Study on nanometer cutting mechanism of single crystal silicon at different temperatures

Thermal-assisted single point diamond turning technology is currently one of the most important methods for realizing nano-scale machining. However, the nano-chip formation mechanism as the core of the nano-cutting mechanism is still unclear, which limits the development of this advanced technology. In this study, based on the molecular dynamics simulations, the nano cutting behaviour of single crystal silicon at different temperatures were studied. The cutting force, crystal structure, particle motion characteristics, stress-strain distribution and temperature distribution during chip formation process were systematically analyzed. The underlying mechanism of nano-chip formation in single crystal silicon was summarized. The results showed that the chip formation mechanism can be divided into two types: crack and shear. At low temperatures, chips are formed by crack propagation. The concentrated distribution of high stress triaxiality and local high temperatures at the crack tip are the main causes of crack propagation. With an increase in temperature, the chip formation mode gradually changed from crack to shear. The highly resolved shear stress distributed along the slip plane is the main reason for the expansion of the amorphous bands. In addition, it's found that higher quality machined surfaces can be obtained through chip formation process by shear than by crack.