Modeling and optimization of Wire-EDM parameters for machining of Ni55.8Ti shape memory alloy using hybrid approach of Taguchi and NSGA-II

In the present research, Ni55.8Ti 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 (Rz), 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 Ni55.8Ti alloy at optimum parameters resulted in improved MRR —0.021 g/min—and surface quality with good surface finish (Rz—6.2 μm) and integrity as significant reduction in the formation of cracks, lumps, and deposited layers.