Sintered diamond as a hybrid EDM and grinding tool for the micromachining of single-crystal SiC

Sintered diamond was used as a hybrid tool for micro-scale electrical discharge machining (EDM) and grinding of single-crystal SiC to achieve both high efficiency and surface integrity. Material removal behavior, surface topography, and subsurface damage for both process steps were investigated under various conditions. The results showed that SiC decomposed into Si and C during EDM, creating a very thick recast layer which had remarkably lower hardness than the bulk. Owing to the electrical dressing effect in EDM, diamond grains protrude out of tool surface and grind the recast layer in a ductile manner with low tool wear. An extremely smooth surface (Ra = 1.85 nm) was obtained.