The critical conditions of brittle–ductile transition and the factors influencing the surface quality of brittle materials in ultra-precision grinding

Based on the indentation experiments under different loads, the critical conditions for the brittle–ductile transition of the brittle materials has been investigated from dynamic grinding, and the factors influencing the surface quality of the brittle materials have been analysed in ultra-precision grinding theoretically. After having carried out the grinding experiments of the brittle materials, it was shown that influence of the average grain size of the diamond wheel on the surface quality is prominent. Compared to the wheel grain size, influence of wheel speed and feed rate on the surface quality is in secondary; these experimental results were consistent with the theoretical analysis. In the case of υs = 1200 m/min, f = 0–20 μm/rev, ap = 0.1–10 μm, only when the average grain size of the diamond wheel is less than 10 μm, can the super-smooth surface (Ra: 6.200 nm, rms: 8.201 nm) be obtained by grinding in the ductile mode.