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Indian Journal of Engineering & Materials Sciences
Vol. 21, April 2014, pp. 139-148
Experimental investigation of cutting zone temperature and flank wear correlation
in turning AISI 1045 steel with different tool geometries
N Senthilkumara* & T Tamizharasan
b
aAdhiparasakthi Engineering College, Melmaruvathur 603 319, India bTRP Engineering College, Irungalur, Tiruchirappalli 621 105, India
Received 22 November 2012; accepted 1 November 2013
This paper focuses on the experimental investigation and analysis of temperature generated at the cutting zone during
machining and the wear of cutting insert at the flank face and the relationship between these parameters. Uncoated cemented
carbide inserts of different geometries are used to turn AISI 1045 steel. Three levels of cutting insert geometries cutting
insert shape (included angle), relief angle and nose radius are chosen. Taguchi’s design of experiments (DoE) is used to
design the experiments and using signal-to-noise (S/N) ratio, the control parameters are analyzed, showing a correlation
between the two responses. Analysis of variance is performed to determine the most significant factor over the responses
and empirical models are developed for predicting the responses using multiple linear regression models. Cutting zone
temperature is mostly influenced by nose radius followed by cutting insert shape and for flank wear the significance of
cutting insert shape is more, followed by nose radius. Confirmation experiment performed with optimum cutting insert
geometry shows a reduction in cutting zone temperature and flank wear.
Keywords: Cutting zone temperature, Flank wear, Taguchi’s technique, ANOVA
Machining is the term used to describe removal of
material from the workpiece, and cutting generally
involves single-point or multipoint cutting tools with a
clearly defined tool shape. The cutting tool is set at a
certain depth of cut and travels to the left with a certain
velocity called as feed rate, which is the distance the
tool travels per unit revolution of the workpiece as the
workpiece rotates at certain cutting speed to remove the
material as chip which moves up the face of the cutting
tool1. The schematic diagram of the orthogonal cutting
process is shown in Fig. 1, in which a cutting tool
moves to the left along the workpiece at a constant
velocity V and depth of cut to. A chip is produced ahead
of the tool by deforming and shearing the material
continuously along the shear plane1.
The geometry of cutting tools affects the quality and
productivity of machining operations, chip control,
magnitude, and direction of the cutting force and its
components. For a given combination of the tool and
work materials, there is the cutting temperature,
referred to as the optimal cutting temperature at which
the combination of minimum tool wear rate, minimum
stabilized cutting force, and highest quality of the
machined surface, is achieved2.
The cutting edge is formed by the intersection of the
rake face with the clearance face or flank of the tool.
The tool is so designed and held in such a position that
the clearance face does not rub against the freshly cut
metal surface. The nose of the tool is at the intersection
of all three faces and may be sharp, but more
frequently there is a nose radius between the two
clearance faces3. The various shapes of cutting tool
inserts used for machining AISI 1045 steel in this work
is shown in Fig. 2.
In this study, nine ISO designated uncoated carbide
cutting tool inserts having different geometries4,5
such
as shape of the cutting insert (included angle of the
tool), relief angle and nose radius are chosen for
analysis. The machining parameters cutting speed, feed
—————
*Corresponding author (E-mail: [email protected])
Fig. 1—Schematic illustration of orthogonal cutting
INDIAN J ENG. MATER. SCI., APRIL 2014
140
rate and depth of cut are kept constant. The
correlation between cutting zone temperature and
flank wear are studied to determine the influence of
one response over another response. This analysis is
essential since the output quality characteristics
depends on the geometry of the cutting tool and
machining parameters selected6,7
. The stability of the
cutting tool will be decided by the geometries chosen.
Tamizhmanii and Hasan8 evaluated the relationship
between flank wear on CBN and PCBN tool and
cutting forces during machining AISI 440C martensitic
stainless steel and observed that the greater the values
of flank wear, the higher friction of tool on the work
material and higher heat generation occurs. Akhyar et
al.9 optimized the cutting parameters in turning Ti-6%
Al-4%V alloy steel with coated and uncoated carbide
tools under dry condition and high cutting speed using
Taguchi method. Motorcu10
optimized machining
parameters and tool’s nose radius using Taguchi
method over surface roughness while turning AISI
8660 steel with ceramic tool and developed a second
order regression model for prediction. Ramanujam et
al.11
investigated the effect of machining parameters in
turning Al-Sic MMC using PCD insert and optimized it
using grey relational analysis over specific power and
surface finish. Kaladhar et al.12
optimized multiple
responses surface roughness and MRR while turning
AISI 202 austenitic stainless steel with coated carbide
tool and further confirmed it by calculating the
confidence interval.
Problem Identification
Cutting tools are subjected to high localized
stresses, high temperatures, sliding of the chip along
the rake face and sliding of the tool along the freshly
cut surface during metal removal process. These
conditions induce tool wear which in turn adversely
affects tool life, quality of the machined surface and
its dimensional accuracy and consequently the
economics of cutting operations. The rate of tool wear
depends on tool and workpiece materials, tool shape,
cutting fluids, machining parameters and machine-
tool characteristics.
The mechanical energy consumed in the cutting area
is converted into heat. The main sources of heat are the
shear zone, the interface between the tool and the chip
where the friction force generates heat; and the lower
portion of the tool tip, which rubs against the machined
surface. The interaction of these heat sources,
combined with the geometry of the cutting area results
in a complex temperature distribution. The temperature
generated in the shear plane is a function of the shear
energy and the specific heat of the material. Increase of
temperature on the tool face depends on the friction
conditions at the interface. Temperature distribution
will be a function of many other factors such as the
thermal conductivities of the workpiece, the tool
materials, the specific heat, cutting speed, depth of cut,
and the use of a cutting fluid. As cutting speed
increases, there is little time for the heat to be dissipated
away from the cutting area and so the proportion of the
heat carried away by the chip increases. If the tool is dull
or worn, heat is also generated when the tool tip rubs
against the machined surface.
Cutting insert shape (included angle) is considered
since the sharpness of the cutting edge has an effect
on flank wear and surface roughness. Relative edge
strength of the cutting inserts increases with increase
in the included angle and the tendency for chipping
and breaking of inserts with various shapes increases
with decrease in included angle of the cutting tool
inserts, which is given in Fig. 3. Strength refers to the
cutting edge shown by the included angle of the
cutting tool inserts1.
Fig. 2—Various shapes of cutting tool inserts for machining
Fig. 3—Edge strength for various cutting inserts
SENTHILKUMAR & TAMIZHARASAN: FLANK WEAR IN TURNING AISI 1045 STEEL
141
Rubbing of flank face of the cutting tool is avoided
by providing relief angle, thereby reducing surface
roughness. It is observed that if the relief angle is
increased, the volume of wear required to reach a
particular width of flank wear land is also increased.
On the other hand, with large relief angles the
mechanical strength of the cutting edge is low and the
tool is more liable to chipping or fracture. The tool
wear is less at the optimum relief angle. Nose radius
of cutting tool is responsible for larger area of contact,
which removes more material from workpiece. Larger
nose radius gives better surface finish. On the other
hand, reducing the nose to a point may make the
surface finish unacceptable. Increasing the nose radius
also decreases the tool wear so that higher cutting
speed can be employed. When the nose radius is
increased excessively, cutting forces and possibility of
chatter increases.
The cause and effect diagram of turning process
involving various input control parameters such as
cutting tool insert shape, relief angle and nose radius
which have an impact on the output responses flank
wear and cutting zone temperature is shown in Fig. 4.
Experimental Procedure
Material selection
The workpiece material chosen for the experimental
investigation of cutting insert geometries is AISI 1045,
medium carbon steel. AISI 1045 is a low cost alloy
with adequate strength and toughness suitable for most
of the engineering and construction applications, whose
Brinell hardness value is 181 BHN. Engineering
applications of AISI 1045 steel includes shafts, pins,
bolts, gears, forgings, cold drawing and extrusion.
Table 1 shows the chemical composition of the chosen
AISI 1045 workpiece material.
The material for cutting insert used for analysis is
uncoated cemented carbide, WIDIA make – THM
grade of Brinell hardness value of 1433 BHN, whose
chemical composition is given in Table. 2.
The SEM photo-micrograph of the cemented
carbide tool is as shown in Figure 5. The micrograph
shows the particles of predominant Tungsten carbide.
Some voids are present during compacting. The
structure is variable composition of solid solution
phases of WC and TiC. The black areas are voids.
The areas in between the grains are cobalt solid
solution. The marginal dendritic solid solution of
cobalt is seen at the extreme right.
Experimental set-up and methodology
The experiments are conducted on a CNC Turning
center, Lokesh make 2 axis CNC TL-20, swing
Table 1—Chemical composition of AISI 1045 Steel
Sl. No Elements Alloying %
1 Carbon(C) 0.312
2 Silicon(Si) 0.189
3 Manganese(Mn) 0.852
4 Chromium(Cr) 0.025
5 Molybdenum(Mo) 0.033
6 Titanium(Ti) 0.005
7 Vanadium(V) 0.004
8 Tungsten(W) 0.033
9 Phosphorous(P) 0.039
10 Sulphur(S) 0.011
11 Copper(Cu) 0.031
12 Aluminium(Al) 0.037
13 Iron 98.429
Fig. 4—Cause and effect diagram of problem statement
Table 2—Chemical compositions of cutting tool insert
Sl. No Elements/compound Alloying %
1 Tungsten carbide 96.4
2 Titanium carbide 0.5
3 Tantalum carbide 0.8
4 Cobalt 2.19
Fig. 5—SEM image of cemented carbide cutting insert
INDIAN J ENG. MATER. SCI., APRIL 2014
142
diameter 350 mm, between centre 600 mm, spindle
speed 4500 rpm, main motor power of 11 kW. After
performing the machining process, the flank wear is
measured and recorded by using a Mitutoyo digital
tool makers microscope of specifications, eyepiece
15X, view field diameter 13 mm, objective 2X,
working distance 67 mm, total magnification 30X.
Cutting zone temperature is measured using
METRAVI MT-9 make compact IR thermometer
with dual laser targeting with specifications of IR
temperature range of -50°C to 1000°C, operating
temperature of 0 to 50°C, response time of 150 ms.
Infrared pyrometers allow users to measure
temperature where conventional sensors cannot be
employed in specific applications when dealing with
moving objects or where non-contact measurements
are required. IR thermometer is chosen since it has
quick response, versatility, portability and non-
invasiveness but has the disadvantages of difficulty in
determining the infrared detection area where
accuracy is needed, can only record surface
temperatures and inability to measure very minute
targets13-15
. The experimental setup used to determine
the cutting zone temperature is shown in Fig. 6. The
cutting tool holder with cutting insert is kept upside
down so that the chip generated during the cutting
process will flow downwards thereby exposing the
zone for measuring the temperature at the cutting
zone. The IR thermometer is positioned on the turret
head of the CNC turning center using a stand clamped
to it, thereby continuous measurement of cutting zone
temperature is possible with at most accuracy. The
cutting length of the workpiece, 300 mm is kept
constant throughout the experiment for all conditions,
so that the variation in flank wear can be well
analyzed.
Taguchi technique
Taguchi technique is a powerful tool in quality
optimization16
. Taguchi technique makes use of a special
design of orthogonal array (OA) to examine the quality
characteristics through a minimal number of
experiments. The experimental results based on the
orthogonal array are transformed into S/N ratios to
evaluate the performance characteristics17
. Taguchi’s
DoE is used to design the orthogonal array for three
parameters varied through three levels. The control
parameters and their levels chosen are shown in Table 3.
The machining parameters18
chosen are, cutting
speed as 285 m/min, feed rate as 0.203 mm/rev and
depth of cut as 0.3 mm19
which are kept constant for
all experiments. Figure 7 shows the nomenclature of
Table 3—Control parameters and their levels
Parameter / Level Symbol Level 1 Level 2 Level 3
Cutting insert shape A C (80°) D (55°) S (90°)
Relief angle (°) B 0 3 7
Nose radius (mm) C 0.4 0.8 1.2
Fig. 6—Experimental setup with position of IR thermometer
Fig. 7—Nomenclature of cutting tool inserts used
SENTHILKUMAR & TAMIZHARASAN: FLANK WEAR IN TURNING AISI 1045 STEEL
143
the different cutting tool insert used with various
shapes, relief angles and nose radius. As per ISO
nomenclature, ‘C’ shape inserts are rhombic inserts
which have 80° included angle, whereas ‘D’ shape
inserts have 55° included angle. ‘S’ shape inserts are
square inserts with an included angle of 90°.
The various combinations of cutting insert shapes,
relief angle and nose radius, based on which the
experiments are conducted is presented in Table 4.
For analysis, there are three categories of
performance characteristics, i.e., smaller-the-better
(Eq. 1), larger-the-better (Eq. 2) and nominal-the-
better (Eq. 3). For smaller-the-better category, the
quality characteristics are usually an undesired output
and for larger-the-better category, the quality
characteristics are usually a desired output and for
nominal-the-best category, the quality characteristics
are usually a nominal output.
Smaller-the-better (minimize):
1
1 2/ 10logn
i
S N yin =
= −
∑ … (1)
Larger-the-better (maximize):
1
1 1/ 10log
2
n
i
S Nn y
i=
= −
∑ … (2)
Nominal-the-best:
2/ 10 log
y
yS N
s
=
… (3)
where yi represents the experimentally observed value
of ith experiment and n is the number of replications
of each experiment. To reduce the value of the quality
characteristics to the smallest possible value zero,
which is the ideal or target value, e.g., flank wear,
surface roughness, cutting forces, etc, smaller-the-
better condition is used. When the values of quality
characteristics as much as possible for responses such
as MRR, tool life and productivity are to be increased,
larger-the-better concept is used. When an ideal or
target value is specified to quality characteristics such
as dimensional tolerances, clearance, etc. are needed;
nominal-the-best condition is applied.
Analysis of variance
For analyzing the effect of categorical factors on a
response is determined by performing an analysis of
variance (ANOVA)20,21
. An ANOVA is a statistical
tool, which decomposes the variability in the response
variable amongst the different factors. Depending on
the type of analysis, it may be important to determine
which factors have a significant effect on the
response, and how much of the variability in the
response variable is attributable to each factor. Using
Minitab-16, statistical software ANOVA is
performed.
Multiple linear regression models
Regression is conceptually simple technique for
investigating functional relationship between output
and input decision variables of a process and may be
useful for manufacturing process data description,
parameter estimation and control22
. The criteria for
fitting the best line through the data in simple linear
regression is to minimize the sum of squares of
residuals (Sr) between the measured values of
response and the values of response calculated with
the regression model. The linear fit is expressed as:
0 1y a a x= + … (4)
where y is the value of response and x is the value of
variable. Multiple linear regressions are the useful
extension of the linear regression when the response
is a linear function of two or more independent
variables, which is the case in many practical
applications. In general, the response variable y may
be related to k regressor variables. The model in Eq.
(5) are called a multiple linear regression model with
k regressor variables.
0 1 1 2 2 ...k k
y x x xβ β β β ε= + + + + + … (5)
The parameters βj, j = 0, 1, . , k, are called the
regression coefficients.
Table 4—L9 orthogonal array
Trial
No
Cutting
Insert Shape
Relief
Angle (°)
Nose Radius
(mm)
ISO Insert
Designation
1 C 0 0.4 CNMG 12 04 04
2 C 3 0.8 CAMG 12 04 08
3 C 7 1.2 CCMG 12 04 12
4 D 0 0.8 DNMG 15 04 08
5 D 3 1.2 DAMG 15 04 12
6 D 7 0.4 DCMG 15 04 04
7 S 0 1.2 SNMG 12 04 12
8 S 3 0.4 SAMG 12 04 04
9 S 7 0.8 SCMG 12 04 08
INDIAN J ENG. MATER. SCI., APRIL 2014
144
Results and Discussion The output quality characteristics cutting zone
temperature23-25
is measured during the process of
turning using IR thermometer and flank wear26,27
is
measured after performing the turning operation using
Tool maker’s microscope. Table 5 shows the
measured output responses and their corresponding
S/N ratio, calculated using smaller-the-better given in
Eq. (1), since the cutting zone temperature and flank
wear has to be minimized28
.
From the results obtained from the experiments, it
is observed that when the cutting insert shape is
changed from ‘C’ to ‘D’, a decrease in flank wear by
61.38% and cutting zone temperature by 22.71% is
noticed, which is due to the reduction in included
angle of the cutting tool insert. Changing the insert
shape from ‘D’ to ‘S’ increases the flank wear and
cutting zone temperature by 183.61% and 14.60% due
to the higher contact area of tool due to higher
included angle.
A reduction in flank wear by 11.19% and cutting
zone temperature by 10.61% is observed when a relief
angle of 3° is provided to the cutting insert from
neutral relief which is because of the elimination of
cutting inserts rubbing the workpiece surface. With
further increase in relief angle from 3° to 7°, flank
wear increases by 166.93% and cutting zone
temperature increases by 14.75% due to the sharp
cutting edge provided by higher relief angle.
Flank wear and cutting zone temperature increases
with increase in nose radius. 134.62% and 34.65%
increase in flank wear and cutting zone temperature is
observed when nose radius is changed from 0.4 to 0.8
mm. When nose radius is further changed to 1.2 mm,
flank wear and cutting zone temperature increase by
7.38% and 9.67%, respectively. Increasing the nose
radius increases the contact area of the cutting tool
insert with the workpiece thereby increasing flank
wear and cutting zone temperature.
Analysis of cutting zone temperature
The cutting zone temperature at the tool-workpiece
interface has to be lower during the machining process.
Hence, the smaller-the-better condition is chosen as
given in Eq. (1). The best level of input control
parameters are identified by calculating the average
values of S/N ratio, as given in Table 6.
From the response table of cutting zone temperature,
the optimal parameter levels identified are, cutting
insert shape of ‘D’, relief angle of 3° and nose radius of
0.4 mm. Hence, the optimum condition is represented
as A2B2C1. Figure 8 shows the main effects plot for
cutting zone temperature.
Interaction plot is an effective method to study the
effect of one control parameter over another parameter
over a particular output response29,30
. Figure 9 shows
Table 5—Output quality characteristics and corresponding
S/N ratio
Cutting zone temperature Flank wear Trial
No Experimental
value (°C)
S/N ratio Experimenta
l value (mm)
S/N ratio
1 83.7 -38.4545 0.143 16.893
2 108 -40.6685 0.112 19.016
3 154 -43.7504 0.483 6.321
4 114.7 -41.1913 0.118 18.562
5 84.6 -38.5474 0.134 17.458
6 67.9 -36.6374 0.033 29.630
7 116.4 -41.3191 0.168 15.494
8 88.8 -38.9683 0.136 17.329
9 101 -40.0864 0.502 5.986
Table 6—Response table for cutting zone temperature
Level / Parameter Insert shape Relief angle Nose radius
Level 1 -40.96 -40.32 -38.02
Level 2 -38.79 -39.39 -40.65
Level 3 -40.12 -40.16 -41.21
Max – Min 2.17 0.93 3.19
Fig. 8—Main effects plot for cutting zone temperature
Fig. 9—Interaction plot for cutting zone temperature
SENTHILKUMAR & TAMIZHARASAN: FLANK WEAR IN TURNING AISI 1045 STEEL
145
the interaction effect of input control parameters on
cutting zone temperature. No significant interaction is
observed between cutting insert shape and relief angle
except for ‘C’ shape. The cutting zone temperature is
lower for ‘D’ shape. Significant effect is observed
between cutting insert shape and nose radius for all
the three insert shapes. In between relief angle and
nose radius, no significant effect is seen except for 7°
relief angle. Higher cutting zone temperature is
noticed for higher relief angle, due to the lower
contact area of cutting edge.
To determine the control parameter that has a
significant effect on cutting zone temperature,
ANOVA is performed and the results are given in
Table 7. From the ANOVA table it is evident that the
nose radius of the cutting insert is the most critical
control parameter contributing significantly by
50.29%, followed by cutting insert shape by 20.74%
and whereas the contribution of relief angle is
negligible.
Multiple linear regression models are developed in
order to predict the output responses for a given set of
input control parameters. Minitab-16, statistical
software is used for developing the linear regression
models. The advantage of developing these models is
to determine the value of the output responses for a
given set of input parameters without performing the
experiments. The developed empirical model to
predict the temperature that prevails at the cutting
zone is given in Eqs (6)-(8) for different insert shapes.
For ‘C’ Shape:
Cutting Zone Temperature = 75.194 + 0.551802*
Relief angle
+ 47.75* Nose radius … (6)
For ‘D’ Shape:
Cutting Zone Temperature = 49.0273 + 0.551802*
Relief angle
+ 47.75* Nose radius … (7)
For ‘S’ Shape:
Cutting Zone Temperature = 62.0273 + 0.551802*
Relief angle
+ 47.75* Nose radius … (8)
The residual plots of cutting zone temperature
obtained during generating the empirical model using
regression analysis for geometrical parameters of
cutting tool inserts chosen is shown in Fig. 10. The
normal probability plot of the residuals follows a
straight line in which all the points are very nearer to
the straight line and points are distributed evenly on
both sides of the straight line. In residual versus fits
plot, the residuals appear to be randomly scattered
around zero. No evidence of non-constant variance,
missing terms, outliers, or influential points exists.
The histogram of the residuals shows the distribution
of the residuals for all observations of cutting zone
temperature, which is skewed towards left side.
Residuals versus order graph plot shows that the
residual is higher for observation order 4 and for
majority of the observations, the residual values are
below the zero line.
Analysis of flank wear
For a given value of input control parameters, the
flank wear at the cutting edge of the insert has to be
lower. Hence, the smaller-the-better condition is
chosen as given in Eq. (1). The best level of various
parameters are identified by calculating the average
values of S/N ratio, corresponding to all level of
parameters and are given in Table 8.
Table 7—ANOVA table for cutting zone temperature
Source DOF Seq SS Adj MS F P % Contribution
Insert shape 2 7.161 3.5803 0.84 0.544 20.74
Relief angle 2 1.469 0.7343 0.17 0.853 4.25
Nose radius 2 17.368 8.6840 2.03 0.330 50.29
Residual
error
2 8.536 4.2681 24.72
Total 8 34.533
Fig. 10—Residual plot of cutting zone temperature during
regression modeling
Table 8—Response table for flank wear
Level / Parameter Insert shape Relief angle Nose radius
Level 1 14.08 16.98 21.28
Level 2 21.88 17.93 14.52
Level 3 12.94 13.98 13.09
Max – Min 8.95 3.96 8.19
INDIAN J ENG. MATER. SCI., APRIL 2014
146
From the response table of flank wear, the optimal
parameter level are identified as, cutting insert shape
of ‘D’, relief angle of 3° and nose radius of 0.4 mm.
Hence, the optimum condition is represented as
A2B2C1. From the response table of flank wear, the
main effects plot is drawn as shown in Fig. 11.
The interaction effect of input parameters over
flank wear is shown in Fig. 12. There is no significant
interaction effect between insert shape and relief
angle except for ‘D’ shape insert. The interaction
effect is larger between insert shape and nose radius,
and for higher included angle of insert, the flank wear
is more, which is due to the large area of contact. In
between relief angle and nose radius, there is no
significant interaction effect except for 7° relief angle,
due to higher flank wear.
From the ANOVA results shown in Table 9, it is
evident that the cutting insert shape is the critical
control parameter, which contributes 35.61%,
followed by nose radius by 28.76%, whereas the
contribution of relief angle is negligible.
The empirical model developed to predict the flank
wear at the cutting edge of the carbide cutting tool
inserts is given in Eqs (9)(-(11) for different inserts.
For ‘C’ Shape:
-Flank Wear = 0.00965465 0.0293964*+
Re lief angle
0.197083* Nose radius+ … (9)
For ‘D’ Shape:
Flank Wear = - 0.160655 0.0293964*+
Re lief angle
0.197083* Nose radius+ … (10)
For ‘S’ Shape:
0.013012 0.0293964*Flank Wear = +
Re lief angle
0.197083* Nose radius+ … (11)
The residual plot of flank wear obtained during
regression analysis when geometrical parameters
alone are considered is shown in Fig. 13. The normal
probability plot of the residuals follows a straight line
with the residuals situated nearer to the straight line.
In residual versus fits plot, the residuals appear to be
randomly scattered around zero and most of the points
are situated at the average fitted value and the
residuals are minimum. The histogram of the
residuals shows the distribution of the residuals for all
observations which are skewed towards left and the
bell shaped curve is not obtained. Residuals versus
order graph plot can be particularly helpful in a
designed experiment in which the runs are not
Fig. 11—Main effects plot for flank wear
Fig. 12—Interaction plot for flank wear
Table 9—ANOVA table for flank wear
Source DOF Seq SS Adj MS F P % Contribution
Insert shape 2 142.29 71.15 1.22 0.451 35.61
Relief angle 2 25.57 12.79 0.22 0.820 6.40
Nose radius 2 114.91 57.45 0.98 0.504 28.76
Residual error 2 116.76 58.38 29.22
Total 8 399.54
Fig. 13—Residual plot of flank wear during regression modeling
SENTHILKUMAR & TAMIZHARASAN: FLANK WEAR IN TURNING AISI 1045 STEEL
147
randomized. The residuals in the plot are scattered
around the center line and for majority of the residuals
lie below the center line.
The comparison of experimental and predicted
values of cutting zone temperature and flank wear is
shown in Fig. 14. It is observed from the results that a
moderate prediction is possible with these models.
Confirmation experiment for optimum cutting insert geometry
With the identified optimum values of input control
parameters determined an experiment is conducted to
confirm and validate the effectiveness of the cutting
tool by using the same experimental setup. The
quality characteristics values obtained from the
confirmation experiment are given in Table 10, which
shows that the values obtained are considerably better
than that of experimental results obtained for the
various combinations of input parameters. It is
observed that a reduction in flank wear by 54.68%
and cutting zone temperature by 23.33% is achieved
during machining AISI 1045 steel with the
determined optimum cutting insert geometry.
Correlation of flank wear and cutting zone temperature
The relationship between the cutting zone
temperature at the workpiece-tool interface and flank
wear at the cutting edge of the cutting insert31
is
determined, based on the experimental results. It is
observed that, when the cutting zone temperature
increases, the flank wear increases comparably.
Figure 15 shows the 3D mesh plot showing the
correlation between the cutting zone temperature and
flank wear. This correlation effect between flank wear
and cutting zone temperature is important since
increase in cutting zone temperature has a direct
effect on the wear at the flank face of the cutting
Fig. 14—Comparison of experimental and predicted responses
Table 10—Results of confirmation experiment
Optimum condition Confirmation results
Cutting
insert
shape
Relief
angle (°)
Nose
radius (mm)
Flank wear
(mm)
Cutting zone
temperature (°C)
D 3 0.4 0.092 78.3
Fig. 15—Correlation plot between cutting zone temperautre and
flank wear
INDIAN J ENG. MATER. SCI., APRIL 2014
148
insert. The flank wear increases the surface roughness
of the machined surface of the specimen. Hence, by
improving the geometry of the cutting insert, the
cutting zone temperature and the flank wear can be
controlled, producing quality products at lower rates.
Conclusions The following conclusions have been derived by
applying Taguchi technique on turning AISI 1045
steel with different cutting tool insert geometries to
determine the relationship between cutting zone
temperature and flank wear.
(i) The optimum tool geometries for lower cutting
zone temperature and flank wear is cutting insert
shape of ‘D’ (55° included angle), relief angle of
3° and nose radius of 0.4 mm.
(ii) From these optimum conditions obtained it is
observed that a considerable correlation exists
between cutting zone temperature and flank
wear, which is also exposed from the 3D mesh
plot between them.
(iii) Nose radius is the most significant parameter for
cutting zone temperature followed by cutting
insert shape and for flank wear, the contribution
of cutting insert shape is more followed by nose
radius.
(iv) Machining with optimum cutting insert
geometry shows a reduction in flank wear by
54.68% and cutting zone temperature by
23.33%.
(v) An indirect estimate of flank wear is possible
on-line by measuring the cutting zone
temperature during machining, which is used to
control the flank wear of the cutting tool insert.
(vi) From the analysis, it is further observed that by
suitably altering the geometry of the cutting
inserts, the performances can be improved.
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