Molecular dynamics simulation to investigate the orientation effects on nanoscale cutting of single crystal copper

Abstract

The present study investigates the effect of six different crystal orientations on the nanoscale cutting operation carried out on single crystal copper (Cu) at various ratios of uncut chip thickness (a) to cutting edge radius (r). The study is focused on various aspects of cutting operation which include the material deformation mechanism, subsurface deformation, cutting forces, specific cutting energy, ploughing effect and surface roughness. Molecular dynamics simulation (MDS) was performed for the six orientations at five different a/r ratios varying from 0.1 to 2. The MDS results reveal that the material removal and shear deformation mechanisms are distinct for different crystal orientations. 〈1 1 0〉 is the slip direction along which the dislocations propagate predominantly. Maximum material removal occurs for the (0 0 1)[ 0] orientation which is 45% higher than its minimum counterpart in the (1 1 1)[1 0] crystal orientation at a/r equals to 2. Results of cutting forces as well as specific cutting energy plots show that the crystal orientation {1 1 0}〈0 0 1〉 is difficult to cut whereas crystal orientation {1 1 1}〈1 1 0〉 is easier to cut in nanoscale cutting of Cu. Based on the surface roughness calculation, it is observed that surface quality is highest for the crystal orientation while cutting on (0 0 1)[ 0] and lowest for the crystal orientation ()[1 0 0]. Nanocutting of Cu with larger dimensions used to reduce the size effect shows that there is an increase of ∼275% in the dislocation density for the maximum dislocated crystal orientation (0 0 1)[ 0] when the tool edge sharpness is increased from 2 nm to 5 nm.