It has already been confirmed that wire electro-chemical discharge machining (WECDM) is effective for cutting ceramic materials in two-dimensional and complicated contours. However, the machining mechanism is still unknown. To elucidate the mechanism, three kinds of machined surfaces, namely, surfaces machined by WECDM, CO₂ laser machining, and laser-assisted chemical etching with a CO₂ laser and KOH solution were investigated using EPMA (Electron-Probe X-ray Micro Analyzer) and SEM (Scanning Electron Microscopy). Furthermore, chemical analyses of the electrolyte including the debris produced by WECDM were carried out. The results show that the material removal in WECDM proceeds not by the melting of materials but the etching of grain boundaries by high-temperature electrolyte during discharge.

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