Investigating elastic recovery of monocrystalline silicon during plunging experiments with chamfered diamond tools

Abstract

This study investigates the relationship between elastic recovery and friction during ductile mode machining of monocrystalline silicon. Plunging experiments were performed on an ultra-precision CNC machining center as the silicon work material was rotated. This approach allowed for investigating the combined effect of varying crystal directions and increasing depth on elastic recovery, pressures, and friction. A diamond cutting tool with a chamfered edge that maintains a constant negative rake along the cutting edge was used in plunging tests. Considering the importance of flank face contact area on friction and pressure distributions at the cutting zone, a non-linear expression is proposed to model the elastic recovery ratio as a function of groove depth. It is then employed in an analytical machining model to calculate the variation of pressure and coefficient of friction. The influences of pressure variation and changes in pressure direction as the machining mode transitions from ductile to brittle are investigated based on resolved stresses on the identified active slip plane. The methodology proposed in this study can be extended to study other monocrystalline materials, and the findings can be utilized in the process planning of advanced optics manufacturing.