Effect of Process Parameters in Electric Discharge Machining of AZ31 Magnesium Alloy

In modern-day scenario, AZ31 magnesium alloy is considered as a suitable alternative to iron and aluminum in a wide variety of medical, aerospace and automobile applications due to high strength-to-weight ratio and other excellent physical properties. In all the applications, the geometrical accuracy of the products plays a vital role. Electrical discharge machining (EDM) has emerged as a prominent manufacturing process to achieve geometrical accuracy as per the requirements and standards. A hole of diameter 10 mm in a flat plate made of AZ31 alloy is identified as the part feature for investigation in this study. The aim of this work is to optimize and investigate the effect of both qualitative and quantitative process parameters such as discharge current (I), pulse-on time (T_ON), pulse-off time (T_OFF), electrode material (M) on critical-to-quality geometric features such as overcut (OC), tapercut (TC), circularity (CIR) and cylindricity (CYL). The experiments are carried out based on Taguchi’s L16 orthogonal array. Pulse-on time and discharge current are found to have a significant effect on the geometrical accuracy when compared with other process parameters. Regression models are developed for prediction of response parameters, and the results predicted by the models are found to correlate significantly with the results from experiments.