An experimental investigation of electrical discharge machining (EDM) fast hole drilling of Inconel 718 and Ti6Al4V

Aerospace manufacturing industry demands high level of quality, accuracy, skilled work and precision manufacturing operations. Electrical discharge machining (EDM) which is very prominent amongst the non-conventional machining methods is effectively used in aerospace manufacturing applications. EDM hole drilling is a variation of EDM process and it is preferred to drill holes with high-aspect ratios. This work was undertaken to investigate EDM hole drilling processes and study EDM hole drilling performance on aerospace alloys, namely Inconel 718 and Ti-6Al-4V. Effects of EDM process parameters, such as discharge current, pulse on/off time and capacitance on material removal rates (MRR), electrode wear (EWR) and surface roughness (SR) were analysed throughout the experimental works. The experimental plan was conducted according to the design of experiment (DOE) and the results were statistically evaluated using analysis of variance (ANOVA). Response surface methodology (RSM) was employed in evaluating the drilling performance of the EDM process and mathematical models and optimisation attempts for MRR, EWR and SR were established. The results obtained from the mathematical models and optimisation attempts were verified additional validation experiments.Key Words: EDM, Hole-drilling, Aerospace Alloys