Study of the temperature and stress in nanoscale ductile mode cutting of silicon using molecular dynamics simulation

In nanoscale cutting of brittle materials, it has been found that there is a brittle-ductile transition when the cutting tool edge radius is reduced to nanoscale and the undeformed chip thickness is smaller than the tool edge radius. In order to understand the mechanism of the brittle-ductile transition, the cutting characteristics, such as stress and temperature in the cutting region, have to be investigated. However, since the machining size is very small, on the nanoscales, it's very difficult to measure the temperature and stress in the chip formation zone experimentally. In this study, the molecular dynamics (MD) method is employed to model and simulate the nanoscale ductile mode cutting of monocrystalline silicon wafer. The MD simulation results show that the temperature rise in the cutting zone will affect the diamond tool. In the cutting process, the thrust force is larger than the cutting force. As the tool cutting edge radius increases, the shear stress in the workpiece material around the cutting edge will decrease. When the shear stress is so low that it is insufficient to sustain dislocation emission in the chip formation zone, crack propagation becomes dominating. Consequently, the chip formation mode changes from ductile to brittle. (C) 2007 Elsevier B.V. All rights reserved.