Studies on the influence of nano abrasives mixed dielectric on micro ED milling of Inconel 718 alloy

Abstract

newlineThe present work concentrates on investigating the effect of two nano abrasive powders, namely Silicon Carbide (SiC) and Aluminium Oxide (Al2O3), under different discharge energy regimes on micro-electro discharge milling of Inconel 718 alloy. Inconel 718 is a nickel-based alloy considered as a potential material for metallic Micro Electro Mechanical Systems (MEMS) and micro devices for high-temperature applications based on its superior properties. Mineral oil based dielectric was prepared with different concentrations of nano abrasives SiC and Al2O3. Microchannels were machined on Inconel 718 alloy with the prepared nano abrasive mixed dielectrics under different discharge energies. The material removal rate and tool wear rate were calculated. The surface roughnesses of the micro channels were also measured. The crater morphology and recast layer thickness were analysed. The discharge energy and nano abrasive powder concentration affected the material removal rate and tool wear rate significantly, whereas the type of abrasive seems to be the least significant factor. High material removal rates were achieved under medium discharge energy regimes with 0.4 gram/litre of Al2O3 and SiC nano abrasive mixed dielectrics. The enlargement of the interelectrode gap, reduction in breakdown voltage of dielectric, increased sparking frequency and efficient flushing due to enlarged inter-electrode gap enhanced the material removal rate. The tool wear rate under all energy ranges reduced significantly and an average reduction of 21 % was observed when 0.4 g/l Al2O3 and SiC nano abrasive mixed dielectric was used. The nano abrasive powder interacted with the tool surface and reduced the pyrolysis carbon deposition. The abrasive particles also interacted with photons from the anode and reduced the impact on the tool. This resulted in a reduced tool wear rate.