Single-grit modeling and simulation of crack initiation and propagation in SiC grinding using maximum undeformed chip thickness

The application of engineering ceramics is often limited due to its low machining efficiency and surface/subsurface damage, of which surface/subsurface micro-crack is one of the major challenges during grinding. Single-grit simulation has been utilized to investigate the initiation and propagation of individual cracks in SiC grinding under controllable maximum undeformed chip thickness (M-UCT). The simulation results indicate that the material removal is dominated by the ductile-regime grinding when M-UCT is kept below 0.29 μm, resulting in the workpiece surface morphologies are less dependent on the wheel speed. Brittle removal mode becomes more significant and transverse cracks are initiated once M-UCT exceeds 0.3 μm. In brittle-regime, wheel speed is found to be a crucial factor of workpiece surface integrity, and median cracks can be effectively inhibited by moderate wheel speed. High speed grinding experiment in conjunction with a high workpiece speed is proposed as a solution for the brittle-to-ductile transition, resulting in desired surface morphologies and residual stress distribution. The M-UCT serves as a basis for users to select optimal process parameters.