Effects of tool edge radius on ductile machining of silicon: An investigation by FEM

The submicron-level orthogonal cutting process of silicon has been investigated by the finite element approach, and the effects of tool edge radius on cutting force, cutting stress, temperature and chip formation were investigated. The results indicate that increasing the tool edge radius causes a significant increase in thrust force and a decrease in chip thickness. A hydrostatic pressure (∼15 GPa) is generated in the cutting region, which is sufficiently high to cause phase transformations in silicon. The volume of the material under high pressure increases with the edge radius. Temperature rise occurs intensively near the tool-chip interface while the highest cutting temperature (∼300 °C) is far lower than the necessary temperature for activating dislocations in silicon. As the edge radius is beyond a critical value (∼200 nm), the primary high-temperature zone shifts from the rake face side to the flank face side, causing a transition in the tool wear pattern from crater wear to flank wear. The simulation results from the present study could successfully explain existing experimental phenomena, and are helpful for optimizing tool geometry design in silicon machining.