Influence of double-tip scratch and single-tip scratch on nano-scratching process via molecular dynamics simulation

A three-dimensional molecular dynamics model was proposed to study the influences of scratch feed, depth and crystal orientation on the shape and surface quality of the scratched groove during nano-scratching process. In this paper, comparisons were made between the results of double tips simultaneously scratching the surface and those of single tip successively scratching the surface with the same scratch feed, depth and crystal orientation. EAM potential was used to model the interaction of copper atoms, and Morse potential was used to model the interaction between copper and carbon atoms. The residual profiles of scratched grooves and scratching forces were recorded during the simulations. Simulational results show that when single tip scratches the surface at an extremely small feed, the second time scratch significantly influences the previous groove. The second time scratch has a significant influence on the previous groove by increasing scratch depth. Compared with scratching along crystal orientation [1 0 0], scratching along crystal orientation [0 1 1] and [1 1 1] are easy to obtain two parallel grooves. However, when double tips simultaneously scratch the surface regardless of scratch feed, depth and crystal orientation, two parallel grooves are always obtained. Thus, in order to obtain scratched grooves of high quality, it is quite beneficial to design and machine multiple-tip tools.