Multi-objective optimization of wire-EDM of Inconel 625 by using desirability function approach

Wire electro-discharge machining (Wire-EDM) is one of the most versatile and efficient manufacturing process to machine difficult-to-cut materials. In this experiment, wire-EDM of Inconel 625 work piece material is performed by using zinc coated brass wire as wire electrode and distilled water as dielectric fluid. Input parameters taken during experimentation are pulse-on-time (T_on), pulse-off-time (T_off), and servo voltage (S_v). Here, experiments are conducted as per Taguchi’s experimental design i.e. L₉ orthogonal array to study the effect of machining parameters on the output responses. To access the machining performance of the wire-EDM process during machining of Inconel 625, the output responses considered are material removal rate (MRR), kerf width (K_w), and average surface roughness (R_a) of the machined surface. For multi-objective optimization of these output responses during the wire-EDM process, desirability function approach is used to achieve better machining performance i.e. higher MRR, lower K_w and lower R_a. The optimum parametric setting for better machining performance is obtained to be T_on = 18 µm, T_off = 53 µm, S_v = 23 V. Also, analysis of variance (ANOVA) is performed to study the influence of machining parameters on the overall output performance (composite desirability). Here, pulse-on-time is found to be the highest significant factor with percentage contribution of 64.14% for composite desirability.