Effect Of Diamond Tool Swing On Surface Anisotropy In Ultra Precision Cutting Of Single-crystal Silicon

Single-crystal silicon is widely used in optics,integrated circuits,solar cells and micro-electromechanical systems,but its hardness,brittleness and surface anisotropy restrict further improvement in performance.In order to improve the cutting surface quality of single-crystal silicon,molecular dynamics simulation method was used in this paper to carry out cutting simulation on typical single-crystal silicon surface（100）（110）（111）and the method of reducing anisotropy was discussed.First of all,a molecular dynamics simulation model was established,and the tool parameters and workpiece parameters in the molecular dynamics model were determined.The potential function,boundary conditions,ensemble and time step suitable for this model were selected.Secondly,the swing angle of diamond was set as 15°,20°,25°,30°,35° and 40° for simulation.By analyzing the depth of subsurface damage,the removal of atoms,the formation of the amorphous layer,the cutting force and the friction coefficient on the three typical crystal surfaces of single-crystal silicon during the cutting process,the tool swing angle which is beneficial to reduce the anisotropy of the cutting surface was obtained.Thirdly,a tool swing simulation model with cutting depth of 3 nm,5 nm and 7 nm was established to analyze the effect of tool swing angle on the morphology of the cutting surface,the coordination number of phase transformation and hydrostatic stress at different cutting depths.A tool swing angle of 25° was considered to be beneficial to slow down the reduction of cutting surface quality caused by the increase of cutting depth.Finally,a simulation model with a cutting depth of 3 nm,tool edge radius of 4 nm,6 nm,8 nm and a cutting depth of 7 nm,cutting edge radius of 8 nm,10 nm,12 nm were established.The subsurface damage,chip removal rate,cutting force and friction coefficient were analysed.Under the condition of cutting depth of 3 nm,the effect of tool swing with cutting edge radius of 4 nm,6 nm and 8 nm on the surface quality of single-crystal silicon has been studied.The tool swing with different radius of cutting edge had no significant effect on reducing the anisotropy of cutting surface.