Investigating the effects of different electrodes on Al6061-SiC-7.5 wt% during electric discharge machining

This research aimed to investigate the effects of different electrodes on the performance of electric discharge machined Al6061-SiC-7.5 wt% composite fabricated by squeeze casting process. The effects of three most significant input parameters including current intensity, pulse duration, and duty cycle on material removal rate (MRR), surface roughness (Ra), and electrode wear ratio (EWR) were investigated using copper, brass, and stainless steel electrodes. To improve the machining performance, graphene nanoparticles (4 wt%) were contaminated in dielectric fluid. Response surface methodology (RSM) based on central composite design was employed for design of experiments and development of mathematical models. Adequacy and validity of developed mathematical models were verified by ANOVA and confirmatory tests respectively. For multi-response optimization, desirability function approach was used to identify the optimum input parameters. For all electrodes, current intensity was observed as the most significant input parameter influencing MRR, Ra, and EWR followed by pulse duration and duty cycle. Comparative analysis revealed brass electrode as better option for MRR and Ra. Stainless steel, on the other hand, was identified as a better alternative for EWR. While taking copper as reference, 23.2% higher MRR and 20.3% better surface finish were achieved through brass electrode as compared to stainless steel electrode which provided 35.3% and 32.3% less MRR and surface finish respectively. EWR for stainless steel and brass electrode decreased by 25% and increased by 45.5% respectively with reference to copper. Multi-response optimization yielded compound desirability of 81%, 78.8%, and 77.1% for copper, brass, and stainless steel electrodes respectively for the machining of Al6061-SiC-7.5 wt% composite.