Optimisation of WEDM parameters on Nitinol alloy using RSM and desirability approach

ABSTRACT

Machining of Nitinol alloy is complicated by the traditional process due to severe strain hardening and low thermal conductivity, which prompts high tool wear and indigent surface quality. Wire Electro Discharge Machining (WEDM) has been most commonly used for machining Nitinol alloy. In this paper, the effect of input attributes such as pulse on time (T_on), pulse off time (T_off), peak current (I_peak) and voltage (V) on metal removal rate (MRR) and surface roughness (SR) during WEDM of Nitinol alloy have been investigated. Experiments were conducted according to central composite design (CCD) of response surface methodology (RSM). Analysis of variance (ANOVA) was used for studying the effect of input attributes and their interactions. It is perceived that at smaller values, T_on and I_peak are more significant attributes for improving the MRR and surface finish. The optimum conditions are obtained for minimising surface roughness and maximising MRR using RSM and Desirability analysis. Confirmation test was conducted with optimum input attributes where the estimated values of the output attributes were contrasted with the experimental results. It was established that the experimental and the estimated values are in very close agreement.

KEYWORDS:

• Nitinol
• WEDM
• response surface methodology
• central composite design
• metal removal rate
• surface roughness
• desirability
• optimisation

Acknowledgments

The authors would like to appreciate Kellogg’s research labs United States of America for supplying Nitinol alloy in rod form. They are also thankful to Defence Research and Development Laboratory, Hyderabad India, for providing the necessary machine facilities of WEDM and for assistance during experiment. The authors thank Dr P. Padaikathan Senior Scientific Officer, Department of Material science Engineering, Indian Institute of Science Bangalore, India for getting DSC curve for the research work. The author(s) received no financial support for the research, authorship, and/or publication of this article.

Disclosure statement

The author(s) declares that there is no potential conflict of interest with respect to research, authorship, and/or publication of this article.

Additional information

Notes on contributors

Naresh Chakala

Naresh Chakala is currently pursuing his PhD in the Mechanical Engineering Department at National Institute of Technology, Warangal, India. His interested subjects are unconventional machining, Smart materials, optimisation, Super alloys, Design of Experiments, Materials Characterisation, etc. He completed his M.Tech. in the year 2009. He completed his B.Tech. in the Mechanical Engineering Department at Sri Venkateswara University, Tirupati, India, in the year 2007.

P. Subhash Chandrabose

P. Subhash Chandrabose. is currently working as Associate Professor in the Department of Mechanical Engineering, National Institute of Technology, and Warangal, India. His research interests are Machining of Super alloys, Composite materials, unconventional machining Laser assisted machining, Reliability, Optimisation, Design of experiments, etc. He completed his PhD at National Institute of Technology, in the year 2013. He has published 12 papers in reputed international journals, presented his research work at 13 international conferences and four national conferences. Under his supervision one candidate was awarded PhD; he also supervised 15 M.Tech. projects and 8 B.Tech. projects. Currently, he is supervising 5 PhD’s, 4 M.Tech. students and 1 B.Tech. Project.

C.S.P Rao

C.S.P Rao is currently working as Director of National institute of Technology Andhra Pradesh. Did his post-graduation in production Engineering and PhD from National Institute of Technology Warangal (Formerly REC Warangal). Prof. C.S.P Rao had about 30 years of Teaching and Research experience. His research interests are Automation, CIM, Soft Computing, PLM, Simulation, CNC, Optimisation, Machining, Composite Materials, Super alloys, etc. He authored three text books CAD/CAM, Production Technology and Auto CAD. Two more books namely Robotics and Soft Computing Techniques are in press. Prof C.S.P Rao had excellent research experience. He guided 30 PhD scholars and guiding 9 PhD works. He published more than 250 Technical papers in international Journals and conferences etc., He guided about 150 M. Tech students projects and executed R&D projects worth 4.25 crore. He received ‘Engineer of the year award’ and ‘Scientist of the year awards’ in the year 2008 from combined state of Andhra Pradesh.