Experimental investigation and multi-response optimization of wire-EDM performance characteristics

Abstract

Hastelloy is a nickel-based superalloy widely used in demanding marine, nuclear, energy, and aerospace applications because of its high strength and excellent corrosion resistance. Its high hardness and thermal stability, however, make conventional machining difficult. This study investigates the effects of pulse-on time (TON), pulse-off time (TOFF), flushing pressure (FP), and wire feed rate (WF) on material removal rate (MRR) and surface roughness parameters during Wire Electrical Discharge Machining (WEDM) of Hastelloy. An L16 orthogonal array was employed, and the multiple responses were optimized using an integrated Entropy-TOPSIS approach. Entropy was used to determine the objective weights of the responses, while TOPSIS identified the best-performing parameter combination. The optimum condition was obtained at TON = 118 μs, TOFF = 55 μs, FP = 7 bar, and WF = 7 m/min. ANOVA identified TON as the most influential parameter, followed by TOFF, WF, and FP. Residual analysis confirmed the adequacy of the developed model, with normally distributed errors and no significant systematic trends. The findings demonstrate the effectiveness of the Entropy-TOPSIS framework for achieving a balanced combination of machining productivity and surface quality in WEDM of Hastelloy.