Molecular dynamics analysis of the effect of surface flaws of diamond tools on tool wear in nanometric cutting

Despite the advances in the fabrication technologies of diamond cutting tools, surface flaws or imperfections are unavoidable to some degree. This paper investigates the effect of the surface flaws of the diamond tool surfaces on the tool wear in nanometric cutting using molecular dynamics (MD) simulation. The results of a statistical study of the detachment of atoms show that the material loss from the flawed region is one order of magnitude larger than that from the flawless region. The average principal cutting force is also found to decrease while that for the average thrust force increases with increasing depth of the flaw. These responses are in agreement with the typical force signals in cutting experiments. With the presence of a surface flaw, there is a lower fluctuation of the cyclic force that is possibly associated with the hindering of the formation of shear bands in the workpiece. An analysis of the crystal structures revealed that a cluster or a chain of carbon atoms was pulled and peeled off from these weak covalent networks of the exposed high-indexed facets in the MD simulations. These phenomena accelerate the tool wear and explain the effect of the flaws on the microscopic wear resistance of diamond tools.