Wednesday, January 8, 2014

Study of EDM cutting of single crystal silicon carbide

Electrical discharge machining (EDM) is developing as a new alternative method for slicing single crystal silicon carbide (SiC) ingots into thin wafers. Aiming to improve the performance of EDM slicing of SiC wafers, the fundamental characteristics of EDM of SiC single crystal were experimentally investigated in this paper and compared to those of steel. Furthermore, EDM cutting of SiC ingot by utilizing copper foil electrodes was proposed and its performance was investigated. It is found that the EDM characteristics of SiC are very different from those of steel. The EDM machining rate of SiC is higher and the tool wear ratio is lower compared to those of steel, despite SiC having a higher thermal conductivity and melting point. Thermal cracks caused by the thermal shock of electrical discharges and the Joule heating effect due to the higher electrical resistivity are considered to be the main reasons for the higher material removal rate of SiC. It is concluded that the new EDM cutting method utilizing a foil electrode instead of a wire electrode has potential for slicing SiC wafers in the future.
Highlights
• Big difference was found between wire EDM characteristics of SiC and cold tool steel SKD11.
• Fracture generation may contribute to the material removal process of EDM of SiC.
• A new EDM cutting method utilizing foil electrode was proposed and investigated.
• Short pulse duration was more suitable for EDM SiC.
• Minimum kerf width of around 100 μm was obtained utilizing the foil EDM method.

Source:Precision Engineering

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