Recent Advances in Machining of Composite Materials by Electrical Discharge Machine

Abstract

Composites are being used since decades and imparting excellent properties comparatively. It may be used in numerous industries because of its light weight and specific strength. Machinability of these materials is a concerned aspect. Conventional and The composites have been machined using unconventional machining techniques. Conventional methods are less suitable than non-conventional quoting the best surface finish and ability to machine complex parts. This article investigates the suitability of thermo-electric process for the machining of composites for higher surface quality and material removal. It includes the study of machining by die sinking, wire cut, powder mixed electric discharge machine in different matrix based composites along with the variation of reinforcement. Electric Discharge Machining (EDM) finds its suitability in machining of different metal matrix composites (MMC) more than the Polymer Matrix Composite (PMC) and Ceramic Matrix Composites (CMC). Variation in input parameters listed as Pulse duration, Voltage, Peak Current and Polarity is studied to obtain the optimum resulting parameters as Material Removal Rate (MRR), Surface Roughness (SR), Electrode Wear Rate (EWR) and Kerf Width. Material removal in PMC is 16% more in parallel fibre direction than with perpendicular. Low electrical conductance and high hardness of CMCs limits the use of EDM while natural ceramics are found more suitable for machining. Gap voltage, pulse on time and current are found most crucial in machining MMCs while quantifying material removal and surface roughness.