International Conference on Trends in Mechanical and Industrial Engineering (ICTMIE'2011) Bangkok Dec., 2011
Effect of Rake Angle and Feed Rate
on Cutting Forces in an Orthogonal Turning
Process
Satyanarayana.Kosaraju, VenuGopal. Anne and VenkateswaraRao.Ghanta
the past and many are continuing for the purpose of
decreasingproduction cost and manufacturing parameters
Abstract-- In this paper, an attempt has been made to study the
effect of rake angle and feed rate on the cutting forces in an
orthogonal turning process. A hollow cylindrical EN8 work piece
was turned using HSS tools for 6 different rake angles (00, 40, 80, 120,
160, 200). A total of 30 experiments were carried out with 5 different
feed rates (0.022, 0.048, 0.088, 0.108, 0.132 mm/rev) for each rake
angle, keeping the cutting speed (35m/min.) and depth of cut (2.5
mm) constant. During the experimentation, the forces were measured
using a 4-component piezoelectric dynamometer. The experimental
results show that the feed force (F x ) is greater than the tangential
force (F y ) and the longitudinal force (F z ) is least in magnitude
irrespective of the tool rake angle. The cutting forces were found to
increase with the increase in feed rate while decrease with the
increase in rake angle.
without reducing product quality.
Fig.1Turning process (a) Orthogonal turning (b) Oblique turning
Baldoukas et al. [6]experimentally investigated the effect of
feed rate and tool rake angle by conducting 24 experiments on
AISI 1020 steel and found that main cutting force has an
increasing tend with the increasing in feed and a decreasing
trend as the rake angle increase.Gunay et al. [7] investigated
the effect of rake angle on the main cutting force by
conducting experiments on AISI 1040 workpiece material.
Experimental results were compared with the Empirical results
according to Kienzle approach and found that main cutting
force has a decreasing trend as the rake angle increased from
negative to positive values. The deviation between empirical
approach and experiments was in the order of 10–15%.
Saglam, et al.[8]have made a comparison of measured and
calculated results of cutting force components and temperature
variation generated on the tool tip in turning for different
cutting parameters and different tools having various tool
geometries while machining AISI 1040 steel hardened at HRc
40. For making a comparison, the main cutting
force/tangential force component for different cutting
parameters and tool geometries were calculated by Kienzle
approach and the temperature values were calculated based on
orthogonal cutting mechanism. Finally, the effects of cutting
parameters and tool geometry on cutting forces and tool tip
temperature were analyzed and found that the average
deviation between measured and calculated force results were
found as 0.37%. Baldoukas et al.[6] investigated
experimentally the influence of cutting depth, tool rake angle
and workpiece material type on the main cutting force and
chip morphology during a turning process. During the
experimental procedure they removed chips and were
collected and evaluated together with the main measured
cutting forces, in order to estimate the optimum rake angle for
each type material. The experimental results show that the
main cutting force has an increasing trend with the increase of
Keywords—Orthogonal turning, piezoelectric dynamometer.
I. INTRODUCTION
I
N metal cutting operation, the position of the cutting tool is
important based on which the cutting operation is classified
as orthogonal cutting and oblique cutting shown in Fig 1.
Orthogonal cutting is also known as two dimensional metal
cutting in which the cutting edge is normal to the work piece.
In turning process the workpiece material is rotated and the
cutting tool will travel, removes a surface layer (chip) of the
workpiece material, producing three cutting forces
components, i.e. the tangential force (F y ), which acts on the
cutting speed direction, the feed force (F x ), which acts on the
feed direction and the radial force (F z ), which acts on the
direction normal to the cutting speed. In orthogonal cutting no
force exists in direction perpendicular to relative motion
between tool and work piece. It was observed that the cutting
forces are directly depended on the cutting parameters i.e.
cutting speed, feed rate, depth of cut, tool material, geometry
and workpiece material type [1]-[5].
II. BRIEF REVIEW OF LITERATURE
In metal removal operations, many researches were carried out in
Satyanarayana.Kosaraju is with the Mechanical Engineering Department,
National Institute of Technology Warangal, 506004.India. (e-mail:
[email protected]).
VenuGopal.Anne, is withthe Mechanical Engineering Department,
National Institute of Technology Warangal, 506004 India.(corresponding
author to provide phone:+91-9493318537 ; fax: +91-870-2459547 ; (e-mail:
[email protected]).
VenkateswaraRao.Ghanta is with the Mechanical Engineering Department,
National Institute of Technology Warangal, 506004.India.
(e-mail:
[email protected]).
150
International Conference on Trends in Mechanical and Industrial Engineering (ICTMIE'2011) Bangkok Dec., 2011
the cutting depth.Lalwani et al.[9]investigated the effect of
cutting parameters (cutting speed, feed rate and depth of cut)
on cutting forces (feed force, thrust force and cutting force)
and surface roughness in finish hard turning of MDN250 steel
(equivalent to 18Ni(250))maraging steel) using coated ceramic
tool. The results show that cutting forces and surface
roughness do not vary much with experimental cutting speed
in
the
range
of
55–93
m/min.
Fang
and
Jawahir[10]investigated the effects of workpiece hardness,
cutting edge geometry, feed rate, cutting speed and surface
roughness on hardened AISI H13 steel bars with CBN tools.
The effects of two-factor interactions of the edge geometry
and the workpiece hardness, the edge geometry and the feed
rate, and the cutting speed and feed rate also appeared to be
important. Especially for honed edge geometry and lower
workpiece surface hardness resulted in better surface
roughness.
In this study, the influence of tool rake angles on cutting
force was determined during machining of EN8 material,
which has well known physical, chemical and machinability
properties. During the experimental procedure the forces were
measured using a Kistler type 4-component piezoelectric
dynamometer.
Density(gm/cc)
Hardness, Rockwell (HRc)
Tensile strength(MPa)
Ultimate
Yield
Elongation at break (%)
7.85
20-25
660
530
7
while turning a ductile material by a sharp tool, the continuous
chip would flow over the tool’s rake surface and in the
direction apparently perpendicular to the principal cutting
edge, i.e., along orthogonal plane which is normal to the
cutting plane containing the principal cutting edge. This is
referred to as “orthogonal turning.” Practically, the chip may
not flow along the orthogonal plane but this assumption is
made for an ideal case.
In pure orthogonal cutting, the chip flow along orthogonal
plane (Πo) and principle cutting edge angle(φ=900) as
typically shown in Fig 2 where a pipe like job of uniform
thickness is turned (reduced in length) in a center lathe by a
turning tool of geometry orthogonal rake (λ=0) and φ=900
resulting chip flow along (Πo) which is also machine
longitudinal plane (Πx) in this case.
III. WORK MATERIAL, CUTTING TOOL AND METHOD
EN8 steel has been used as the workpiece material to
conduct all the experiments. These type of materials are
widely used in the industrial applications. For conducting
experiments hollow cylindrical bar with inner diameter of 19
mm and outer diameter of 24 mm were used. Prior to the
experiments the specimens were turned with 1 mm cutting
depth in order to remove the outer layer, which could appear
discontinuous or unexpected hardening distribution due to
their extrusion production process. The chemical composition
and mechanical properties of the selected workpiece material
are listed in Table I and Table II.
Fig.2 Pure orthogonal turning (Pipe turning)
IV. MACHINE TOOL AND CUTTING CONDITION
Experiments were carried out on a GEDEE WIELER lathe
setup using High speed steel (HSS) cutting tools for the
machining of EN8 hollow cylindrical workpiece, which is
having outer diameter 24 mm and inner diameter 19 mm. A
total of 30 experiments were performed with 6 different rake
angles 0,4,8,12,16,20 at a constant speed of 490 rpm and depth
of cut of 2.5 mm at 5 different feed rates
0.022,0.048,0.088,0.108 and 0.132 as shown in Table III.
TABLE I
CHEMICAL COMPOSITION OF EN8 STEEL
Chemical composition
Carbon, C
Wt %
0.360 - 0.440
Iron, Fe
>= 97.91
Manganese, Mn
0.60 - 1.0
Molybdenum, Mo
<= 0.15
Phosphorous, P
<= 0.050
Sulphur, S
<= 0.050
V. RESULTS AND DISCUSSION
A set of experiments were carried out as per Table III in
order to measure the effect of change in rake angle and feed
rate on cutting force in all three directions. The experimental
results were shown in Table III. The cutting forces were
measured by usingKistler4 component dynamometer are
plotted in graphical manner shown in Fig 3-Fig 8:
Single point HSS (High speed steel) cutting tools were used
in all the experiments. New tools were used for all
experiments to ensure that tool wear is same in all cases.
Different rake angles were produced in each tool with the help
of a tool cutter and grinder machine. The various tool rake
angles are: 0 o, 4 o, 8 o, 12 o, 16 o, 20 o and a constant clearance
angle: 8o were used.
TABLE II
MECHANICAL PROPERTIES OF EN8 STEEL
151
International Conference on Trends in Mechanical and Industrial Engineering (ICTMIE'2011) Bangkok Dec., 2011
TABLE III
MACHINING PARAMETERS AND EXPERIMENTS RESULTS
1
γ0*
Fx
(N)
Fy
(N)
Fz
(N)
0
132.14
58.78
5.69
Cutting forces (N)
f
Group
Expt.No
((mm/rev)
No
Rake angle = 00
Fx
Fy
1000
Fz
500
1
0.022
2
0.044
220.36
101.32
10.14
3
0.088
623.83
217.37
17.84
4
0.108
819.48
262.82
22.36
5
0.132
910.93
306.05
31.27
1
0.022
151.40
62.97
2.62
2
0.044
332.40
125.99
1.33
3
0.088
500.90
191.43
0.47
4
0.108
604.00
222.93
2.66
5
0.132
737.10
267.49
7.55
1
0.022
87.75
54.48
2.41
2
0.044
187.38
111.20
3.99
3
0.088
329.37
191.25
6.03
Feed (mm/rev)
4
0.108
414.29
228.97
8.70
Fig.4 Variation of cutting forces with feed rate at 4o rake angle.
5
0.132
618.08
305.04
14.28
1
0.022
103.04
49.09
3.94
2
0.044
183.77
93.22
8.18
3
0.088
306.04
156.10
11.92
4
0.108
371.81
189.30
15.10
5
0.132
430.57
224.30
21.02
1
0.022
104.69
50.70
3.48
2
0.044
184.41
90.28
5.51
3
0.088
290.85
147.07
8.63
4
0.108
345.62
177.14
9.75
5
0.132
489.41
239.98
14.93
1
0.022
89.75
49.13
7.51
2
0.044
147.88
86.210
12.9
3
0.088
217.62
135.50
18.91
4
0.108
243.77
157.40
19.44
5
0.132
289.15
190.90
25.57
0
0.022
0.048
0.088
0.108
0.132
Feed (mm/rev)
4
5
6
12
16
20
Cutting forces (N)
8
Fy
800
600
400
200
0
Fz
0.022
0.048
0.088
0.108
0.132
Fx
Rake angle = 80
Fy
800
600
400
200
0
Fz
0.022
0.048
0.088
0.108
0.132
Feed (mm/rev)
Fig.5 Variation of cutting forces with feed rate at 8o rake angle.
Fx
Fy
Fz
Rake angle = 120
600
400
200
0
0.022
0.048
0.088
0.108
0.132
Feed (mm/rev)
*Rake angle
The turning process has been assumed to be a pure
orthogonal process. For such an assumption only 2
components of force must exist in the orthogonal plane. From
the experimental results shown in Table III and graphs 3 to 8 it
is clear that for all cases of rake angle and feed force, the feed
force (F x ) > tangential force (F y ) > radial force (F z ). It is also
clear that the values of F z are very small compare to the other
two forces therefore, this force is almost negligible. Hence the
experiments carried out can be assumed to be orthogonal
turning process.
Fx
Rake angle = 40
Cutting force (N)
3
4
Cutting forces (N)
2
Fig.3 Variation of cutting forces with feed rate at 0o rake angle.
Fig.6 Variation of cutting forces with feed rate at 12o rake angle.
Fx
Fy
Fz
Cutting forces (N)
Rake angle = 160
600
400
200
0
0.022
0.048
0.088
0.108
0.132
Feed (mm/rev)
Fig.7 Variation of cutting forces with feed rate at 16o rake angle.
152
International Conference on Trends in Mechanical and Industrial Engineering (ICTMIE'2011) Bangkok Dec., 2011
Fx
Fy
Fz
Cutting forces (N)
300
200
100
0
0.022
0.048
0.088
0.108
0.132
Feed (mm/rev)
300
200
100
0
0
Fig.8 Variation of cutting forces with feed rate at 20o rake angle.
0.048
0.088
0.108
0.132
0
132.14
220.36
623.83
819.48
910.93
4
151.36
332.42
500.89
604.00
737.13
8
87.75
187.38
329.37
414.29
618.08
12
103.04
183.77
306.04
371.81
430.57
16
104.69
184.41
290.85
345.62
489.41
20
89.75
147.88
217.62
243.77
289.15
Fx
Cutting forces (N)
0
4
8
12
16
Rake angle ( degrees)
VI. CONCLUSIONS
In this paper a total of 30 experiments were carried on to
find the effect of feed rate and rake angles on the cutting
forces during orthogonal turning of EN8 steel using HSS
cutting tool. From the results of this work the following
conclusions can be drawn:
1. It was observed that the feed force (F x ) is greater
than tangential force (F y ). It is also observed that the
radial force (F z ) in the present experimental set-up is
very small and negligible when compared to the other
two force components.
2. As the radial force is negligible, the turning of a
hollow cylindrical workpiece makes it more closure
to the orthogonal machining process.
3. The cutting forces increase with the increase in feed
rate.
4. The cutting forces decrease with the increase in rake
angle from 00 to 200.
20
Fig.9 Change in feed, cutting forces with increase in rake angle for
different feeds for F x
TABLE V
EFFECT OF FEED RATE AND RAKE ANGLE ON TANGENTIAL CUTTING FORCE (F Y )
Rake angle
(degrees)
Feed rate (mm/rev)
0.022
0.048
0.088
0.108
0.132
0
58.78
101.32
217.37
262.82
306.05
4
62.97
125.99
191.43
222.93
267.49
8
54.48
111.2
191.25
228.97
305.04
12
49.09
93.22
156.1
189.33
224.26
16
50.7
90.28
147.07
177.14
239.98
20
49.13
86.21
135.45
157.35
190.92
20
From Table IV and Table V it is clear that the cutting forces
decreases with increase in rake angle and the cutting forces
were found to increase continuously with an increase in feed
for all rake angles. This is due to the fact that the volume of
work material coming in contact with the tool or the volume of
material being removed also increases with the increase in
feed rate. It can also be observed from the Fig. 9 and Fig.10
that, the cutting forces continuously increase with feed, the
increase is more prominent at lower rake angles while less at
higher rake angles. This is because the plunging effect of the
tool into the workpiece material at a greater rake angle
overshadows the effect of increase in cutting force with
increase in feed at higher rake angles.
0.022
0.048
0.088
0.108
0.132
Linear (0.022)
Linear (0.048)
Linear (0.088)
Linear (0.108)
Linear (0.132)
1000
900
800
700
600
500
400
300
200
100
0
8
12
16
Rake angle ( degrees)
different feeds for F y
Feed rate (mm/rev)
0.022
4
Fig.10 Change in feed, cutting forces with increase in rake angle for
TABLE IV
EFFECT OF FEED RATE AND RAKE ANGLE ON FEED CUTTING
FORCE (F X )
Rake angle
(degrees)
0.022
0.048
0.088
0.108
0.132
Linear (0.022)
Linear (0.048)
Linear (0.088)
Linear (0.108)
Linear (0.132)
Fy
400
cutting forces(N)
Rake angle = 200
REFERENCES
[1]
[2]
[3]
153
M.E. Merchant. Mechanics of the metal cutting process, ii. Plasticity
conditions in orthogonal cutting. Journal of Applied Physics, vol.
16:318-324, 1945.
M. Gunay, E. Aslan, I. Korkut, U. Seker, Investigation of the rake
angle on main cutting force, Journal of Machine tools &
manufacture.2004, 44, 953-959.
H. Saglam, F. Unsacar, S. Yaldiz, Investigation of the effect of
rake angle and approaching angle on main cutting force and tool
tip temperature, Journal of Machine tools & manufacture.2006,
46,132-14.
International Conference on Trends in Mechanical and Industrial Engineering (ICTMIE'2011) Bangkok Dec., 2011
[4]
[5]
[6]
[7]
[8]
HaciSaglam, FarukUnsacar, SuleymanYaldiz. Investigation of the
effect of rake angle and approaching angle on main cutting force
and tool tip temperature, International Journal of Machine Tools &
Manufacture.2006, 46, 132–141.
[9] D.I. Lalwani, N.K. Mehta, P.K. Jain.. Experimental investigations
of cutting parameters influence on cutting forces and surface
roughness in finish hard turning of MDN250 steel, journal of
materials processing technology.2008, 206, 167–179.
[10] Tugrul O¨ zel ,Tsu-Kong Hsu, ErolZeren. Effects of cutting edge
geometry, workpiece hardness, feed rate and cutting speed on
surface roughness and forces in finish turning of hardened AISI
H13 steel, International Journal of Advanced Manufacturing
Technology. 2005, 25, 262–269.
[11] N. Fang a, I.S. Jawahir. Analytical predictions and experimental
validation of cutting force ratio, chip thickness, and chip back-flow
angle in restricted contact machining using the universal slip-line
model, International Journal of Machine Tools &
Manufacture.2002, 42, 681–694.
Introduction to basic manufacturing processes and workshop
technology, new age international(P) limited, publications,
Rajender sing 2006
Tugrul O¨ zel ,Tsu-Kong Hsu, ErolZeren. Effects of cutting edge
geometry, workpiece hardness, feed rate and cutting speed on
surface roughness and forces in finish turning of hardened AISI
H13 steel, International Journal of Advanced Manufacturing
Technology. 2005, 25, 262–269.
Α.Κ. Baldoukas, F.A. Soukatzidis, G.A. Demosthenous, A.E.
Lontos. Experimental investigation of the effect of cutting depth,
tool rake angle and workpiece material type on the main cutting
force during a turning process. Proceedings of the 3rd International
Conference on Manufacturing Engineering (ICMEN), 1-3 October
2008
Mustafa Gunay, IhsanKorkut, ErsanAslan, UlviSekerExperimental
investigation of the effect of cutting tool rake angle on main
cutting force, Journal of Materials Processing Technology.
2005,166, 44–49.
154