International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
Optimization of EDM Parameter of High
Carbon-High Chromium Steel (AISI D3) by
using Brass Electrode
Prashant Yadava#1, Avdesh Chandra Dixit*2, jitendra Kumar Verma#3
#1,*2
#3
M.Tech Student, Mechanical Engineering Deptt. Bhabha Institute of Technology, Kanpur Dehat U.P, India
Assistant Professor, Mechanical Engineering Deptt. Bhabha Institute of Technology, Kanpur Dehat U.P, India
Abstract —This study investigates the influence of
EDM parameters on MRR, EWR while machining of
AISI D3 material. The parameters considered are
pulse-on time (Ton), pulse off time (Toff) peak
current (Ip) and fluid pressure. The experiments
were performed on the die-sinking EDM machine
fitted with a brass electrode. The experiments
planned, conducted and analyzed using Taguchi
method. It is found that the MRR is mainly
influenced by (Ip); where as other factors have very
less effect on material removal rate. Electrode wear
rate is mainly influenced by peak current (Ip) and
pulse on time (Ton), fluid pressure has no effect on
electrode wear rate.
Keywords — EDM, MRR, EWR, brass, Taguchi
method.
trends activities in EDM: machining advanced
materials, mirror surface finish using powder
additives, ultrasonic-assisted EDM and control and
automation.
With the above in mind, studies were conducted on
EDM of AISI D3 using brass electrode to determine
the MRR, EWR.
II. MATERIAL PROPERTIES
A. Work piece Properties
The material used for this work was High carbonhigh chromium steel (AISI D3) with density
7.7×100 kg/m3. The material was hardened to a
hardness of 58 HRC. The work material properties
and the photographic view of workpiece are given
below.
TABLE 1
I. INTRODUCTION
Electrical discharge machining (EDM) is a nontraditional concept of machining which has been
widely used to produce dies and moulds. It is also
used for finishing parts for aerospace and
automotive industry and surgical components. This
technique has been developed in the late 1940s
where the process is based on removing material
from a part by means of a series of repeated
electrical discharges between tool called the
electrode and the work piece in the presence of a
dielectric fluid. The electrode is moved toward the
work piece until the gap is small enough so that the
impressed voltage is great enough to ionize the
dielectric. Short duration discharges are generated in
a liquid dielectric gap, which separates tool and
work piece. The material is removed with the
erosive effect of the electrical discharges from tool
and work piece. EDM does not make direct contact
between the electrode and the work piece where it
can eliminate mechanical stresses chatter and
vibration problems during machining. Materials of
any hardness can be cut as long as the material can
conduct electricity. EDM techniques have developed
in many areas. Trends on activities carried out by
researchers depend on the interest of the researchers
and the availability of the technology. In a book
published in 1994, Author has indicated some future
ISSN: 2231-5381
CHEMICAL COMPOSITION OF AISI D3
Element
%
Element
%
C
2.02
Si
0.28
S
0.026
Cr
11.14
P
0.028
V
0.021
Mn
0.59
W
0.07
Fig. 1 HCHC steel used for experiment
B. Electrode (Tool) Properties
The electrode material used for this work was brass.
- Brass is an alloy of copper and zinc. It is generally
contains 60 to 90% copper and 10 to 40% zinc.
Brass is the most widely used copper alloy .it can be
rolled in to sheets, drawn in wires, cast in to moulds.
The chemical composition of electrode and the
photographic view of electrode are given in table.2
and fig.2.and the electrode specification is given
table.3
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International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
TABLE 2
V. EXPERIMENTATION
CHEMICAL COMPOSITION OF THE BRASS ELECTRODE
Cu%
58.8
Zn%
37.2
Pb%
2.7
Sn%
0.5
Fe%
0.9
Ni%
0.16
TABLE 3
BRASS ELECTRODE SPECIFICATION
Specifications
Density
Thermal Conductivity
Melting Point
Electrical Resistivity
Specific Heat Capacity
Value
8490 kg/m3
158 W/m-K
900 0C
4.7x10-8Ω-m
380 J/kg0C
Fig. 2 Brass tool used for experiment
III. MRR AND EWR
Calculation has been made to determine the
performance parameters of EDM process for each
set of experiment the value of performance
parameters has been calculated.
Material removal rate was calculated from weight
difference of work piece and machining time.
MRR =
A. Equipment used in the experiment
In this study the experiment work was down by
Electric
Discharge
Machine,
model
ELECTRONICA- ELECTRA-PULS C 3822 (diesinking type) with servo-head (constant gap) and
negative polarity for workpiece was used to conduct
the experiments. Fig.3. show the photographic view
of EDM machine. EDM oil of (specific gravity =
0.763, freezing point = 94°C) was used as dielectric
fluid, with circular copper and brass tool. EDM has
maximum current capacity 20 amp. It is capable of
machining of hard material component such as high
carbon high chromium, super alloys, ceramics, steels
etc. A copper electrode of diameter 6 mm is used as
electrode and the work piece of high carbon and
high chromium is machined for 20 minutes to record
the readings. Observations are taken in the form of
mass of material removed per min (gram/min) for
both work piece and copper electrode. Mass lost is
measured with accuracy 0.001 milligram fig.1.show
the photographic view of EDM machine. The data
collected in MRR and EWR form is optimized and
analyzed by Taguchi technique.
gm/min
Tool wear rate was calculated from weight
difference of Tool and machining time.
TWR =
gm/min
Where:
Wwb = weight of workpiece before machining.
Wwa = weight of workpiece after machining.
Wtb = weight of tool before machining.
Wta = weight of tool after machining.
T
= machining time
IV. SIGNAL-TO-NOISE RATIOS (S/N RATIO)
In Taguchi method, the term “signal” represents the
desirable value (mean) for the output characteristic
and the term “noise” represents the undesirable
value (S.D) for the output characteristic. Therefore,
the S/N ratio is the ratio of the mean to the S.D. S/N
ratio is used to measure the quality characteristic
deviating from the desired value.
S/N ratio η is defined as
S/N ratio, is taken as the “Larger is Better” so the
equation to find out signal to noise ratio is,
S/N = -10 *log (Σ (1/Y2)/n)
S/N ratio, is taken as the “Smaller is Better” so the
equation to find out signal to noise ratio is,
S/N = -10 *log (Σ (Y2)/n)
ISSN: 2231-5381
Fig. 1 EDM Machine
B. Design of experiment
The main objective of the experimental design is
studying the relations between the response as a
dependent variable and the various parameter levels.
It provides a prospect to study not only the
individual effects of each factor but also their
interactions. The design of experiments for
exploring the influence of various predominant
EDM process parameters as peak current, pulse on
time, pulse off time and fluid pressure on the
machining characteristics such as material removal
rate and tool wear rate was modelled. In the present
work experiments were designed on the basis of
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International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
design of experimental technique using L9
orthogonal array. The coded levels for all process
parameters used are displayed in Table 4. The
experiment was design with 4 factors at 3 levels
each; the fractional factorial design used is L9
orthogonal array. There are 9 trials in the control
factor array and each row of the matrix represents
one trial. This orthogonal array is use due to its
simplicity and versatile for data analysis. The design
of the L9 orthogonal array of EDM is shown in table
5. The selection of level for this experiment is good
since certain unique features. If closely observed, the
levels of various factors are balanced between one
another. This makes the orthogonal arrays a
balanced matrix of levels and factors, without any
interruptions from other factors that will affected the
outcome or response of the experiment. In other
words, the effects of one factors is not confused with
any effects of other levels or factors. Analysis of
variance is a method of partitioning variability into
identifiable sources of variation and the associated
degrees of freedom in an experiment.
TABLE 4
MACHINING PARAMETERS AND THEIR LEVELS
Level
1
6
2
5
1
Control Parameters
Pulse ON time (μs)
Pulse OFF time (μs)
Peak current (A)
Fluid Pressure(kg/cm2)
Level
2
9
5
8
2
Level
3
12
8
11
3
TABLE 5
MACHINING PARAMETERS AND THEIR LEVELS
Exp.No.
1
2
3
4
5
6
7
8
9
Pulse
on
Time
(μs)
1
1
1
2
2
2
3
3
3
Pulse
off
Time
(μs)
1
2
3
1
2
3
1
2
3
Peak
Current
(Amp)
1
2
3
2
3
1
3
1
2
Fluid
Pressure
(kg/cm2)
1
2
3
3
1
2
2
3
1
TABLE 6
OBSERVATION OF MMR & EWR FOR BRASS
ELECTRODE
E Pulse
x
on
p Time
.
N
o (μs)
.
1
6
Pulse
off
Time
Peak
Curr
ent
Flui
d
Pr.
(μs)
Amp
kg/
cm2
2
5
1
ISSN: 2231-5381
MRR
EWR
gm/mi
n
0.01
gm/mi
n
0.03
2
3
4
5
6
7
8
9
6
6
9
9
9
12
12
12
5
8
2
5
8
2
5
8
8
11
8
11
5
11
5
8
2
3
3
1
2
2
3
1
0.015
0.02
0.011
0.0115
0.01
0.011
0.003
0.024
0.0315
0.0485
0.0245
0.0365
0.015
0.009
0.0025
0.0185
VI. RESULTS AND DISCUSSION
E
x
p
.
N
o
.
1
2
3
4
5
6
7
8
9
TABLE 7
OBSERVATION OF S/N RATIO OF MMR & S/N
RATIO OF EWR
Puls Puls Pea
Flui
e on e off
k
d
Tim Tim Cur
S/N
Pr.
S/N
e
e
rent
Ratio
Ratio
for
for MRR
EWR
Am kg/
(μs)
(μs)
p
cm2
6
6
6
9
9
9
12
12
12
2
5
8
2
5
8
2
5
8
5
8
11
8
11
5
11
5
8
1
2
3
3
1
2
2
3
1
-37.4473
-34.3555
-31.6511
-36.9594
-36.1868
-38.5867
-40.1305
-51.3212
-33.6717
30.4576
30.0338
26.2852
32.2167
28.7541
36.4782
40.9151
52.0412
34.6566
TABLE 8
SIGNAL TO NOISE RATIO FOR MRR
Level
1
2
3
DELTA
RANK
Pulse on Pulse off
-34.48
-38.18
-37.24
-40.62
-41.71
-34.64
7.22
5.98
2
3
Current
-42.45
-35.00
-35.99
7.46
1
Fluid
Pressure
-35.77
-37.69
-39.98
4.21
4
TABLE 9
RESPONSE MEAN FOR MRR
Level
1
2
3
DELTA
Pulse on Pulse off
0.02583 0.01592
0.01808 0.01667
0.01133 0.02267
0.01450 0.00675
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Current
0.01175
0.02075
0.01100
0.01100
Fluid
Pressure
0.02175
0.01525
0.01825
0.00650
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International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
TABLE 10
SIGNAL TO NOISE RATIO FOR EWR
Level
1
2
3
DELTA
RANK
Pulse on Pulse off
28.93
34.53
32.48
36.94
42.54
32.47
13.61
4.47
1
4
Current
39.66
32.30
31.98
7.67
2
Fluid
Pressure
31.29
35.81
36.85
5.56
3
TABLE 11
RESPONSE MEAN FOR EWR
Level
1
2
3
DELTA
Pulse on Pulse off
0.03667 0.02117
0.02533 0.02350
0.01000 0.02753
0.02667 0.00617
Current
0.01583
0.02483
0.03133
0.01550
Fluid
Pressure
0.02833
0.01850
0.02517
0.00983
Fig. 4 Main effect plot for mean of SN Ratio of
MRR
Fig. 5 Main effect plot for Mean of Means of MRR
Fig. 6. Main effect plot for mean of SN Ratio of
EWR
Fig. 7 Main effect plot for Mean of Means of EWR
VII.
CONCLUSIONS
The present investigation has been carried out to
assess the effect of process parameters on the MRR
and EWR of AISI D3 steel for EDM. The
experiments were carried out by design of
experiments using number of variables at different
levels. Taguchi technique is used for design and
optimization of the process parameters with the use
of Minitab 17 software in machining processes.
Brass electrode has low melting point, low thermal
conductivity and high resistivity due to this its wear
rapidly.
Optimal setting for MRR in the experiment level is
as
Pulse on Time
= 6 μs
Pulse off Time = 8 μs
Current
= 8Amp
Fluid Pressure
= 1 kg/cm2
Optimal setting for EWR
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 34 Number 3- April 2016
Pulse on Time
= 6 μs
Pulse off Time = 8 μs
Current
= 11Amp
Fluid Pressure
= 1 kg/cm2
[9]
[10]
ACKNOWLEDGMENT
Author is thankful to faculty members of Bhabha
Institute of Technology, Kanpur Dehat. Author is
highly obliged to research advisor for their
motivation during research work.
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Science and Technology: From Theory to Application.
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ISSN: 2231-5381
http://www.ijettjournal.org
Prashant
Yadava
(Main Author) P.G student of
Bhabha
Institute
of
Technology, Kanpur Dehat
(U.P) India. Completed B.tech
in Mechanical Engg.
Avdesh
Chandra
Dixit,
P.G student of Bhabha Institute
of Technology, Kanpur Dehat
(U.P) India. Completed B.tech
in Mechanical Engg.
Jitendra Kumar Verma
(Research Advisor)
Assistant
Professor,
Mechanical Engg. Deptt. of
Bhabha Institute of Technology
Kanpur Dehat (U.P) India
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