IRJET- The Process of Edm Cutting Parameters Optimizing by using Taguchi Method and Anova on Inconel 718

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 12 | Dec 2018 www.irjet.net p-ISSN: 2395-0072
© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1305
THE PROCESS OF EDM CUTTING PARAMETERS OPTIMIZING BY USING
TAGUCHI METHOD AND ANOVA ON INCONEL 718
M. DHANUNJAYA1, M. MADDULETI2, GOPI CHAND BOOSA3
1Assistant professor in SMSK, DEPT. OF MECHANICAL ENGINEERING,T.S,INDIA.
2Research scholar in SVU, A.P., INDIA
3Assistant professor in SMSK, DEPT. OF MECHANICAL ENGINEERING, T.S, INDIA.
-----------------------------------------------------------------------***------------------------------------------------------------------------
Abstract - Wire Electro - Discharge Machining (EDM) is a
metal-working process whereby material is removed from a
conductive work piece by electrical erosion. This project
work focuses on finding out the optimum parameters in
Wire - EDM for machining of Inconnel 718. The major
application of the Inconnel material is in the aerospace
industry, both in airframes and engine components.
Biocompatibility of Inconnel is excellent, especially when
direct contact with tissue or bone is required.
Input process parameters that are taken into
consideration are wire feed rate, Pulse on time, Pulse off
time, Peak current, and Servo voltage. Output parameters
are Material removal rate (MRR), Kerf width and Surface
roughness (SR) are measured. Also different wire materials
like Half Hard Brass wire, Zn-Coated Brass wires are used in
this experiment.
For design of experiment Taguchi methodology of
L18 orthogonal array is used. From the experiment, it can be
conclude that Zn-Coated Brass wire is desirable for
maximum MRR and minimum SR with good surface
integrity, but Half Hard Brass wire is desirable for minimum
Kerf width. An excellent combination of better flush ability,
high mechanical strength and good electrical conductivity
are the advantages of Zn-Coated Brass wires in contrast to
Half Hard Brass wire.
Key words: wire feed rate, Pulse on time, Pulse off
time, Peak current, and Servo voltage. Material
removal rate (MRR), Kerf width and Surface roughness
(SR).
1. INTRODUCTION
1.1 Electrical Discharge Machining (EDM)
Electrical Discharge Machine (EDM) is now become
the most important accepted technologies in
manufacturing industries since many complex 3D shapes
can be machined using a simple shaped tool electrode.
Electrical discharge machine (EDM) is an important „non-
traditional manufacturing method‟, developed in the late
1940s and has been accepted worldwide as a standard
processing manufacture of forming tools to produce
plastics moldings, die castings, forging dies and etc.
Major development of EDM was observed when computer
numerical control systems were applied for the machine
tool industry. Thus, the EDM process became automatic
and unattended machining method. At the present time,
Electrical discharge machine (EDM) is a widespread
technique used in industry for high precision machining of
all types of conductive materials such as: metals, metallic
alloys, graphite, or even some ceramic materials, of
whatever hardness.
1.2 Wire Electrical Discharge Machining (WEDM)
The world‟s first WEDM was produced by the SWISS
FIRM„ AGIE‟ in 1969. The first WEDM machine worked
simply without any complication and wire choices were
limited to copper and brass only. Several researches were
done on early WEDM to modify its cutting speed and
overall capabilities. In recent decades, many attempts
were done on Wire EDM technology in order to satisfy
various manufacturing requirements, especially in the
precision mold and die industry. Wire EDM efficiency and
productivity have been improved through progress in
different aspects of WEDM such as quality, accuracy, and
precision.
1 .3 Principle of Wire - EDM
The Spark Theory on a wire EDM is basically the
same as that of the vertical EDM process. In wire EDM, the
conductive materials are machined with a series of
electrical discharges (sparks) that are produced between
an accurately positioned moving wire (the electrode) and
the work piece. High frequency pulses of alternating or
direct current is discharged from the wire to the work
piece with a very small spark gap through an insulated
dielectric fluid (water).
Many sparks can be observed at one time. This is
because actual discharges can occur more than one
hundred thousand times per second, with discharge
sparks lasting in the range of 1/1,000,000 of a second or
less. The volume of metal removed during this short

period of spark discharge depends on the desired cutting
speed and the surface finish required. The wire electrode
is usually a spool of brass, copper or brass and zinc wire
from 0.001 to 0.014” thick.
Figure 1.1: Schematic Diagram of WEDM Process [5]
The heat of each electrical spark, estimated at around
15,000° to 21,000° Fahrenheit, erodes away a tiny bit of
material that is vaporized and melted from the work piece
and some of the wire material is also eroded away. These
particles (chips) are flushed away from the cut with a
stream of de-ionized water through the top and bottom
flushing nozzles. The water also prevents heat build-up in
the work piece. Without this cooling, thermal expansion of
the part would affect size and positional accuracy. Wire
EDM removes material with electricity by means of spark
erosion. Therefore, material that must be EDM must be
electrically conductive.
1.4 Advantages of Wire EDM Process
 Mechanical stress is eliminated during machining
since there is not any contact between Wire and work
piece.
 This process is able to produce complicated work
pieces in different shapes and size.
 WEDM process can be applied for repairing damaged
parts.
 A good surface finish can be obtained. Very fine holes
can be easily drilled.
 Any electrical conducting materials can be machined
by WEDM process apart from its hardness, toughness
and brittleness.
1.5 Disadvantages of Wire EDM Process
 High cost is required for wire and machining.
 There is a problem regarding the formation of recast
layer on machined part surface.
 WEDM process shows very slow cutting rate.
 WEDM process is not applicable for machining very
large work piece.
 Potential fire hazard associated with use of
combustible oil based dielectrics.
 Power consumption is high.
2. LITERATURE REVIEW
Literature review provides the scope for the present
study. This chapter will play a part to get the information
about wire cut electrical discharge machine and will give
idea to operate the test and form the early stage of the
projects; various literature studies have been done. This
chapter includes almost the whole operation including the
test, history, machining properties and results. In this
chapter we have included research papers related to
WEDM with effect on Material Removal Rate (MRR), kerf
width, Surface Roughness (SR), work piece material, work
piece thickness and electrode material.
Atul kumar and Dr D.K. Singh [1] have study variation of
cutting performance with pulse on time, pulse off time,
open voltage, feed rate override, wire feed, servo voltage,
wire tension and flushing pressure were experiment
investigated in wire electric discharge machining
processes. Brass wire with 0.25 mm diameter and SKD 61
alloys steel with 10 mm thickness were used as tool and
work materials. The output considered has been MRR and
surface roughness. Experimentation has been competed by
using Taguchi’s L18 (21×37) orthogonal array under
different conditions of parameters. Finally it concluded
that the MRR increases with the increase in pulse on time
and decrease with increase in pulse off time and open
voltage. The effect of feed rate overdrive, wire feed, servo
voltage, wire tension and flushing pressure on MRR is not
very significant. For the surface roughness it decrease with
increase of pulse off time open voltage and wire feed and
increases with increase in feed rate override and servo
voltage. The effect of other parameter is not significant.
2. Pujari Srinivasa Rao, Koona Ramji, Beela
Satyanarayana [2] studied Wire-cut electric discharge
machining of Aluminum-24345. Experimentation has been
done by using Taguchi’s L18 (21x37) orthogonal array

under different conditions of parameters. The response of
surface roughness is considered for improving the
machining efficiency. Optimal combinations of parameters
were obtained by this method. The confirmation
experiment shows, the significant improvement in surface
finish (1.03μm) was obtained with this method. The study
shows that with the minimum number of experiments the
stated problem can be solved when compared to full
factorial design. All the experiments were conducted on
Ultra Cut 843/ ULTRA CUT f2 CNC Wire-cut EDM machine.
3. Kuriachen Basil, Dr. Josephkunju Paul, Dr. Jeoju
M.Issac [3] investigates the effect of voltage, dielectric
pressure, pulse on-time and pulse off-time on spark gap of
Ti6AL4V alloy. It has been found that pulse on time and
pulse off time have the more impact on the spark gap. The
minimum spark gap was obtained as 0.040407mm. The
WEDM experiments were conducted in Electronic Ultracut
S1 machine using 0.25 mm brass wire as the tool electrode.
Pulse on time, pulse off time, voltage and dielectric
pressure are the four WEDM parameters that were
selected for investigations. In this experimental study two
level full factorial experiment is adopted because this gives
all possible combinations of machine parameters. It can be
noticed from that corresponding to minimum value of
pulse off time the spark gap decreases with increase in
dielectric pressure, whereas the spark gap increases with
increase in dielectric pressure corresponding to maximum
value of pulse off time.
3. DESIGN OF EXPERIMENT
3.1 WEDM Process Parameters
The process parameters that can affect the quality of
machining or cutting or drilling in Wire EDM process are
shown through Ishikawa cause – effect diagram as shown
in Figure 3.1.
The major parameters are as follows:-
 Electrical parameters: Peak current, pulse on
time, pulse off time, supply voltage and
polarity.
 Non – electrical parameters: wire speed; work
feed rate, machining time, gain and rate of
flushing.
 Electrode based parameters: Material and size
of wire.
Figure 3.1: Process Parameters and Performance
Measures of WEDM
3.2 Wire Cut Electro Discharge Machine [WEDM]
This experimental work performed at Shubham wire
cut, Odhav, Ahmedabad. The experiment work is carried
out in sprintcut wire cut electro discharge machine
(ELEKTRONICA SPRINTCUT 734) of Inconnel 718 material
by varying machining parameters.
The sprintcut wire cut electric discharge machine is
consist of a machine tool, a power supply unit and
dielectric supply unit. A schematic diagram of the sprintcut
wire cut EDM is shown in Figure 4.1.
.
Figure 3.1: Sprintcut Wire Cut EDM.

Table No 3.1: Final Measurement Data (Half Hard
Brass wire (0.25mm))
Table No 3.2 Results of Zn-Coated Brass wire
(0.25mm)
4. Analysis of Variance (ANOVA)
ANOVA is a standard statistical technique to
interpret the experimental results. The percentage
contribution of various process parameters to the selected
performance characteristic can be estimated by ANOVA.
Thus information about how significant the effect of each
controlled parameter is on the quality characteristic of
interest can be obtained. ANOVAs for raw data has been
performed to identify the significant parameters and to
quantify their effect on the performance characteristic. The
ANOVA based on the raw data identifies the factors which
affect the average response rather than reducing variation.
ANOVA helps in formally testing the significance
of all main factors and their interactions by comparing the
mean square against an estimate of the experimental
errors at specific confidence levels. Study of ANOVA table
for a given analysis helps to determine which of the factors
need control and which do not. Once the optimum
condition is determined, it is usually good practice to run a
confirmation experiment. The analysis of the partial
experiment must include an analysis of confidence that
can be placed in the results. So analysis of variance is used
to provide a measure of confidence.
First the formula finding for the Pure Sum of Square (SS’)
is given below:
SS’= Seq SS – DF * (Adj MS Error)
And the Percentage Contribution formula is given below:
Percentage contribution = (SS’/ Total Seq. SS) * 100%
Percentage contribution of input parameters to outputs
MRR, Kerf width, and Surface Roughness.
4.1 ANOVA for MRR (Half Hard Brass Wire)
In this research work, ANOVA Table for MRR Half Hard
Brass wire (0.25mm) is shown in Table 5.15
Calculation of SS’ and Percentage Contribution of MRR for
Half Hard Brass wire.
1. Pure Sum of Square (SS’) –
For WF SS’:
 36.780 – (1*1.882)
 36.780 – 1.882
 34.898
For Ton SS’:
 514.252 – (2*1.882)
 514.252 – 3.764
 510.488
For Toff SS’:
 106.255 – (2*1.882)
 106.255 – 3.764
 102.491
For Ip SS’:
 16.506 – (2*1.882)
 16.506 – 3.764
 12.742
WF Ton Toff Ip SV MRR KERF SR
No.
(m/mi
n) (µs) (µs)
(Am
p)
(Vol
t)
(mm2/
min) (mm) (µm)
1 6 110 50 120 15 4.878 0.290 2.556
2 6 110 55 140 20 4.95 0.298 2.501
3 6 110 60 160 25 5.00 0.310 2.423
4 6 115 50 120 20 5.347 0.308 2.883
5 6 115 55 140 25 5.543 0.317 3.102
6 6 115 60 160 15 5.917 0.278 3.256
7 6 120 50 140 15 6.493 0.338 3.723
8 6 120 55 160 20 6.600 0.302 3.384
9 6 120 60 120 25 6.711 0.273 2.892
10 8 110 50 160 25 4.44 0.263 2.390
11 8 110 55 120 15 4.71 0.193 2.419
12 8 110 60 140 20 5.181 0.203 2.160
13 8 115 50 140 25 5.68 0.289 2.978
14 8 115 55 160 15 5.91 0.233 3.423

For SV SS’:
 18.993 – (2*1.882)
 18.993 – 3.764
 15.229
TABLE 4.1: MRR Half Hard Brass wire (0.25mm)
2. Percentage Contribution –
For WF Percentage Contribution:
WEDM on Inconnel 718 for Material removal rate for Half
Hard Brass Wire. The percentage contribution of Wire
feed rate is 4.93%, Pulse on time is 72.12%, Pulse off time
is 14.48%, Peak current is 1.80%, Servo voltage is 2.15%,
and error is 4.52%. This error is due to machine
vibration.
3. Percentage Contribution -
=34.898/707.842* 100%
=4.93 %
For Ton Percentage Contribution:
=510.488/707.842* 100%
=72.12 %
For Toff Percentage Contribution:
=102.491/707.842* 100%
=14.48 %
For Ip Percentage Contribution:
=12.742/707.842* 100%
=1.80 %
For SV Percentage Contribution:
=15.229/707.842* 100%
=2.15 %
Above analysis shows the percentage contribution of
individual process input parameters of WEDM on Inconnel
718 for Material removal rate for Half Hard Brass Wire.
The percentage contribution of Wire feed rate is 4.93%,
Pulse on time is 72.12%, Pulse off time is 14.48%, Peak
current is 1.80%, Servo voltage is 2.15%, and error is
4.52%. This error is due to machine vibration.
ANOVA for Kerf Width (Half Hard Brass wire
(0.25mm))
4.2ANOVA Table for Kerf Width for Half Hard Brass
wire (0.25mm)
Percentage Contribution –
=0.013500/0.0340906* 100%
=39.60 %
For Ton Percentage Contribution:
=0.002467/0.0340906* 100%
=7.23 %
For Toff Percentage Contribution:
=0.007938/0.0340906* 100%
=23.29 %
Source DF Seq SS Adj SS Adj MS F P
%
Contrib
ution
WF
(m/min) 1 36.78 36.780 36.78 19.54 0.002 4.93
Ton (µs) 2 514.25 514.25 257.1 136.6 0.000 72.12
Toff (µs) 2 106.25 106.25 53.12 28.23 0.000 14.48
Ip (Amp) 2 16.506 16.506 8.253 4.39 0.052 1.80
Sv (Volt) 2 18.993 18.99 9.497 5.05 0.038 2.15
Error 8 15.056 15.05 1.882 4.52
Total 17 707.84 100
Source DF Seq SS Adj SS Adj MS F P Percentage
Contributio
n
WF
(m/min) 1
0.013
8889
0.0138
889 0.0138889
35.7
4
0.0
00 39.60
Ton (µs) 2
0.003
2444
0.0032
444 0.0016222 4.17
0.0
57 7.23
Toff (µs) 2
0.008
7155
0.0087
155 0.0043578
11.2
1
0.0
05 23.29
Ip (Amp) 2
0.003
2068
0.0032
068 0.0016034 4.13
0.0
59 7.13
Sv (Volt) 2
0.001
9261
0.0019
261 0.0009631 2.48
0.1
45 3.37
Error 8
0.003
1089
0.0031
089 0.0003886 19.38
Total 17
0.034
09 100

For Ip Percentage Contribution:
=0.0024296/0.0340906* 100%
=7.13 %
For SV Percentage Contribution:
=0.0011489/0.0340906* 100%
=3.37 %
718 for Kerf Width for Half Hard Brass Wire. The
percentage contribution of Wire feed rate is 39.60%, Pulse
on time is 7.23%, Pulse off time is 23.29%, Peak current is
7.13%, Servo voltage is 3.37%, and error is 19.38%. This
error is due to machine vibration.
ANOVA for Surface Roughness (Half Hard Brass wire
(0.25mm))
In this research work, ANOVA Table for Surface Roughness
for Half Hard Brass wire (0.25mm) is shown in Table
Table ANOVA for Surface Roughness (Half Hard Brass
wire (0.25mm))
• Percentage Contribution –
– For WF Percentage Contribution:
– 0.04834/3.45549* 100%
– 1.40 %
– For Ton Percentage Contribution:
– 2.45465/3.45549* 100%
– 71.04 %
– For Toff Percentage Contribution:
– 0.22912/3.45549* 100%
– 6.63 %
– For Ip Percentage Contribution:
– 0.31044/3.45549* 100%
– 8.98 %
– For SV Percentage Contribution:
– 0.26353/3.45549* 100%
– 7.63 %
718 for Surface Roughness for Half Hard Brass Wire. The
percentage contribution of Wire feed rate is 1.40%, Pulse
on time is 71.04%, Pulse off time is 6.63%, Peak current is
8.98%, Servo voltage is 7.63%, and error is 4.32%. This
error is due to machine vibration.
5. RESULTS
ANOVA analysis result for the Half Hard Brass wire on
Material Removal Rate, percentage contribution of wire
feed 4.93%, pulse on time is 72.12%, pulse off time
14.48%, peak current is 1.80%, and servo voltage is
2.15%. The optimal level combination factor for MRR in
Half Hard Brass wire is 30m/min for Wire feed, 120 µs for
Pulse on time, 50 µs for Pulse off time, 2Amp for Peak
Current and 20 V for Servo Voltage.
ANOVA analysis result for the Zn-Coated Brass wire on
Material Removal Rate, percentage contribution of wire
feed 2.25%, pulse on time is 75.41%, pulse off time
11.33%, peak current is 3.93%, and servo voltage is
4.88%. For the various parameters show that pulse on
time is the greatest effect on MRR and is followed by pulse
off time, servo voltage, peak current, and wire feed rate in
that order. The optimal level combination factor for MRR
in Zn-Coated Brass wire is 30 m/min for Wire feed, 120 µs
for Pulse on time, 50 µs for Pulse off time, 2 Amp for Peak
Current and 20 V for Servo Voltage.
ANOVA analysis result for the Half Hard Brass wire on
kerf width (Kw), the percentage contribution of wire feed
39.60%, pulse on time is 7.23%, pulse off time 23.29%,
peak current is 7.13%, and servo voltage is 3.37%. For the
wire feed is the greatest effect on kerf width and is
followed by pulse off time, pulse on time, peak current, and
servo voltage in that order. The optimal level combination
factor for kerf width in Half Hard wire is 8m/min for Wire
feed, 110 µs for Pulse on time, 60 µs for Pulse off time, 120
Amp for Peak current and 15 V for Servo Voltage.
Source DF Seq SS Adj SS Adj MS F P
Percent
age
Contrib
ution
WF
(m/min) 1 0.0571 0.0571 0.057 6.50 0.034 1.40
Ton (µs) 2 2.4722 2.4722 1.236 140.69 0.000 71.04
Toff (µs) 2 0.2467 0.2467 0.123 14.04 0.002 6.63
Ip (Amp 2 0.3280 0.3280 0.164 18.67 0.001 8.98
Sv (Volt) 2 0.2811 0.2811 0.140 16.00 0.002 7.63
Error 8 0.0702`2 0.0702 0.008 4.32
Total 17 3.45549 100

ANOVA analysis result for the Zn-Coated Brass wire on
kerf width (Kw), the percentage contribution of wire feed
38.91%, pulse on time is 21.09%, pulse off time 8.35%,
peak current is 11.08%, and servo voltage is 12.22%. For
the wire feed is the greatest effect on kerf width and is
followed by pulse on time, servo voltage, peak current, and
pulse off time in that order. The optimal level combination
factor for kerf width in Zn-Coated Brass wire is 8m/min
for Wire feed, 110 µs for Pulse on time, 60 µs for Pulse off
time, 120 Amp for Peak current and 15 V for Servo Voltage.
6. CONCLUSION
In the presented work, experiments are carried out on
Inconnel 718 work-piece and used two wires like Half
Hard Brass wire (0.25mm) and Zn-Coated Brass wire. The
experiments are carried out for Material Removal Rate
(MRR), Kerf width (Kw) and Surface Roughness with
variables as wire feed, pulse on time, pulse off time, peak
current and servo voltage. There are 18 experimental
readings taken for both Half Hard Brass wire and Zn-
Coated Brass wire for all variables to conduct the
parametric study.
Finally it can be concluded that:
Experimental results show that the increasing the pulse on
time and peak current increasing the material removal
rate (MRR), kerf width, and surface roughness. This is
because the discharge energy increases with pulse on time
and the number of discharges within a given period
becomes more.
From the experiment results pulse on time is the greatest
effect on MRR and surface roughness compare to other
parameters in both the wires. Kerf width is largely affect
by wire feed rate in both the wires.
At higher pulse off time, less number of discharges in a
given time during machining, and results in small MRR,
and Kerf width. Due to less no. of discharge, small craters
on the surface. Hence, surface roughness is getting
minimum. Increasing servo voltage decreases the
discharge energy across the electrodes which results in
reduce MRR.
7. REFERENCES
[1] Atul Kumar and Dr. D. K. Singh, 2012. “Performance
Analysis of Wire Electric Discharge Machining (W-EDM).”
International Journal of Engineering Research &
Technology (IJERT) Vol. 1 Issue 4, June – 2012, ISSN:
2278-0181.
[2] Pujari Srinivasa Rao, Koona Ramji, Beela
Satyanarayana. “Effect of WEDM Conditions on Surface
Roughness: A Parametric Optimization Using Taguchi
Method.” IJAEST, Volume No. 6, Issue No. 1, pp. 041 – 048.
[3] Kuriachen Basil, Dr. Josephkunju Paul, Dr. Jeoju
M.Issac, 2013. “Spark Gap Optimization of WEDM Process
on Ti6Al4V.” ISSN: 2319-5967, ISO 9001:2008 Certified.
International Journal of Engineering Science and
Innovative Technology (IJESIT). Volume 2, Issue 1, January
2013.
[4] Saurav Datta, Siba Sankar Mahapatra. “Modeling
Simulation And Parametric Optimization Of Wire EDM
Process Using Response Surface Methodology Coupled
With Grey-Taguchi Technique.” International Journal of
Engineering, Science and Technology. Vol. 2, No. 5, 2010,
pp. 162-183.
[5] Mustafa I˙lhan Go¨kler, Alp Mithat Ozano¨zgu, 2000.
“Experimental Investigation of Effects Of Cutting
Parameters On Surface Roughness In The WEDM Process.”
International Journal of Machine Tools & Manufacture 40
(2000) 1831–1848.
[6] G.Rajyalakshmi, Dr.P.Venkata Ramaiah. “Simulation,
Modelling and Optimization of Process parameters of Wire
EDM using Taguchi – Grey Relational Analysis”, IJAIR,
ISSN: 2278-7844.
ANOVA for MRR (Half Hard Brass Wire (0.25mm))
In this research work, ANOVA Table for MRR Half Hard
Brass wire (0.25mm) is shown in Table 5.15.
Table 5.15: ANOVA for MRR (Half Hard Brass Wire)

IRJET- The Process of Edm Cutting Parameters Optimizing by using Taguchi Method and Anova on Inconel 718

Recommended

More Related Content

What's hot (17)

Similar to IRJET- The Process of Edm Cutting Parameters Optimizing by using Taguchi Method and Anova on Inconel 718 (20)

More from IRJET Journal (20)

Recently uploaded (20)

IRJET- The Process of Edm Cutting Parameters Optimizing by using Taguchi Method and Anova on Inconel 718