Molecular Dynamics Investigation of Nanometric Cutting of Single-Crystal Silicon Using a Blunt Tool
SNA Kalkhoran and M Vahdati and JW Yan, JOM, 71, 4296-4304 (2019).
A cutting process is strongly affected by depth of cut (h(0)) and tool edge radius (r(e)), the relationship of which is described by relative tool sharpness (RTS=h(0)/r(e)). In nanometric cutting, the depth of cut is far smaller than the tool edge radius, thus the tool is actually a very blunt one with a highly negative effective tool rake angle (~-90 degrees). However, most previous studies have assumed the tool is extremely sharp with a nanometric edge radius, and to date there is very little literature on the cutting mechanism for a blunt tool (RTS<1). In this study, the material deformation/removal behavior and forces under a small RTS from 1 to 0 were investigated via molecular dynamics. The results show that the surface integrity and chip formation are strongly affected by RTS. As RTS is reduced to 0.25 or smaller, rubbing and ploughing occur with no material removal. In such a circumstance, the force angle drops sharply with remarkable subsurface damage formation in the workpiece. These findings are distinctly different from the common belief, and provide new information for the optimization of the silicon wafer manufacturing process.
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