Multi-response optimisation of machining parameters to minimise the overcut and circularity error during micro-EDM of nickel-titanium shape memory alloy

ABSTRACT

Micro-electrical discharge machining (µ-EDM) is one the most favourable process to machine difficult to cut materials in micro-scale with higher accuracy and precision. In this paper, two multi-response optimisation tools called Taguchi’s grey relation analysis (GRA) and response surface methodology (RSM)-based desirability function are used to evaluate optimised micro-machining parameters for minimal overcut and circularity error during µ-EDM of nickel-titanium (NiTi) shape memory alloy (SMA). Taguchi’s GRA revealed that electrode material has the strongest influence on both the responses followed by capacitance and discharge voltage. ANOVA analysis established that electrode material has the highest percentage contribution of 40.15% on both the responses. The optimisation result obtained by Taguchi’s GRA approach is validated by the RSM-desirability function-based technique. The final optimisation result (capacitance 155 pF, electrode material tungsten, discharge voltage 80 V) is a very close agreement with the literature model (capacitance 355 pF, electrode material tungsten, discharge voltage 80 V), with reference to the overcut and circularity error for the improvement of the dimensional accuracy of the micro-holes. Further, the response surface plots disclosed the variation of overcut and circularity error with the process parameters at various levels in a descriptive manner.

KEYWORDS:

• µ-EDM
• NiTi
• SMA
• GRA
• RSM
• optimisation
• desirability function

Acknowledgments

The authors would like to thank Abidi et al. [22] for providing the experimental dataset (Tables 1 and 2) which is adapted with permission from Elsevier, Copyright 2018, License Number 5292320591426 and 5140881068099.

Disclosure statement

No potential conflict of interest was reported by the author(s).