Multi-objective Optimization of Electrical Discharge Machining Process During Machining of NiTi Alloy Using Taguchi and Utility Concept

Abstract

Shape memory alloy namely NiTi alloy is one such advance material which imposes machinability issues when cut by conventional processes. Non-traditional machining process namely electrical discharge machining process overcomes the problem faced by conventional process. However, electrical discharge machining process has low material removal rate and high tool wear rate. Hence, the present study focuses on multi-objective optimization of electrical discharge machining process parameter for maximization of material removal rate and minimization of tool wear rate using Taguchi method and Utility concept. In present investigation NiTi alloy has been used as workpiece material and electrolytic copper as tool electrode. Experiments have been designed based on Taguchi’s L₃₆ (2² × 3³) mixed orthogonal array have been carried out on-die sink type of electric discharge machine. In the present study process parameter such as gap current, pulse on time, pulse off time have been considered at three levels and workpiece electrical conductivity and tool electrode electrical conductivity have been considered at two levels. Based on Taguchi analysis workpiece electrical conductivity, tool electrode electrical conductivity, gap current and pulse on time are found significant process parameters that affect the material removal rate and tool wear rate. From this work optimal values of process parameters that provides optimum material removal rate of 6.31 mm³/min and tool wear rate of 0.031 mm³/min are second level of work electrical conductivity (A2): 4219 S/m, second level of tool electrical conductivity (B2): 26316 S/m, third level of gap current (C3): 16 A and second level of pulse on time (D2): 38 μs.