An investigation on the effect of alumina nano powder mixed dielectric oil on EDM-assisted precision micro-drilling operation

Abstract

Micro-holes and drilled workpiece dimensions must be more exact in the modern industrial age. Manufacturing micro-scale electronic devices used in automobiles and aerospace components with thermal sinking properties and bio-medical with germicidal properties requires micro-drilling on copper-like materials. Micro-EDM has emerged as a promising technique for micro-drilling. The primary challenge faced in µ-EDM drilling is the effective elimination of debris (mass of workpiece and tool). Therefore, this study aims to investigate the feasible parametric combination (Discharge Energy, Tool Feed Rate, Tool Rotation, and Nano-Powder) to achieve dimensionally correct with better surface characteristic µ-through holes in copper using tungsten carbide micro electrode in micro-EDM. Furthermore, this study examines the effect of Al2O3 nano-powder mixed dielectric on the process performance aspects. ANOVA and PCA-GRA multi-optimization techniques addressed performance aspects (MRR, TWR, and Machining Time) and dimensional aspects (Overcut, Taper Angle, and Aspect Ratio) with visualization of the surface (Texture and Recast Layer). The experimentation found that nano-powder mixed dielectric highly impacted dimensional aspects (Overcut increased by 55.13%, Taper Angle reduced by 37.9%) by diminishing TWR by 12.2% and aspect Ratio by 3.31%. Furthermore, discharge energy affects MRR by increasing 27.9%, and machining time is reduced by 3.48%. The FESEM micrograph illustrated that surface defects (cracks, voids, discharge bubbles, debris accumulations, etc.) were most eliminated, and recast layer thickness was reduced by 34.4% (at 2.81 µj DE) and 56.6% (at 7.81 µj DE) using nano-powder mixed dielectric application.