Process optimization in micro electrical discharge machining of carbon kevlar hybrid composite using TOPSIS

This work is an experimental investigation and multi-response optimization of micro-electrical discharge machining (µEDM) of carbon-Kevlar hybrid composite (CKHC). Based on the chosen input factors namely voltage (V), EDM feed (EF) and tool speed (TS), the experimental runs were fixed as per Taguchi's L9 orthogonal array. Single and multi-response optimization were carried out using Taguchi and technique for order of preference by similarity to ideal solution (TOPSIS). The responses selected for the study were machining time (MT) and degree of circularity (DOC). The Taguchi analysis identified the optimal input parameter values for minimal MT as a V of 180 volts, EF of 2 μm/sec, and TS of 1000 rpm. The corresponding values for the maximum DOC were 120 volts, 2 μm/sec, and 1000 rpm. Analysis of variance (ANOVA) revealed that voltage significantly affects the variation in MT. However, the DOC is mostly affected by the change in TS. The optimal values of V, EF, and TS obtained from TOPSIS were 150 volts, 4 μm/sec, and 1000 rpm. An improvement of 0.757881 in the preferred solution for optimal settings was confirmed from the analysis. Images from scanning electron microscopy (SEM) confirmed the overcut of the machined micro-holes.