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• Corresponing author U Ashok Kumar,E-mail address: [email protected] • Doi: http://dx.doi.org/10.11127/ijammc2018.09.06 Copyright@GRIET Publications. All rightsreserved. 109
Advanced Materials Manufacturing & Characterization Vol. 8 Issue 2 (2018)
Experimental optimisation of process parameters on micro hole machining by Die sinker EDM
1U Ashok Kumar. 2P. Laxminarayana 1Research scholar, Mechanical Engineering Dept., University College of Engineering Osmania University, Hyderabad, Telangana state
. 2Professor, Mechanical Engineering Dept., University College of Engineering Osmania University, Hyderabad, Telangana state.
ABSTRACT
The present work deals with micro hole machining of diameter 0.7mm (700µm) on SS316 materials using Die sinker EDM. The design of experiment plan was done by Taguchi L9 Orthogonal Array where the process parameters are current, Time-On, Time-OFF. The output performance are material removal rate, tool wear rate were examined. Keywords: Micro hole 0.7mm, Die Sinker EDM, Taguchi, MRR, TWR.
Introduction
Many new materials are manufacture by the industrial sectors depending upon the design of materials application, such as steel alloys and super Alloys which have high strength, heat resistance and hardness are very difficult in machining complex shapes of the by conventional methods. So these manufacturing problems are overcome by non-traditional machining processes in which Die Sinker electrical discharge machining applications are more in use.The working principle of EDM the following component Power supply - the machining is mainly done by
the direct current by supply which results as spark between the Tool electrode and work piece
Dielectric fluid used to tool and workpiece Workpiece holder, Tool holder and table Servo control– Used to provide a constant gap
between tool and workpiece.
Fig.1 EDM Process
EXPERIMENT METHODOLOGY Work piece and tool required.
Table 1.SS316 stainless steel has been used as work piece material with electrolytic copper with diameter 0.7mm (700µm) was used as tool electrode. The machining process was carried on Acro EDM Machine with process parameters namely Current, T-on, T-off were investigated in this study.
Table 1. Chemical composition of SS 316 Element %
C 0.08
Ni 12
S 0.03
P 0.045
Cr 17
Fe Balanced
Advanced Materials Manufacturing & Characterization
journal home page: www.ijammc-griet.com
110
Design of Experiment for Machining conditions
for micro holes
The experiment is plan on taguchi L9- orthogonal array where numbers of parameter were taken as 3 i.e. Current, T-
on & T-off with number of levels are 3 are table 3,
and experiment according L9 orthogonal Array are
table in 4.
Table 2.Process parameters and their level for micro hole machining
Table 3: Combination of Control parameters based on Experimental L9 OA
Trail of Experiments
Current Ton Toff
1 0.2 6 4
2 0.2 8 6
3 0.2 10 8
4 0.4 6 6
5 0.4 8 8
6 0.4 10 4
7 0.8 6 8
8 0.8 8 4
9 0.8 10 6
From the design of experiments the final output is
Material Removal rate, Tool wear of micro hole
machining.
RESULTS & DISCUSSIONS
The experimental results, in terms of Material Removal
rate ,Tool wear were obtained after conducting the
micro holes machining on Die sinker EDM by copper
electrode with diameter 0.7 mm (700µm) for all nine
specimens and the application of three parameters are
summarized in Table (). In the latter, the results were
analysed by employing main effects, and the signal-to-
noise ratio (S/N) analyses. Finally, a confirmation test
was carried out to compare the experimental results
with the estimated results
Table 4.Experiments results of micro hole machined
surface of SS316
Trail of Expt
I Ton Toff MRR
mg/min
TWR
mg/min
1 0.2 6 4 1.88667 0.021671
2 0.2 8 6 0.89056 0.022412
3 0.2 10 8 1.10733 0.016220
4 0.4 6 6 1.32352 0.007733
5 0.4 8 8 1.00440 0.016925
6 0.4 10 4 0.99254 0.009761
7 0.8 6 8 4.01551 0.012495
8 0.8 8 4 0.48211 0.018447
9 0.8 10 6 2.72357 0.013816
Effects of MRR
Fig 2.Main effects of S/N ratio for MRR
Parameters Current T-ON T-OFF
Symbols A B C
1
0.2 6
4
2
0.4 8
6
3
0.8 10
8
111
From the fig.2 show the combination of microhole
machining parameters ie A3B1C3
(A3-current 0.8, B1-T.ON 6, C3- T.OFF 8)
Table 5.for Signal to Noise Ratios for MRR
Level Current Ton Toff
1 1.7976 6.6745 0.2961
2 0.8026 2.4352 3.3769
3 4.8135 3.1744 4.3328
Delta 4.0109 9.1096 4.6289
Rank 3 1 2
From table 5 shows the Signal to noise ratio of material
removal rate of micro hole machining and it is The
characteristics of S/N ratio for the experimental results
were taken as Larger the better and smaller the better
and expressed as
S/N = −10 *log(Σ(1/Y2)/n)
S/N = −10 *log(Σ(Y2)/n))
Effects of TWR
Fig.3.Main effects of S/N ratio for TWR
From the fig.3 show the combination of microhole
machining parameters ie A2B1C2
(A2-current 0.4, B1-T.ON 6, C2- T.OFF 6)
Which is not in the taguchi design
Table 6.for Signal to Noise Ratios for TWR
Level Current Ton Toff
1 29.51 31.54 28.78
2 31.29 28.21 30.84
3 30.21 31.27 31.29
Delta 1.78 3.33 2.61
Rank 3 1 2
ANOVA for MRR, TWR for micro hole machining of 0.7 mm
The purpose of ANOVA is to investigate statistically the
parameters significance from the design of experiments
which is affecting the quality characteristics. From
Table 7, 8 show the results for MRR and TWR, it’s
clearly indicates that T-ON contributes the most
significant in MRR- material removal rate current for
TWR –tool wear rate of micro hole machining which is
affecting the performance. F-Value analysis is used to
determine the process parameters have a significant
effects on the performance characteristic in which F-
value is large .Percentage contribution for both ie MRR
is 39.27% and TWR is 56.219 %
Table 7.ANOVA of MRR
Source DF Adj
SS Adj MS
F -
Value % Contribution
Current 2 2.963 1.4815 1.64 29.704
T-ON 2 3.918 1.9592 2.16 39.278
T-OFF 2 1.283 0.6417 0.71 12.862
Error 2 1.81 0.9052 18.145
Total 8 9.975 100.000
112
Table 8.ANOVA of TWR
Sourc
e
D
F
Adj Adj F -
Valu
e
%
Contributi
on SS MS
Curre
nt 2
0.0001
13
0.0000
57 6.16 56.219
T-ON 2 0.0000
64
0.0000
32 3.51 31.841
T-OFF 2 0.0000
06
0.0000
03 0.34 2.985
Error 2 0.0000
18
0.0000
09 8.955
Total 8 0.0002
01 100.000
Conclusions
From the Experimental analysis of micro hole
machining of ss-316 with dia. 0.7mm (700µm) the
following results are made
For Material removal rate the optimum combination is A3B1C3 (Current 0.8, T.ON 6, T.OFF 8)
For Tool wear rate the optimum combination is A2B1C2 (Current 0.4, T.ON 6, T.OFF 6)
Percentage contribution for MRR is 39.27% where T-ON and for TWR 56.21% Reference
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