Experimental Investigation of Microcutting Mechanisms in Oxide Ceramic CM332 Grinding

The paper contains an experimental study of microcutting intended to help the optimization of the grinding process of the oxide ceramic CM332 (99.5% Al₂O₃) grinding. The need for investigating the mechanisms occurring between the abrasive material and the ceramic is imposed by the fact that grinding is the dominant technology used to achieve the required quality of the workpiece surface finish. The microcutting process was performed with a single diamond cone-shaped grain of tip radius of 0.2 mm at varying depths of cut. The investigations were carried out to determine the normal and tangential cutting forces, the critical penetration depth and the specific grinding energy as a function of the grain penetration speed and depth. The critical grain penetration depth separating ductile flow from brittle fracture falls within the 4–6 μm range. The values of the critical penetration depth are also consistent with the results of changes in the cutting forces and the specific grinding energy. The chip formation mechanism is associated with the presence of median/radial and lateral cracks, ductile flow, chipping along the groove, and crushing beneath the diamond grain, all this affecting the quality of the ceramic's machined surface.