Development of Laser-Assisted Machining of Yttria-Stabilized Tetragonal Zirconia Polycrystal

Abstract

Yttria-stabilized tetragonal zirconia polycrystal is promising ceramic for artificial implants despite its difficult-to-cut feature. Thus, a machining method that enhances the process performance is required. We proposed UV laser-assisted machining of Y-TZP. In the process, the laser beam is utilized to ablate the material as well as to heat it. First, the optimal wavelength of the laser was determined by considering the fluence threshold for the ablation. In order to obtain the fluence threshold, we measured the absorption coefficient of Y-TZP against optical beam with various wavelength, and also experimentally determined the energy density required to induce the ablation. From the discussion regarding the optimal wavelength, we decided to adopt the wavelength of 355 nm. A series of the laser assisted machining were performed on Y-TZP to evaluate the machinability. During the experiments, specific cutting force, surface roughness and tool wear were evaluated. The results revealed that the specific cutting force reduced by approx. 60 % at maximum, the surface roughness was also reduced and the tool wear was suppressed in the proposed method.