Analysis and Optimization of Recast Layer Thickness, Radial Overcut, and Material Removal Rate in Electrical Discharge Machining of Magnesium Alloy-ZE41 with Different Electrodes

ZE41 magnesium alloy is widely used in aerospace, automobile, and biomedical industries due to light weight and high strength to weight ratio compared to aluminum and steel. In the present study, EDM machining of ZE41 is carried out considering input parameters as three electrode materials, i.e., copper, brass and EN8, peak current, pulse-on time, and pulse-off time on recast layer thickness, radial overcut, and metal removal rate. Experiments were conducted based on Taguchi’s L27 orthogonal array, and results were analyzed using analysis of variance. Multi-objective optimization was performed using analytical hierarchy process coupled with TOPSIS. Analysis of results revealed that electrode material, peak current, and interaction of electrode material and peak current had significant effects on both recast layer thickness and metal removal rate. Electrode material and peak current had significant effects on radial overcut. Pulse-on time and pulse-off time were insignificant in all objectives. Optimization results indicated that the best solution obtained by proposed method corresponds to brass electrode, peak current of 18 Amps, pulse-on time of 100 μs, and pulse-off time of 100 μs. Finally, SEM analysis showed that machined surface at optimal levels obtained by TM-AHP-TOPSIS method provided better surface integrity.