Influence of SiC addition in Cu-SiC composite electrodes on surface integrity during EDM of ZE41A magnesium alloy using composite desirability optimization

This study investigates the machining performance of ZE41A magnesium alloy with powder-metallurgy-fabricated Cu-SiC composite electrodes containing 5, 10, and 15 wt.% SiC in electrical discharge machining (EDM). The effect of peak current (Ip: 5–15 A), pulse-on time (Ton: 50–150 μs), and SiC content (Sc: 5–15 wt.%) on material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra) was evaluated using RSM. ANOVA revealed that Ip was the most significant parameter, contributing 76.04%, 79.81%, and 65.12% for MRR, TWR, and Ra, respectively. The developed models demonstrated excellent predictive performance, with R2 values for MRR, TWR, and Ra of 99.95%, 99.92%, and 99.94%, respectively. Main-effect analysis showed that MRR increased by 108% when Ip was increased from 5 to 15 A, while TWR and Ra increased by 117% and 70%, respectively. SEM examination showed bigger craters and thicker recast layers, while EDS confirmed the transfer of Cu (2.1 wt.%) and Si (2.5 wt.%) from the Cu-SiC electrode. Multi-response optimization produced an overall composite desirability of 0.9517 at Ip: 14 A, Ton: 75 μs, and Sc: 15 wt.%, yielding predicted MRR, TWR, and Ra values of 22.38 mg/min, 3.88 mg/min, and 4.89 μm, respectively. Confirmation experiments revealed prediction errors less than 5%, validating the proposed optimization strategy for sustainable EDM of ZE41A magnesium alloy.