Large scale molecular dynamics study of nanometric machining of copper

Nanometric machining involves removal of materials at the order of a few nanometers or less. At such a small length scale, molecular dynamics (MD) simulation is an important tool in studying the nanometric machining mechanism and process. In this study, a series of large scale MD simulations with the model size of more than four-million atoms have been performed to study the nanometric machining of copper. The dislocations at finite temperature during the cutting processes are identified and their nucleation and movement are studied. The effects of cutting depth, cutting speed, crystal orientation and cutting direction on the material deformation, lattice defects and cutting forces are investigated. The simulation results show that a smaller cutting depth results in less plastic deformation and fewer dislocations in the workpiece and thus result in a smoother machined surface. It is found that as the cutting depth decreases, the specific cutting force increases rapidly, which shows that the "size effect" exists in nanometric machining. It is observed that a higher cutting speed results in more lattice defects at the cutting region and higher cutting forces. It is revealed that the crystal orientation and cutting direction have a strong effect on material deformation, dislocation movement and cutting forces.