = 103.12𝑎𝑝0.19𝑎𝑒
2.02𝑓𝑧0.41 (1)
𝐹𝑧 = 700.01𝑎𝑝0.32𝑎𝑒
0.77𝑓𝑧0.36
The range analysis of carbide coated milling cutter is carried out in table 3. The main
factors affecting tangential force 𝐹𝑥 and axial force 𝐹𝑧 are ap, fz, ae. The main factors
affecting radial force 𝐹𝑦 are fz, ae, ap. In order to increase the metal removal rate, the
increase of axial cutting depth should not be taken as the first choice to increase the
feed per tooth and the radial depth.
Table 3 The results of range analysis on the cutting force
factors levels 𝑭𝒙 𝑭𝒚 𝑭𝒛
ap
A1 148.89 220.61 217.83
A2 224.01 255.11 224.88
A3 333.68 230.86 263.87
R 184.79 34.5 46.04
ae
B1 77.03 42.42 71.34
B2 74.79 40.24 86.54
B3 114.1 183.26 107.61
R 39.31 143.02 36.27
fz
C1 283.41 257.44 297.51
C2 331.8 314.9 337.73
C3 386.93 429.8 366.9
R 103.52 172.36 69.39
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Advances in Abrasive Technology XX
In Fig.2 (a), (b) and (c), the variation curves of milling forces obtained under different
cutting parameters are shown. In general, the milling force increases with the axial
depth of cut, the radial depth of cut and the feed per tooth when using the SGS carbide
coated milling cutter, which is consistent with the energy consumption principle. These
machining parameters produce lower forces at low and medium levels respectively.
With the increase of the axial cutting depth, the three directions of milling force show
increasing trends. During the machining process, the interaction between the tool and
the workpiece causes the severe plastic deformation in the local area of workpiece, and
the intense friction at the tool-workpiece interface. The material being removed
influences the cutting forces. According to the milling area formula Ac = ap×f, the
increase of feed or axial cutting depth can lead to the increase of milling area. So the
friction between the tool rake face and the workpiece material increases, and the milling
force increases. When the axial depth of cut is less than 0.8mm, the cutting force is low
and the cutting performance is stable. The axial force 𝐹𝑧 increased along with the
increase of feed rate approximately linearly. 𝐹𝑦 and 𝐹𝑥 changed little with the
variation of the feed rate. When feed per tooth is less than 0.01mm/z, the cutting force
is low, the cutting performance is stable. When feed per tooth reaches 0.02mm/z, cutting
edge breaks.
0.2 0.4 0.6 0.8 1.0
50
100
150
200
250
300
Cu
ttin
g f
orc
e/N
Fx
Fy
Fz
Axial depth of cut/mm1.0 1.5 2.0 2.5 3.0
0
50
100
150
200
Cu
ttin
g f
orc
e/N
Radial depth of cut/mm
Fx
Fy
Fz
(a) Axial depth of cut (b) Radial depth of cut
0.002 0.004 0.006 0.008 0.010
40
60
80
100
120
140
160
180
200
220
Cu
ttin
g f
orc
e/N
Feed per tooth/mm/z
Fx
Fy
Fz
(c) Feed per tooth
Fig.2 Effects of cutting parameters on cutting force
Influence of feed per tooth on tool wear
Generally, the cutting time and material removal amount are chosen as the standard
to measure tool life before reaching wear standard. The amount of material removed is
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Proceedings of the 20th International Symposium on Advances in Abrasive Technology 3-6 December, Okinawa, Japan
defined as follow.
V = 𝑎𝑝 ∙ 𝑎𝑒 ∙ 𝑙 = 𝑎𝑝 ∙ 𝑎𝑒 ∙ 𝑓𝑧 ∙ 𝑧 ∙ 𝑛 ∙ 𝑇 =1000∙𝑣∙𝑎𝑒∙𝑎𝑝∙𝑓𝑧∙𝑧∙𝑇
𝜋∙𝑑(mm3) (2)
The effects of feed per tooth on the tool wear are shown in Fig.3. Other cutting
parameters are v= 37.6 m/ min, ap = 0.4 mm, ae = 3.0 mm. The results show that tool
wear increases greatly with the increase of feed per tooth. When the material removal
exceeds 1560 mm3 under feed per tooth of 0.01 mm/z, rapid tool wear or fatigue tipping
of the cutting edge was observed. When feed per tooth is less than 0.01mm/z, tool wear
increases gradually with the increase of material removal. As feed per tooth increases,
the results show that tool wear rate continues to increase due to the increase of cutting
heat and force. Increase of cutting heat will lead to higher cutting temperature, which
will aggravate the failure of coating. Hence, tool wear rate will increase rapidly without
coating under high cutting temperature and large cutting force.
0.1
0.2
0.3
0.4
0.5
0.6
0 500 1000 1500 2000 2500 3000
Material removal/mm3
VB
/mm
0.002
0.004
0.008
0.01
Fig. 3 Effects of feed per tooth on the tool wear
Influence of axial depth of cut on tool wear
Fig. 4 shows that the tool wear under different axial depth of cut is studied. Other
cutting parameters are v= 37.6 m/ min, ae = 3.0 mm, fz = 0.08 mm/z. Under different
axial depth of cut, tool wear increase slowly with the increase of cutting length. When
the axial depth of cut is 0.2mm, the cutting amount of the cutting tool reaches the
maximum in several groups. When the VB value is 0.2mm, 0.4mm and 0.6mm, the
corresponding amount of material removal is 1160mm3, 1880mm3, 3600mm3
respectively. As for the tool wear behavior, a approximately linear tool wear
development with increasing material removal can be observed at the axial depth of cut
0.2mm. As the axial depth of cut increased, the heat generated and cutting force might
increase, so tool wear grows fast. The cutter edge breakage is mainly caused by tool
fatigue wear.
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Advances in Abrasive Technology XX
0.1
0.2
0.3
0.4
0.5
0.6
0 500 1000 1500 2000 2500 3000 3500 4000
Material removal/mm3
VB
/mm
0.2
0.4
0.8
1.0
Fig. 4 Effects of axial depth of cut on the tool wear
Conclusions
1. The feed per tooth has the greatest influence on the milling force, and the effect of
the radial depth of cut is the least.
2. For milling Ni3Al-based superalloy with carbide coated milling cutter, suggested
the milling parameter combination are v = 37.6 m/ min, fz =0.004~0.008mm/min
and ap =0.2~0.8mm.
3. Axial depth of cut have great influence on tool wear. Since feed per tooth does not
increase tool wear rate noticeably, it can be increased according to the tool load to
get higher machining efficiency. Therefore, selecting proper axial depth of cut is
the key factors in extending tool life.
4. To reduce tool wear in milling Ni3Al-based superalloy with carbide coated milling
cutter, the recommended cutting parameters are fz ≤0.008 mm/ z, ap ≤0.4 mm.
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Proceedings of the 20th International Symposium on Advances in Abrasive Technology 3-6 December, Okinawa, Japan
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