Modeling the size effect in ultra-precision machining by mechanism-based strain gradient crystal plasticity

In ultra-precision machining, indentation and/or burnishing by the tool-edge of cutting tool occurs. This gives rise to complex elastic and plastic deformation in the machining surface such as materials swelling which is found to be pronounced when the depth cut is small. The size effect observed in ultra-precision machining with a depth of cut from 100 nm and above is simulated by the micro-scratching experiment of FCC single crystals based on the mechanism-based strain gradient crystal plasticity (MSG-CP). The size effect in mico-scratching of an FCC single crystal is studied by measuring the ratio of the thrust force to the projected area of contact between the cutting tool and the work-piece by varying the depth of scratching at the submicron scale. The simulation results demonstrate the effectiveness of the MSG-CP model in studying the scale dependent problems in ultra-precision machining.