Surface Characterization, Material Removal Mechanism and Material Migration Study of Micro EDM Process on Conductive SiC

Abstract

SiC is an important industrial ceramic and also the fourth hardest ceramic after diamond, boron nitride and boron carbide. Due to very low fracture toughness, it is very difficult to machine SiC using conventional machining methods. EDM can machine such materials irrespective of their hardness. Micro electrical discharge machining (micro-EDM) is an adaptation of conventional EDM process that has similar electro-thermal methods of material removal for manufacturing miniature or micro parts. Micro EDM is used for obtaining burr-free micro dimensional apertures in difficult-to-cut materials. For improved understanding of the micro EDM process and achieve high quality machining on conductive SiC, it is necessary to characterize the machined surface and understand the material removal and material migration mechanism. In this work, micro depth holes were machined in SiC workpiece. The experimentation was planned using Taguchi's L9 theory. A combination of scanning electron microscopy (SEM), white light interferometry (WLI), energy dispersive x-ray spectroscopy (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD) was used to characterize the machined surface and study the material removal and material migration mechanism. It was found that improved characterization and understanding of μEDM can lead to better micro-machining of conductive SiC.