Scratching of copper with rough surfaces conducted by diamond tip simulated using molecular dynamics

The process of material removal of single crystal copper with rough surfaces subjected to nanoscale scratching is studied in the present paper. We explore the key material removal mechanism by means of the observed variation of material removal under different surface roughnesses, tool speeds, scratching directions, tip shapes, feeds, double tip, and single tip. The investigation reveals that a higher peak on the surface reduces the local area roughness, and a higher valley enhances the stability of surface structure. The plastic deformation by means of dislocation loop transfers from the surface of substrate to the interior of workpiece with the rough or smooth surface during scratching process. A higher scratching velocity results in the increasing surface smoothness and reducing the impact on the rough surface atoms. The scratching along the critical angle 45 degrees between scratching direction and surface texture orientation makes the surrounding atoms produce the minimal variation structure, helps to improve the structural stability, and plays an important role in protecting the scratching surface. The double-tip and single-tip scratching under different scratching feeds makes the rough surface perpendicular to the scratching direction substantially covered by chips or side flow. For different tip shapes, a cone diamond tip causes less plastic deformation in the subsurface than a prismatic diamond tip due to using different diamond tips with a contact area unequal.