 Open Access
 Total Downloads : 2015
 Authors : A.D.Bagawade, P.G.Ramdasi, R.S.Pawade, P.K.Bramhankar
 Paper ID : IJERTV1IS6146
 Volume & Issue : Volume 01, Issue 06 (August 2012)
 Published (First Online): 30082012
 ISSN (Online) : 22780181
 Publisher Name : IJERT
 License: This work is licensed under a Creative Commons Attribution 4.0 International License
Evaluation of Cutting Forces in Hard Turning of Aisi 52100 Steel by Using Taguchi Method
A.D.Bagawade1, P.G.Ramdasi2, R.S.Pawade3, P.K.Bramhankar3
1 S.V.P.M.College of Engineering Malegaon, Baramati, India.
2Dept.of Mech.Engg, Walchand College of Engineering, Sangli, India
3Dept.of Mech.Engg., Dr. Babasaheb Ambedkar Technological University, Lonere, India
ABSTRACT
The machinability of AISI 52100 hardened steel be expressed in terms of the performance variables such as MRR, cutting forces, tool wear, surface finish and surface integrity etc. In this investigation statistical analysis of the process was performed to explore the effect of the input factors on output variables ,i.e. cutting forces (performance measures). The paper first gives background for this study,experimental setup and design are then discussed, along with the experimental observations on the cutting forces. Finally, conclusions are presented. Such knowledge will help to better understand and model the hard machining process.
Keywords: Axial force, Radial force, Cutting force, Hard Turning.

Introduction
Hard turning is an emerging technology that can potentially replace many grinding operations due to improved productivity (increasing production efficiency, high speed machining), increased flexibility (increasing the range of material that can be machined), decreased capital expenses (saving in cost), and reduced environmental waste[1].In hard turning, ferrous metal parts that are hardened usually between (4570 HRc) are machined with the single point cutting tools. This has become possible with the availability of the new cutting tool materials (cubic boron nitride (CBN) and ceramics). Since a large number of operations is required to produce the finished product, if some of the operations can be combined, or eliminated, or can be substituted by the new process, product cycle time can be reduced and productivity can be improved. The traditional
method of machining hardened materials includes rough turning, heat treatment, and then grinding process. Hard turning eliminates the series of operations required to produce a component and thereby reduces the cycle time resulting in productivity improvement [24].While most hard machining research thus far has focused on chip formation mechanisms and tool wear characterization, it is of great interest to study the effect of cutting conditions on chip morphology. It has been observed that the chip dimension changes as cutting conditions change [5] However, there is still no systematic study of cutting forces in hard machining. It can be observed by literature that cutting forces increase drastically when machining materials with hardness higher than about 45 HRc [6,]. According to results establish during hard cutting by Federico M. Aneiro et al. the radial force showed to be the highest, because the depths of cut and the feed rates selected were significantly smaller than the insert nose radius (0.8 mm). As a result, the chip sectional area was very small, which contributes to lower cutting forces [7]. The results of hard cutting, which is different from conventional cutting, indicated that in general, the radial force is the highest followed by the tangential and axial forces[8,9,10].

Experimental technique

Experimental setup
Hardened 52100 bearing steel with a hardness of 48~50 HRc was chosen for experimental studies because of its wide use in both automobile industry and research fields. The chemical compositions of the AISI52100 Steel are shown in the Table 1. Turning operations were performed dry using a ACE design Jobber computer numerical control
lathe. The Non coated CBN cutting inserts (Mitsubishi, Japan) with a negative 50 rake angle and a 0.8 mm nose radius were used for turning experiments.
Table 1 Chem. composition of the work material
C Cr Mn Si S P
0.92 1.06 0.51 0.22 0.039 0.040
The geometry and grade of insert is NP CNMA120408G (Mitsubishi). Inserts are recommended for machining hardened steel and cast iron in finish operations. It is a highly recommended cutting tool material for hardened steel machining because is suitable for high speed finishing of heat treated steel, sintered ferrous alloy and cast iron stability at elevated temperature. Low affinity to iron, thus good surface finishes is possible.The tool holder used for clamping the insert is PCLNR 2525 M (Make WIDIA). It has 95Âº approach angle and – 6Âº back rake angle.

Experimental Design
The experimenters were performed according to
feed rate and depth of cut. These variables have direct as well as indirect effect on the performance of hard turning process. All three levels of every factor are equally represented in 9 experiments. Since the experimental design is orthogonal, it is possible to separate out the effect of each factor at each level.


Results and Discussion
Table 3 presents experimental results of cutting force components (Fx, Fy and Fz) for various combinations of cutting regime parameters according to L9 design. These are the axial or feed component (Fx), radial or passive component (Fy), tangential or cutting force component (Fz)and the resultant force(Fr). The investigations prove that the radial force component is the highest in machining of external cylindrical surface.
Table 3 Experimental results for cutting force components by Kistler Dynamometer
Expt No.
Fx (N)
Fy (N)
Fz (N)
Fr (N)
1
6.561
11.3525
4.9133
14.00
2
11.93
17.8223
8.5144
23.07
3
26.24
51.2695
24.0479
62.65
4
23.40
39.1846
20.4468
50.013
5
42.38
69.1071
35.9802
85.83
6
58.04
97.3511
88.1653
143.59
7
91.94
97.3206
52.2766
143.72
8
36.22
49.8657
45.5017
76.61
9
10.43
24.4141
11.2610
28.84
Taguchi L9 orthogonal array[11,12]. Based on the
experimental work, the results are presented in this paper. It consists of the assessment cutting force components in hard turning of EN 31 Steel. Table 2 presents design layout according to L9 design.
Table 2 Design layout according to L9 design
Expt. No.
Cutting Speed, V (m/min)
Feed, f
(mm/rev)
Depth of cut, d (mm)
1
250
0.03
0.1
2
250
0.04
0.2
3
250
0.05
0.3
4
300
0.03
0.2
5
300
0.04
0.3
6
300
0.05
0.1
7
350
0.03
0.3
8
350
0.04
0.1
9
350
0.05
0.2
The statistical analysis was performed in order to determine the significant factors that have more effect on the cutting force components using MINITAB15 software. The analyzed results were presented using mean effects plots and surface plots. The results predicated by ANOVA at the 95% confidence interval. Hard turning operation involves various input variables that include cutting speed,
While the other two force components shows less values. It is different from the force relation which is valid in the traditional cutting where the main cutting (tangential) force is the highest. The enlightenment is that the chip formation mainly occurs on the tool radius in hard turning and the machining is done with having negative rake angle.

Statistical Analysis of Axial Force (Fx)
Table 4 demonstrates the ANOVA result for axial force. It originate that the depth of cut is the most major cutting parameters for affecting the axial (feed) forces.
Table 4 ANOVA result for Axial force
Source
Sumof
Degrees
Mean
F
PVal.
Squares
of
Sq.
Val.
(SS)
Freedom (DOF)
(MS)
=5
%
V
1698.6
2
849.3
0.90
0.527
f
193.5
2
96.7
0.10
0.907
d
2198.0
2
1099.0
1.16
0.462
Error
1888.8
2
944.4
—
—
Total
5978.9
8
849.3
—
—
Main Effects Plot for Fx
Data Means
Cutting Speed
50
40
30
20
Feed
requires enormous cutting forces to cut the chip. forces, Fx. It is noted that the axial force is very affected by the depth of cut. The effect of machining parameters in For the depth of cut 0.2 to 0.3 mm, successively recorded the increase in components of
Mean
10
250
50
40
30
20
10
0.1
300
Depth of cut
0.2
350
0.3
0.03
0.04
0.05
the cutting combination is also illustrated with the help of surface plot. From Figure 2 it was observed that the cutting forces are minimum at lower values of cutting speed and depth of cut. This could be because of the reduced chip cross sectional area and
the corresponding material removal rate as encountered during machining.
Figure 1. Main effect plot for Axial force Fx
The second factor influencing Fx is the cutting speed. The feed rate has an insignificant effect on axial force. Therefore, based on the S/N ratio and ANOVA analysis, the optimal cutting parameters axial force are the cutting speed at 250m/min, the feed rate at 0.04mm/rev, and the depth of cut at0.2mm.The effect of cutting speed, feed and depth of cut on axial force (Fx) is presented in Figure1.
The effect of cutting speed
It can be seen in Figure 1 that axial force increased as the cutting speed was increased, with different slopes. This is due to the rise in temperature in the cutting zone which makes the metal machined more plastic and consequently the efforts necessary for machining decrease.
The effect of feed rate
The effect of feed rate on cutting forces is shown in Figure1. It can be noted that the increase in feed rate resulted in the decrease increase in cutting forces.
The effects of feed rate on this force is as, the increase in feed rate from 0.03 to 0.04 mm/rev,

Statistical Analysis of Radial Force (Fy)
Table 5 displays the ANOVA for radial force. The feed rate has an insignificant effect on radial force. Therefore, based on the S/N ratio and ANOVA analysis, the optimal cutting parameters are the cutting speed at 250 m/min, the feed rate at 0.04 mm/rev., and the depth of cut at 0.2 mm.Figure 3 shows the main effect plot for radial force (Fy) for cutting speed, feed and depth of cut.
Table 5 ANOVA result for Radial force (Fy)
Source
Sumof
Degrees
Mean
F
PVal.
Squares
of
Sq.
Val.
(SS)
Freedom (DOF)
(MS)
=5
%
V
2794
2
1397
1.39
0.418
f
230
2
115
0.11
0.897
d
3113
2
1557
1.55
0.392
Error
2005
2
1003
—
—
Total
8142
8
—
—
Main Effects Plot for Fy
Fitted Means
decreases components of the cutting forces Fx.If the feed rate increases, the section of sheared chip increases because the metal resists rupture more and requires large efforts for chip removal.
The effect of depth of cut
Figure 1 represents the influence of the depth of cut on the axial forces. With its increase, chip thickness becomes significant what causes the
70
60
50
40
Mean
30
250
70
60
50
40
30
0.1
Cut t ing Speed
300
Dept h of cut
0.2
350
0.3
0.03
Feed
0.04
0.05
growth of the volume of deformed metal and that
Figure 2 Surface plot of axial force (Fx) vs cutting speed and depth of cut
Figure 3 Main effect plot for radial force Fy
The effect of cutting speed
Figure 3 indicates that the force decreased as the cutting speed was increased in range 300350 m/min.
The effect of feed rate
The effect of feed rate on cutting forces is shown in Figure 3. It can be noted that the increase in feed rate resulted in the increase in cutting forces from
0.04 to 0.05 mm/rev.
The effect of depth of cut
For the depth of 0.2 to 0.3 mm, recorded the increase in components of the radial forces, Fy. It is noted that the radial force is very affected by the depth of cut. In 3D surface plot Figure 4 shows that as depth of cut increases from 0.1 to 0.2 there is
Main Effects Plot for fz
Fitted Means
Feed
Cutting Speed
50
40
30
20
Mean
10
decrease in radial force, but for further increase in the depth of cut from 0.2 to 0.3the radial force
250
Depth of cut
50
40
30
20
10
0.1
300
0.2
350
0.3
0.03
0.04
0.05
Figure 5 Main effect plot for tangential forceFz
Figure 4 Surface plot of radial force (Fy) vs Cutting Speed and Depth of Cut

Analysis of Tangential Force (Fz)
ANOVA results are indicated in Table 6 for tangential force(Fz). With the ANOVA it was found that the cutting speed is prevailing factor affecting the tangential cutting force Fz. Figure 5 shows the main efect plot for fortangential force (Fz) for cutting speed, feed and depth of cut.
Table 6 ANOVA result for Tangential force (Fz)
Source
Sumof
Degrees
Mean
F
PVal.
Squares
of
Sq.
Val.
(SS)
Freedom (DOF)
(MS)
=5
%
V
1984.4
2
992.2
1.25
0.444
f
375.0
2
187.5
0.24
0.809
d
1729.0
2
864.5
1.09
0.479
Error
1586.5
2
793.3
—
—
Total
5674.8
8
992.2
—
—
The feed rate has an insignificant effect on tangential force. Therefore, based on the S/N ratio and ANOVA analysis, the optimal cutting parameters for forces are the cutting speed at 250 m/min, the feed rate at 0.03mm/rev, and the depth of cut at 0.2mm.
The effect of cutting speed
It can be seen from Figure 5 the tangential force decreased as the cutting speed was increased, with different slopes.
The effect of feed rate
The effect of feed rate on cutting forces is shown in Figure 5. It can be noted that the increase in feed rate resulted in the increase in tangential forces. If the feed rate increases, the section of sheared chip increases because the metal resists rupture more and requires large efforts for chip removal.
The effect of depth of cut
Figure 5 signifies the influence of the depth of cut on the tangential forces. For the depth of 0.2 to 0.3 mm, we successively recorded the increase in components of the tangential cutting forces.
Figure 6 illustrate the surface plot of Fz, as cutting speed rate increases from 250 m/min to 300m/min, there is increase in tangential force, but for further increase in feed rate the tangential force decreases its magnitude.
Figure 6 Surface plot of tangential force Fz vs Cutting Speed and Depth of Cut
It is observed from the surface plot that cutting speed and depth of cut are influencing effect on tangential cutting force. The three cutting force namely feed force Fx, radial force (Fy) and tangential force (Fz), were measured during hard
turning of work steel of 48~50HRc. Figure 7 shows the radial force was found to become the largest of the three force components at all cutting conditions.
Figure 7 Results of three forces components for all cutting conditions tested
The cutting speed and depth of cut were the most significant factors under the radial force. The radial force showed to be the highest, because the depths of cut and the feed rates selected were significantly smaller than the insert nose radius (0.8 mm). As a result chip, the chip sectional area was very small, which contributes to lower cutting forces.


CONCLUSIONS
The present work reports a systematic experimental study on, the influence of turning parameters on cutting forces in hard turning of EN31 Steel with uncoated PCBN (MITSUBISHI) insert. From the analysis of experimental data and the identified predictive models, the following conclusions can be drawn.
The force relations occurring during hard turning significantly difference from the traditional cutting because the radial force component is the highest here.Thrust force is dominating compared to both others and that for the entire cutting system.
The measured values of the radial force were always the largest between the cutting forces and the cutting speed and cutting depth were the most significant factors under the radial force. With increasing of the cutting speed, the forces reduce due to the raised temperature in the cutting zone.

ACKNOWLEDGEMENT
A. D. Bagawade would like to thank the BCUD, Pune University, Pune, for granting financial support, for this research work, Grant No.390.(201112).This work was achieved in the Center for Advanced Machining Technology Lab. Of BATU,
Lonere(India). Thanks due to support of CAMT Lab of BATU, Lonere (India) and technician M. D. Patil.
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