In nanometric cutting, the dominant material removal mechanism can be greatly different with macroscopic cutting process. In this work, molecular dynamics (MD) simulation was carried out to investigate the cutting features of single-crystal silicon. The effect of the tool rake angle and the workpiece crystal orientation on the transition of the material removal mechanism was studied. Theoretical analysis and cutting experiments were conducted to verify the simulation results. The results indicate that with a decrease of the tool rake angle, the material removal mechanism could transform from shear to extrusion and finally no material would be removed. In this process, the position of the stagnation region increases rapidly when the dominant material removal mechanism becomes extrusion and would reache to the uncut surface when no material is removed. The shear to extrusion transition is greatly influenced by the tool rake angle and workpiece crystal orientation while the dominant factor that affect the transition from extrusion to no removal is the position of the stagnation region and frictional force on tool rake face. Furthermore, based on the simulation results and theoretical analysis, when the tool rake angle is decreased, the shear stress plays an important role in the formation of the subsurface damage.

在纳米切削中，主要的材料去除机制与宏观切削过程有很大不同。在这项工作中，进行了分子动力学（MD）模拟以研究单晶硅的切割特征。研究了刀具前角和工件晶体取向对材料去除机制转变的影响。通过理论分析和切削实验验证了仿真结果。结果表明，随着刀具前角的减小，材料去除机制可以从剪切转变为挤压，最终没有材料被去除。在这个过程中，当主要的材料去除机制变为挤压时，停滞区域的位置迅速增加，并且在没有材料去除时将到达未切割表面。从剪切到挤压的转变受刀具前角和工件晶体取向的影响很大，而影响从挤压到无去除转变的主要因素是停滞区的位置和刀具前刀面上的摩擦力。此外，基于模拟结果和理论分析，当刀具前角减小时，剪切应力在次表面损伤的形成中起重要作用。从剪切到挤压的转变受刀具前角和工件晶体取向的影响很大，而影响从挤压到无去除转变的主要因素是停滞区的位置和刀具前刀面上的摩擦力。此外，基于模拟结果和理论分析，当刀具前角减小时，剪切应力在次表面损伤的形成中起重要作用。从剪切到挤压的转变受刀具前角和工件晶体取向的影响很大，而影响从挤压到无去除转变的主要因素是停滞区的位置和刀具前刀面上的摩擦力。此外，基于模拟结果和理论分析，当刀具前角减小时，剪切应力在次表面损伤的形成中起重要作用。