Challenge to EDM Slicing of Single Crystal SiC with Blade Electrode Utilizing a Reciprocating Worktable

Single crystal silicon carbide is a promising material for producing next-generation power electronic devices owing to its outstanding physical properties of wide band gap, high dielectric strength, high heat resistance and high electron saturation drift velocity etc. However, slicing of SiC wafer is very time and cost consuming with conventional abrasive multi-wire saw method due to the extremely high hardness of SiC, especially when the diameter of SiC ingot becomes larger. In recent years wire EDM slicing method is being developed as an alternative method for wafering SiC ingots. However, wire vibration and wire breakage problems are inevitable in the process. Wire vibration causes a low cutting accuracy and wire breakage results in a low cutting efficiency. In this study, aiming to solve these problems and improve the EDM slicing performances of SiC, a new EDM wafering method which utilizes a blade electrode is proposed. The slicing process was realized by applying a relative motion between a tensioned blade tool electrode and a workpiece making use of a reciprocating worktable. The development of the experimental setup and the machining experiments are described in detail in this paper. The tool wear ratio, slicing speed, and kerf loss were investigated through slicing experiments and the characteristics of this new method are discussed.