The objectives of this research are 1) to develop the surface roughness prediction model in the turning process for the plain carbon steel with the coated carbide tool by utilizing the response surface analysis with the Box-Behnken design; 2) to investigate the effects of cutting parameters such as the cutting speed, the feed rate, the depth of cut and the tool nose radius on the surface roughness, the cutting force and the cutting temperature, and 3) to obtain the optimum cutting condition within the range of 3.125 micrometer Ra referring to JIS B0601(1982). The dynamometer and the infrared pyrometer are employed to measure the in-process cutting force and the in-process cutting temperature, respectively. The cutting force and the cutting temperature are measured to help analyze the relation between the surface roughness and the cutting conditions. However, the models of cutting force ratio and the cutting temperature are also proposed based on the experimental data.
The feed rate and the nose radius have more affected on the surface roughness as compared to the cutting speed and the depth of cut. The improvement of surface roughness is obtained from the decrement in the feed rate and the depth of cut, or an increment in the tool nose radius and the cutting speed. The developed surface roughness model can be effectively used to predict the surface roughness with the 95% confident interval. The optimum cutting condition referring to the minimum surface roughness is the cutting speed of 340 m/min at the feed rate of 0.15 mm/rev, the depth of cut of 0.2 mm and the tool nose radius of 1.2 mm.
