Employment of cylindrical electrolytic copper grade electrode under EDMed Inconel 825 super alloy: emphasis on machining behavior accompanied with surface topography for sustainability

The present study embraces two-fold sustainability benefits where in first-fold, minimum power consumption (Pc) and machining time (Mt) escort one pillar of sustainability named as environmental sustainability. Moreover, the highest material removal rate (MRR) reduces manufacturing costs and embraces the second pillar of sustainability named as economic sustainability. The study is experimentally conducted on globally emerging Inconel 825 super alloy with a copper electrode in EDM. The sustainable machining is evaluated under a cluster of 8 input process parameters, i.e., spark gap (Sg), gap voltage (Vg), pulse on time (Ton), pulse off time (Toff), peak current (Ip), servo feed (Sf), depth of cut (Dc), and difficulty index (Di) under multi objective optimization (MOO) domain. The study has originally devised two novel approaches based on Taguchi, i.e., simple additive weighting (SAWTAG) and grey relational analysis (GRATAG). Toff is found as the chief significant parameter having p values of 0.005 and 0.002 respectively. Dc is found as the second significant parameter with p values of 0.061 and 0.071 respectively. Significant improvements of 0.16262 and 0.48371 are recognized in conformity experiment under GRATAG and SAWTAG approaches; optimal parametric setting is found as Sg 2 Vg 3 Ton 1 Toff 1 Ip 3 Sf 1 Dc 1 Di 1 , which is experimentally validated as robust decision. Furthermore, the proportional contribution of process parameters is estimated where GRATAG reflected 41.11% and SAWTAG reflected 47.29% of the contribution of pulse off time respectively. The study investigated surface topography for highlighting the effects of process parameters on heat-affected layers, machining debris, and surface cracks. It is examined with an increase in Ip and Vg; MRR increases and machining time decreases. Moreover, it is also noticed that an increase in Vg prevents irregularities such as micro voids and re-solidified droplets in machining.