Effect of tool rake angle on the material removal mechanism transition of single-crystal silicon: a molecular dynamics study

In nanometric cutting, the dominant material removal mechanism can be greatly different with macroscopic cutting process. In this work, molecular dynamics (MD) simulation was carried out to investigate the cutting features of single-crystal silicon. The effect of the tool rake angle and the workpiece crystal orientation on the transition of the material removal mechanism was studied. Theoretical analysis and cutting experiments were conducted to verify the simulation results. The results indicate that with a decrease of the tool rake angle, the material removal mechanism could transform from shear to extrusion and finally no material would be removed. In this process, the position of the stagnation region increases rapidly when the dominant material removal mechanism becomes extrusion and would reache to the uncut surface when no material is removed. The shear to extrusion transition is greatly influenced by the tool rake angle and workpiece crystal orientation while the dominant factor that affect the transition from extrusion to no removal is the position of the stagnation region and frictional force on tool rake face. Furthermore, based on the simulation results and theoretical analysis, when the tool rake angle is decreased, the shear stress plays an important role in the formation of the subsurface damage.