Modeling and optimization of Wire-EDM parameters for machining of Ni_55.8Ti shape memory alloy using hybrid approach of Taguchi and NSGA-II

In the present research, Ni_55.8Ti shape memory alloy has been machined by wire electric discharge machining (wire-EDM) process. The effects of input parameters such as spark gap voltage, pulse on-time, pulse off-time, and wire feed on productivity, i.e., metal removal rate (MRR) and surface quality, i.e., mean roughness depth (R_z), have been investigated. Empirical modeling and ANOVA study have been done after conducting 16 experiments based on Taguchi’s L₁₆ design of experiment technique. Ranking and crowding distance–based non-dominated sorting algorithm-II (NSGA-II) is used for process optimization. The error percentage varies within ± 6% between experimental results and the predicted results developed by NSGA-II. It has been observed that the wire-EDM machining of Ni_55.8Ti alloy at optimum parameters resulted in improved MRR —0.021 g/min—and surface quality with good surface finish (R_z—6.2 μm) and integrity as significant reduction in the formation of cracks, lumps, and deposited layers.