• Corresponing author U Ashok Kumar,E-mail address: uak.oumech@gmail.com • 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

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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

1. Uhlmann E., Piltz S., Doll U., Machining of micro/miniature dies and moulds by electrical dischage machining – recent development, Journal of Materials Processing Technology 167; 2005, p. 488-493

2. S.H. Huang, F.Y. Huang and B.H. Yan, “Fracture strength analysis ofmicro WC -shaft manufactured by micro-electro-discharge machining,” Int. J. of Adv. Manuf. Technol., Vol.26, 2005, pp. 68-77.

3. M. P. Jahan, Y. S. Wong and M. Rahman, “A study on the quality micro-hole machining of tungsten carbide micro-EDM process using transistor and RC-type pulse generator,”

Int. Mater. Proc. Tech., vol. 209, 2009, pp. 1706 -1716.

4. M. Manohar, T. Selvaraj, D. Sivakumar, Shibu

Gopinath, Koshy M. George “Experimental Study to Assess the Effect of Electrode Bottom Profiles while Machining Inconel 718 through EDM Process”Original Research ArticlePages 92-104 Procedia Mateials Science Volume 6, Pages 1-2000 (2014)3rd International Conference on Materials Processing and Characterisation (ICMPC 2014

5. Swapan Barman, Vijay, Nagahanumaiah, Asit Baran Puri “Surface Texture and Elemental Characterization of High Aspect Ratio Blind Micro Holes on Different Materials in Micro EDM” Procedia Materials Science 6 ( 2014 ) 304 – 309 Volume 6, Pages 1-2000 (2014)3rd International Conference on Materials Processing and Characterisation (ICMPC 2014)

6. T. Chinnadurai, S. Arungalai Vendan

“Contemplating the Performance Measures of Wire Cut EDM Based on Process Parameters for AISI 4140” Materials Today: ProceedingsVolume 2, Issues 4–5, 2015, Pages 1067–1073,4th International Conference on Materials Processing and Characterzation

7. D. Amrish Raj, T. Senthilvelan “Empirical Modelling and Optimization of Process Parameters of machining Titanium alloy by Wire-EDM using RSM” Materials Today: ProceedingsVolume 2, Issues 4–5, 2015, Pages 1067–1073,4th International Conference on Materials Processing and Characterzation

8. Amoljit Singh Gill, Sanjeev Kumar “Surface

Alloying by Powder Metallurgy Tool Electrode Using EDM Process”Materials Today: ProceedingsVolume 2, Issues 4–5, 2015, Pages 1723–1730,4th International Conference on Materials Processing and Characterzation

9. U Ashok Kumar, P. Laxminarayana “Study of surface morphology on micro machined surfaces of AISI 316 by Die Sinker EDM” Materials today: proceedings 4(2):1285-1292. December 2017, DOI: 10.1016/j.matpr.2017.01.149

113

10. U Ashok Kumar, P. Laxminarayana, "Study of

Tool Wear Optimization in Micro Holes Machining of SS316 by Die Sinker Electrical Discharge Machining", International Journal of Scientific Research in Multidisciplinary Studies, Vol.3, Issue.7, pp.1-4, 2017

11. U Ashok Kumar, P. Laxminarayana “Optimization of process parameters of Material Removal Rate in Micro hole Machining by Die sinker EDM, IOSR Journal of Engineering (p): 2278-8719 Vol. 07, Issue 07 (July. 2017), ||V1|| PP 61-65

12. Pratyusha J, Ashok kumar.U, Laxminarayana .P “ Optimization of Process Parameters for Milling Using Taguchi Methods “International Journal of Advanced Trends in Computer Science and Engineering, Vol.2 , No.6, Pages : 129-135 (2013)

13. U Ashok Kumar, P. Laxminarayana “Optimization of Electrode Tool Wear in micro holes machining by Die Sinker EDM using Taguchi Approach” Materials today: proceedings 5(1):1824-1831, January 2018, DOI: 10.1016/j.matpr.2017.11.281