Experimental study of the thermal effects and processing in CW laser-assisted turning of SiC ceramics

In order to realize plastic processing in the continuous-wave laser-assisted machining (LAM) of SiC ceramics, the thermal effect of the laser and the influence of preheating the surface morphology and the laser power on the roughness of the machined surface are investigated. A three-dimensional transient heat transfer model is established and confirmed to be accurate with a maximum error in the surface reference temperature of 10.8%. Furthermore, the oxidation and ablation behavior of the SiC ceramics is investigated via temperature field simulations and laser preheating experiments to determine the critical temperature (1650 degrees C) for ablation of the machined surface. The most suitable cutting depth is then determined to be between the ablation depth and the softening depth. The surface morphology of the machined surface is also investigated by varying the laser power to determine the three processing states and corresponding laser power ranges, namely, brittleness (0-185 W), plasticity (185-225 W), and thermal damage (> 225 W). The surface roughness first decreases and then increases, and the corresponding maximum (1.298 mu m) and minimum (0.45 mu m) values are obtained at a laser power of 0 and 215 W, respectively. The plastic turning of SiC ceramics provides theoretical guidance for the turning of other hard and brittle materials.