Enhancing EDM performance of Monel-400 super alloy through process parameter optimization: RSM-based experimental and microstructural analysis

A nickel-copper alloy Monel-400 renowned for its corrosion resistance and thermal properties finds extensive application in chemical, fitting, fastener, and marine industries. However, machining intricate, delicate components from this alloy using conventional methods presents significant challenges. EDM is a non-traditional process capable of producing precise, high-quality surfaces, which emerges as a viable alternative. The die-sinking EDM of Monel-400 are investigated with a particular focus on the machined surface microstructure. A Box-Behnken design was employed to evaluate the influence of discharge current, pulse-on time, and voltage gap on material removal rate, tool wear rate, and surface roughness. Results indicate that impact of peak current and pulse-on time are primary determinants of Monel-400 machining characteristics. While impact of peak current exhibited the most significant impact on MRR, pulse-on time was identified as the critical factor affecting tool wear rate and surface roughness. A comprehensive metallographic examination of the machined surface was conducted to elucidate wear mechanisms.