Multi-characteristic optimization of WEDM for Ti-6Al-4V by applying grey relational investigation during profile machining

Abstract

This research work presents multi-quality features optimization while wire electrical discharge machining (WEDM) of Ti-6Al-4V. Taguchi’s L27 orthogonal arrangement is applied to inspect the outcome of governing variables such as pulse-on period, pulse-off interval, discharge voltage, discharge current, wire feed speed and cable tension on the kerf width, material removal rate (MRR), the surface roughness (SR) and overcut during intricate profile manufacturing on Ti-6Al-4V. To optimize all six governing variables, the grey relational investigation (GRI) is applied. The grey relational score is used as a multi-quality unique index (MQUI). From the experimental results the optimal configuration of governing variables obtained is pulse-on period 110 µs, pulse-off interval 55 µs, discharge voltage 40 volts, discharge current 170 Amp., wire feed speed 3 m/min and cable tension 8 gram. ANOVA analysis indicates that pulse-on period is an essential variable concerning the quality outputs. Results of confirmation trials show that the optimal governing variables improved the grey relational score (GRS) from 0.9048 to 0.9226 for the multiple responses. SEM analysis of machined parts shows that at high values of pulse on period and discharge current, deep craters, globules of debris, voids, and micro cracks are formed on the cut surface thus deteriorating the surface finish.