A study of chip formation in ductile-regime machining of 6H silicon carbide by molecular dynamics

Much effort have been devoted to the ductile regime machining of silicon carbide (SiC) in recent years. However, a thorough understanding on the mechanism of chip formation has not been achieved. In this study, large scale molecular dynamics simulations are performed to investigate the ductile-regime machining of 6H SiC. It is found that the mechanism of chip formation transforms from shearing to extrusion when the tool rake angle varies from 0° to -40°. The nature of plastic deformation is slipping processes on the basal slip system of 6H SiC and shearing along several inclined planes. Under a rake angle of -40°, a 'pseudo edge' is observed in front of the cutting edge throughout the cutting process. Under a rake angle of -20°, a periodic process of formation and vanishing of 'pseudo edge' is observed. The formation of 'pseudo edge' leads to a decrease in the principle cutting force, and its vanishing is followed by increase of principle cutting force.