Research on Ductile Regime Milling of Fully Sintered Dental Zirconia

The feasibility and performance of ductile regime milling were investigated based on experiments to improve the machining quality and to reduce machining cost of fully sintering dental Zirconia. The formula about the relation between milling depth and other cutting parameters was derived based on condition of little cutting output, while theoretical critical cutting depth of ductile-brittle transition was estimated according to energy method. A series of milling experiments in different cutting depths were conducted on above basis. The practical critical cutting depth of ductile-brittle transition of ceramics was found through scanning the surface of specimens representing different milling depths by SEM. The principle of ductile-brittle transition of ceramics milling was illustrated by theories of stress equispaced effect and gliding based on the results of experiments. The performance of ductile regime milling was studied according to the measurement and analysis of cutting force, cutting temperature, surface roughness and residual stress. Results of the performance show that ductile regime milling of ceramics is feasible and can achieve high quality of machining.