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Process parameters optimization for surface roughness in edm for aisi d2 steel
- 1. INTERNATIONALMechanical Engineering and Technology (IJMET), ISSN 0976 –
International Journal of JOURNAL OF MECHANICAL ENGINEERING
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 1, January - February (2013) © IAEME
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 4, Issue 1, January- February (2013), pp. 203-208 IJMET
© IAEME: www.iaeme.com/ijmet.asp
Journal Impact Factor (2012): 3.8071 (Calculated by GISI)
www.jifactor.com ©IAEME
PROCESS PARAMETERS OPTIMIZATION FOR SURFACE
ROUGHNESS IN EDM FOR AISI D2 STEEL BY RESPONSE SURFACE
METHODOLOGY
1 2 3
P.B.Wagh , R.R.Deshmukh , S.D.Deshmukh
1
(Sr, Lect. COE Osmanabad, prajotwagh71@gmail.com)
2
(Prof. J.N.E.C Aurangabad)
3
(Principal J.N.E.C Aurangabad)
ABSTRACT
In this investigation, response surface methodology (RSM) is used to investigate the
effect of four controllable input variables namely: discharge current, pulse duration, pulse off
time and gape voltage on material removal rate (MRR). A face centred central composite
design matrix is used to conduct the experiments on AISI D2 with copper electrode. The
response is modelled using RSM on experimental data. The significant coefficients are
obtained by performing analysis of variance (ANOVA) at 95% confidence level. It is found
that discharge current and pulse duration are significant factors. RSM is a precision
methodology that needs only 31 experiments to assess the conditions.
Keywords: Electrical discharge machining; EDM; Material removal rate; RSM; etc
1. INTRODUCTION
Electrical Discharge Machining (EDM) is an unconventional manufacturing process
based on removal of material from a part by means of a series of repeated electrical sparks
created by electric pulse generators at short intervals between an electrode tool and the part to
be machined immersed in dielectric fluid. At present, EDM is a widespread technique used in
industry for high precision machining of all types of conductive materials such as metallic
alloys, metals, graphite, composite materials or some ceramic materials. The selection of
optimized manufacturing conditions is one of the most important aspects to consider in the
die sinking electrical discharge machining (EDM) of conductive steel, as these conditions are
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6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 1, January - February (2013) © IAEME
the ones that are to determine such important characteristics: surface roughness, electrodes wear
(EW) and material removal rate (MRR). In this paper, a study will be perform on the influence of
the factors of peak current, pulse on time, interval time and power supply voltage.
2. EXPERIMENTAL WORK
2.1 Experimental Setup
Figure 1. EDM machine
For this experiment the whole work is done by using Electric Discharge Machine, model
ELECTRONICA- ELECTRAPULS PS 50ZNC (die-sinking type), having provision of
programming in the Z-vertical axis and manually operated X and Y axes. The tool is made of
cathode and the work piece as anode. Commercial grade EDM oil (specific gravity= 0.763 kg/
m3), freezing point= 94°C) was used as dielectric fluid with lateral flushing (pressure of 0.3
kgf/cm2) system for effective flushing of machining debris from working gap region.
2.2 selection of work piece
The material AISI D2 (American Iron Steel Institute D2) is high carbon high chromium
non shrinking water hardening die steel material. The selected material is of 20mm diameter and
250mm long. It is cut into pieces of size 20mm diameter and 5mm length for experimentation.
2.2.1Composition of AISI D2 material
Element Composition weight (%)
C 1.5
Mn 0.3
Si 0.3
Cr 12
Ni 0.3
CO 1.00
V 0.8
Fe Remaining
Table 1Composition of AISI D2 material
2.3 selection of tool electrode
A cylindrical shaped pure copper of diameter 12mm is used for machining of AISI D2
material.
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6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 1, January - February (2013) © IAEME
2.4 selections of process parameters
factor/level (coding) -2 -1 0 1 2
Discharge current 2 6 10 14 18
Spark on time 20 40 60 80 100
Spark off time 2 4 6 8 10
Spark gap 0.05 0.0875 0.125 0.1625 0.2
Table 2 levels of process parameters
3. EXPERIMENTAL RESULTS FOR MATERIAL REMOVAL RATE FOR MATERIAL
AISI D2
Run Ip Ton Toff S.G Wjb Wja Machini density
(A) (µs) (µs) (mm) (gm) (gm) ng time (gm/mm3)
(sec)
(mm3/mim)
1 14 80 8 0.0875 16.9 16.33 5 0.0077 14.8050
2 18 60 6 0.125 14.34 13.56 5 0.0077 20.2727
3 14 40 8 0.0875 15.83 15.18 5 0.0077 17.0120
4 14 80 4 0.1625 15.56 14.85 5 0.0077 18.4420
5 10 60 6 0.125 16.61 16.10 5 0.0077 13.1820
6 6 80 8 0.1625 13.9 13.62 5 0.0077 7.3760
7 10 60 6 0.125 16.63 16.21 5 0.0077 11.0380
8 6 40 4 0.1625 19.45 19.08 5 0.0077 9.5840
9 10 60 6 0.125 18.94 18.46 5 0.0077 12.3376
10 6 80 4 0.1625 15.07 14.83 5 0.0077 6.1168
11 10 60 6 0.05 17.25 16.75 5 0.0077 12.9610
12 10 20 6 0.125 16.30 15.71 5 0.0077 15.3120
13 14 40 8 0.1625 15.12 14.45 5 0.0077 17.4280
14 10 60 6 0.125 17.18 16.70 5 0.0077 12.4670
15 10 60 6 0.125 14.81 14.31 5 0.0077 13.1030
16 6 80 8 0.0875 15.73 15.57 5 0.0077 4.1558
17 6 80 4 0.0875 15.27 15.02 5 0.0077 6.5974
18 10 60 6 0.125 15.44 15.02 5 0.0077 11.0380
19 6 40 4 0.0875 15.49 15.25 5 0.0077 6.3640
20 10 100 6 0.125 15.36 15.00 5 0.0077 9.3506
21 14 40 4 0.0875 15.77 15.12 5 0.0077 17.0120
22 10 60 6 0.2 17.33 16.92 5 0.0077 10.6490
23 14 80 4 0.0875 20.34 19.72 5 0.0077 15.9740
24 10 60 6 0.125 14.35 13.91 5 0.0077 11.4280
25 6 40 8 0.1625 14.56 14.31 5 0.0077 6.4200
26 14 80 8 0.1625 16.55 15.93 5 0.0077 16.2200
27 6 40 8 0.0875 16.06 15.86 5 0.0077 5.1940
28 10 60 10 0.125 17.35 16.86 5 0.0077 12.7660
29 14 40 4 0.1625 14.20 13.56 5 0.0077 16.4940
30 2 60 6 0.125 17.61 17.52 5 0.0077 2.2597
31 10 60 2 0.125 15.52 15.02 5 0.0077 13.1298
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Table 3 Experimental results for Material removal rate for Material AISI D2
M a in E ffe c t s P lo t ( d a t a m e a n s ) fo r M R R
Ip T on
20
15
10
5
Mean of MRR
0
2 6 10 14 18 20 40 60 80 100
T off SG
20
15
10
5
0
2 4 6 8 10 0 .0 5 0 0 0 .0 87 5 0 .1 2 5 0 0.1625 0 .2 00 0
Graph 1 Effect of machining parameters on MRR
4 RESPONSE OPTIMIZATION
Response Goal Lower Target
MRR Maximum 0 20.277
Optimal Ip Ton Toff SG
Hi 18.0 100.0 10.0 0.20
D Cur [18.0] [20.0] [2.0] [0.050]
1.0000 Lo 2.0 20.0 2.0 0.050
MRR
Maximum
y = 23.2978
d = 1.0000
Graph 2 D- Optimality plot
From this graph we can predict the optimum values of process parameters
Process parameters units Optimum values
Discharge current (Ip) A 18
Spark on time (Ton) µs 20
Spark off time (Toff) µs 2
Spark gap (SG) mm 0.05
Table 4 optimum values of process parameters
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Confirmation test and their comparison with results
Trial Optimum Ra (µm) Error
No. conditions Experimental Predicted (%)
01 Ip=18 A, Ton =20 µs, Toff = 22.783 23.2978 2.20
2 µs, SG = 0.05mm
02 Ip=18 A, Ton =20 µs, Toff = 22.970 23.2978 1.40
2 µs, SG = 0.05mm
Table 5 Confirmation test and their comparison with results
5. CONCLUSION
The choice of the electrical parameters of the EDM process depends largely on the
material combination of the electrode and the work piece and the EDM manufactures only
supply these parameters for a limited amount of material combinations.
The industrialist can directly use the optimum values so that the material removal rate will be
maximum.
MINITAB software was used for DOE and analysis of the experimental result and the
response was validated experimentally.
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