The effect of discharge energy and nano Al2O3 on μED milling of Inconel 718

Abstract

Micro EDM is a well-recognized machining process for complex and precise three-dimensional micro features. However, the disadvantages are high machining time, poor surface finish, and a thick recast layer that restricts the wide establishments. Powder mixed EDM (PMEDM) is a recent advancement in the EDM process that enhances the sparking frequency and inter-electrode gap. This paper presents the effect of Al2O3 nanopowder on micro ED milling of Inconel 718 at chosen levels of discharge energy (3.2 μJ to 7.2 μJ, 32 μJ to 72 μJ and 320 μJ to 720 μJ). To understand the dynamics of the process, comprehensive experimental research was carried out using a full factorial design with 60 experiments. Material removal rate, tool wear rate, and surface finish were evaluated. The surface topography and material migration to the machined surface was also studied. The results showed significant improvement of 157%, 20%, and 21% in MRR, TWR, and surface roughness respectively in nanopowder mixed micro-EDM when compared with conventional micro-EDM. The addition of Al2O3 nanopowder reduced crater size in all three discharge energy ranges and reduced carbon deposition on the machined surface.