Characteristics of “dynamic hard particles” in nanoscale ductile mode cutting of monocrystalline silicon with diamond tools in relation to tool groove wear

Abstract

In nanoscale ductile mode cutting of the monocrystalline silicon wafer, micro/nano groove wear on the diamond cutting tool flank face is often observed, which is beyond the understanding based on conventional cutting processes because the silicon workpiece material is monocrystalline with the hardness lower than that of the diamond cutting tool at room temperature. From the investigation of such a phenomenon, a concept of “dynamic hard particles” generated in the chip formation zone as a result of silicon phase transformation from monocrystalline to amorphous was proposed. It was believed that the “dynamic hard particles” caused the groove wear at the tool flank. In this study, the characteristics of such “dynamic hard particles” and their relationship with the diamond tool groove wear have been investigated through molecular dynamics (MD) simulation of nanoscale ductile mode cutting of monocrystalline silicon with diamond tools. The results show that during the cutting process, due to the workpiece material phase transformation from monocrystalline to amorphous, which results in the existence of silicon atom groups with shorter bond lengths in the chip formation zone, “dynamic hard particles” having a dynamic and uneven distribution over the entire chip formation zone are formed. The distribution changes over time and cutting stages. When the cutting runs into a steady state, the “dynamic hard particles” are mostly distributed in the lower portion of chip formation zone, contributing directly to three body abrasions on the tool flank face, causing groove wear at tool flank. The dynamic distribution of the “dynamic hard particles” also causes the uncertainty of the groove wear locations at the tool flank.