Micro electro discharge milling of titanium super alloy: Analysis of material removal rate and surface roughness

This paper presents the machinability of titanium super alloy Ti-6Al-4V using micro electro discharge milling (Micro-ED Milling). Material removal rate (MRR), tool wear rate (TWR) and surface roughness were analysed using L18 orthogonal arrays of experiment. Based on analysis of variance (ANOVA) and signal-to-noise (S/N) ratio, empirical models have been developed. Optimum values of micro-ED milling parameters to achieve maximum MRR, minimum TWR and minimum surface roughness (R_a and R_y) were obtained. The optimum parameters were found to be 100 nF capacitance and 80 V gap voltage which leveraged 57.8 µg/s MRR and 0.96 μg/s TWR with 90% desirability. In addition, the optimum parameters for the minimum surface roughness were found to be 1 nF capacitance and 80 V gap voltage which produced 0.086 µm R_a and 0.63 μm R_y with 99% desirability. Experimental studies were conducted using optimum micro-ED milling parameters to validate the results. It was found that the predicted values were within 10% of the experimental values.