Numerical assessment of transition in cutting mode and its effect on roughness creation

Ductile-to-brittle transition in cutting mode is an important phenomenon in the ultra-precision machining and surface finish of brittle materials. Using a newly-developed coarse-grained molecular dynamics technique, we systematically explore the effect of depth of cut on the cutting mode and the evolution of roughness. Our simulations demonstrate that the transitional depth of cut (TDoC) model accurately predicts the material removal mechanisms, which are affected by both the material's properties and the cutting depth. When the cutting depth increases, the operating mechanism shifts from shearing-induced serrated chip formation to cleavage-cracking chip breakage. The RMS roughness study demonstrates that the roughness is a direct outcome of the chip formation mechanism and is, in general, higher when chip breakage occurs.