Smoothed particle hydrodynamics (SPH) simulation and experimental investigation on the diamond fly-cutting milling of zirconia ceramics

This paper presents a more efficient ultra-precision diamond fly-cutting method to achieve the damage-free surface machining of hard-brittle zirconia ceramics at one time instead of the traditional abrasive-based processes. Firstly, the smoothed particle hydrodynamics (SPH) cutting simulation model of zirconia ceramics is established in LS-DYNA based on JH-2 constitutive model. The radial diamond fly-cutting milling experiments of zirconia ceramics are carried out on the three-axis ultra-precision machine tool, and the correctness of SPH simulation model is verified by the brittle-ductile transition (BDT) depth and chip morphology. Then, the effects of tool geometry and cutting parameters on stress distribution, brittle-ductile transition depth, cutting force characteristics, and chip morphology are investigated by the proposed model. Some conclusions are given as follows: the tool with more negative rake angle are benefit for hydrostatic pressure and getting greater brittle-ductile transition depth; the critical brittle-ductile transition depths of zirconia ceramics under -15 degree and -35 degree tool rake angle are 0.8μm and 1μm, respectively. Finally, by controlling the maximum undeformed chip thickness below 1μm, an application experiment is carried out and a crack-free nanometer-level surface is achieved in the axial diamond fly-cutting milling of zirconia ceramics.