In metal turning, influence of rake angle on cutting tool life.

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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 11, November 2013
ISSN 2319 - 4847
In metal turning, influence of rake angle on
cutting tool life.
,
And
1
M.Tech. Student Green Hills Engineering College Solan, India
2
Professor Green Hills Engineering College Solan, India
3
Principal Green Hills Engineering Solan College, India
Abstract
In order to reduce the production time and energy loss which is being wasted to re sharp the tools when they got blunt during
machining, hence in accordance to this problem, in this research work the effect of rake angles on tool life has been studied. The
various rake angles used are, ,
,
and
while the other parameters like depth of cut, feed rate, cutting speed ,clearance
angle were kept constant. All the experiments were carried out on mild steel with High Speed Steel (HSS) as cutting tool. It was
found that the tool having rake angle of
have maximum tool life.
Keywords: Rake angle, Relief Angle, Wedge angle, Tool Life and cutting speed.
1. INTRODUCTION
In industries even a single second is precious in production sector. Useful production time, money and energy is being
wasted during the re sharpening of cutting/ turning tools. Other than casting, forming, shaping etc. machining is one of
the major operations to be carried out in almost every mechanical industry. During this operation cutting tool cuts the
metal and sometimes need to regrind the tool become necessary to get good surface finish. In accordance to this, it may
require extra time to regrind the tool to achieve the desired requirements. On the other hand if we already choose such
geometry of the cutting tool so that the chances of getting it blunt may be minimized. Hence in this account, it becomes
necessary to find out the influence of geometry of cutting parameters on tool life. The parameters which may influence the
cutting tool life are:
Rake angle: The normal rake angle (α) is the angle measured from a normal to the finished surface in a plane
perpendicular to the cutting edge. This is the angle most frequently specified and the most easily measured.
There are three types of rake angles: positive, negative, and zero.
By changing rake angles cutting forces may be calculated using dynamometers. Further the cutting tool life can also be
calculated. Some related terms are:
Depth of cut: Cutting speed and feed rate come together with depth of cut to determine the material removal rate, which
is the volume of work piece material that can be removed per unit time.
Feed rate: Feed rate is the velocity at which the tool is fed, that is, advancement of cutting tool against the work piece. It
is expressed in units of distance per revolution for turning.
Cutting speed: Cutting speed may be defined as the relative speed between the cutting tool and the surface of the work
piece.
Wedge angle: this is the angle formed by the rake and the relief angle, which is between the rake face and the relief face.
In general: α+β+γ=
(For Orthogonal cutting)
The tool wear may be classified as follows:
 Adhesive wear
 Abrasive wear
 Diffusion wear
 Fatigue
All these are generally present in combination, the predominant wear mechanism depending upon cutting conditions. In
addition to the above sources of tool failure, the following also pertain :
 Micro chipping
 Gross fracture
 Plastic deformation.
These, however, are usually readily identified and the solution is apparent. Cutting tools wear predominantly in different
ways; depending on cutting conditions (principally cutting speed V and un deformed chip thickness t).The most
important types of tool wear for a single point turning tool is wear-land formation and crater formation. Crater formation
is apt to be more important than wear-land formation in situations where cutting temperatures are very high.
[1]
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 11, November 2013
ISSN 2319 - 4847
2. OBJECTIVE OF WORK
The main objective of the current work is to save the production time and energy which is being wasted in re sharpening
the cutting tools by determining the tool life of High Speed Steel (HSS).
3. LITERATURE SURVEY
Sikdar and Chen 2002 [2] focused on the relationship between flank wear area and cutting forces for turning operations
on a CNC lathe without coolant. Flank wear surface area was measured by Talysurf TM series using a software package
whereas cutting forces by Kistler TM piezo-electric dynamometer. The experimental results shows that cutting forces
increase with the increase of the flank wear surface area, greater the flank wear area, the higher will be the friction
between the tool and the work piece resulting in high heat generation, this ultimately raises the value of cutting forces.
Wang et al. 2003 [3] presented an experimental study on mechanism of cutting for orthogonal cutting with tool flank
wear. They showed that tool flank wear does not statistically affect the basic cutting quantities such as the shear angle and
shear stress, both qualitatively and quantitatively, but results in an additional rubbing force on the wear land. They also
showed that tool flank wear results in a substantial increase in the force components and that the thrust force is more
sensitive to tool flank wear.
Yen et al. 2004 [4] focused the effects of edge preparation of the cutting tool (round and chamfer edge) on chip formation,
cutting forces, and process variables like temperature, stress, and strain etc. in orthogonal cutting. With finite element
method (FEM) simulations a fundamental understanding of the process mechanics with realistic cutting tool edges were
provided, also it is possible to estimate the values of process variables that are very difficult to measure by experiment not
measurable for cutting. On the basis of results carried out from the cutting simulation model, an analysis of tool wear is
also possible as it is directly related to cutting temperature, stresses and chip sliding velocity.
Gunay and Aslan 2005 [5] presented an experimental study of the influence of tool rake angle on the main cutting force
for machining rotational parts by sharp cutting tools on well-known material, AISI 1040 .A force measuring
dynamometer was used for this purpose. Depending upon eight different rake angles ranging from negative to positive
and five cutting speeds main cutting force was measured keeping depth of cut and feed rate constant. Based on this study
main cutting force was reduced by increasing rake angle in positive and was increased by increasing rake angle in
negative values.
Huang et al. 2006 [6] worked on the effective monitoring system in order to maintain the cutting tools in good cutting
conditions and to delay the wear time.
Vagnorius et al. 2010 [7] proposed age replacement model. In this study it was assumed that penalty costs are incurred each
time a tool fails before the planned replacement. The probability of such an event is determined from the tool reliability
function. The optimal replacement time is then determined from a total time on test (TTT) plot. The adequacy of the
proposed approach for practical application is tested and confirmed in a case study on turning of Inconel 718 with cubic
boron nitride (CBN) tools.
Sambhav et al. 2011 [8] presented the 3D definition of the faces of a single point cutting tool (SPCT) in terms of 3D
rotational grinding. A mechanistic model is subsequently proposed to predict the forces in terms of the chip thickness,
grinding angles and velocity using second degree polynomial function. The model has been calibrated for HSS tool and
Mild Steel work piece combination for end turning of a tubular work piece.
Tukora and Szalay 2011 [9] focused on predicting cutting force, based on the mechanistic cutting force. In this work it
was found that the proposed way of determining the cutting force coefficients makes it possible to perform the coefficient
determination and the force prediction simultaneously. The results shows that the instant coefficient determination works
properly and the predicted forces gradually approach the measured forces
Usman 2012 [10] studied the effects of tool rake angles on tool life, the different rake angles taken in to consideration are
, ,
,
, and
and a constant clearance (Relief angle) of 80 was used on bright mild steel in turning process
with HSS (high speed steel). The main purpose was to save energy and useful production time during regrinding and resharpening of tools and energy is being wasted due to regrinding or re-sharpening of tools when cutting tools got worn or
blunt. The rake angle which can give the longest tool life was then selected and observed that rake angle having value of
as well as the best surface finish and yielded continuous chips formation.
4. MATERIAL AND METHODOLOGY
Machine tool, cutting tool and cutting parameters:
All the cutting experiments were conducted on precise lathe machine and on same material. The material used in the
experiment was mild steel. Four single point cutting tools HSS (9.53x76.20mm) were used for all the experiments.
Cutting geometry of all the cutting tools was same except the rake angle.
, , and
angles were used and finally
the tool life for respective angles were determined. The angle was obtained by grinding the tool on precise pedestal
Volume 2, Issue 11, November 2013
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 11, November 2013
ISSN 2319 - 4847
grinding machine. The angles so obtained during grinding were accurately measured by protectors. For fine results the
blank on which experiments were conducted was initially machined (turned) by very small depth of cut by other cutting
tools. Stop watch was used to determine the tool life.
Machining parameters used in experiments:
Machining parameters like depth of cut, nose radius of cutting tool, speed (rpm) of machine, feed rate, relief (both side
and end relief) angle of tool, end cutting edge angle and side cutting edge angle all were kept constant. The only
parameter that has been altered was effective rake angle. The rpm (rotations per minute) of machine was determined by
digital tachometer. The table I shows the machining parameters:
Table I: Parameters during turning operation.
Sr.
No.
RAKE
ANGLE(α)
WEDGE
ANGLE(γ)
RELIEF
ANGLE(β)
FEED
RATE
(MM/REV.
)
DEPTH
OF
CUT(MM)
SPEE
D (RPM)
1
265
1
0.5
2
265
1
0.5
3
265
1
0.5
4
265
1
0.5
5. RESULTS AND DISCUSSIONS
Based on the observations recorded, the experimental results are shown in table II:
Table II: Effect of rake angle on tool life and volume of material removed.
VOUME
WEDG
OF
RAKE
RELIEF
TOOL
Sr.
E
MATERIA
ANGLE(α
ANGLE(β
LIFE
No.
ANGLE(γ
L
)
)
(minutes)
)
REMOVED
(
)
1
267256.12
122.24
2
257075.61
86.93
3
190216.70
62.52
4
317368.11
170.69
Figure I & II represents the effect of rake angle on tool life and volume of material removed.
175
TOOL LIFE (MINUTES)
150
125
100
75
50
0
2
4
6
RAKE ANGLE (DEGREES)
Figure I: Effect of rake angle on tool life.
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3
VOLUME OF MATERIAL REMOVED (mm )
350000
300000
250000
200000
150000
100000
50000
0
2
4
6
RAKE ANGLE (DEGREES)
Figure II: Material being removed during cutting.
The volume of material removed is given by the relation:
= ( - )xL
Where:
= Volume of material removed in
R = Initial radius in mm.
r = Final radius in mm.
L= Length of cut in mm.
.
From the above obtained data and figure it is found that the rake angle of
gave the longest tool life of 170.69 minutes
and the volume of material that has been removed during this period is 317368.11
. Time and energy are very
important parameters used in optimizing the production capacity of any production unit, selection of the best rake angle
for turning is pretty much important. Hence both useful production time and energy is saved. It may be concluded that
choosing
rake angle, gives maximum tool life other than,
and 3 degrees.
Acknowledgement:
We would like to express our gratitude to thank all friends for their technical support, valuable discussions and assistance,
in the project.
References:
[1.] Milton C. Shaw, Metal cutting principles, Oxford University Press, Inc. New York, 2010.
[2.] Sumit Kanti Sikdar, Mingyuan Chen, “Relationship between tool flank wear area and component forces in single
point turning” Journal of Materials Processing Technology 128,pp.210–215, 2002.
[3.] J. Wang, C.Z. Huang1, W.G. Song, “The effect of tool flank wear on the orthogonal cutting process and its practical
implications” Journal of Materials Processing Technology 142,pp. 338–346, 2003.
[4.] Yung-Chang Yen, Jörg Söhner , Blaine Lilly, Taylan Altan,” Estimation of tool wear in orthogonal cutting Using the
finite element analysis” Journal of Materials Processing Technology 146,pp. 82–91, 2004.
[5.] Mustafa Gunay, Ihsan Korkut, Ersan Aslan, Ulvi Seker, “Experimental investigation of the effect of cutting tool rake
angle on main cutting force” Journal of Materials Processing Technology 166 ,pp. 44–49, 2005.
[6.] S.N. Huang, K.K. Tan, Y.S. Wong, C.W. de Silva, H.L. Goh, W.W. Tan,” Tool wear detection and fault diagnosis
based on cutting force Monitoring” International Journal of Machine Tools & Manufacture 47,pp. 444–451, 2007.
[7.] Zydrunas Vagnorius, Marvin Rausand, Knut Sorby,” Determining optimal replacement time for metal cutting tools”
European Journal of Operational Research 206,pp. 407–416,2010.
[8.] Kumar Sambhav, Abhishek Kumar, Sounak K.Choudhury,” Mechanistic force modeling of single point cutting tool
in terms of grinding angles” International Journal of Machine Tools & Manufacture 51,pp. 775–786, 2011.
[9.] Bala´ zs Tukora, TiborSzalay,” Real-time determination of cutting force coefficients without cutting geometry
restriction” International Journal of Machine Tools & Manufacture 51,pp. 871–879, 2011.
[10.] Engr. Kaisan Muhammad Usman, “Effects of Tool Rake Angle on Tool Life in Turning Tools” International Journal
of Scientific & Engineering Research Volume 3,pp. 2229-5518,2012.
Volume 2, Issue 11, November 2013
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