The effect of TiC coating layer on the tool life was studied. Commercial WC insert tool(P20) was coated with TiC by Chemical Vapor Deposition(C.V.D.) method. The wear land and the maximum crater depth of the WC insert tool and the TiC coated insert tool were measured at given time intervals. By observing the crater region of the TiC coated insert tool during wear development, the effect of the TiC coating layer on the crater was studied. Tool life equations were derived from the cutting data.
It was shown that the tool life of the TiC coated insert tool was about 5 times that of WC insert tool for the case of cutting speed 150 m/min and feed rate 0.4 mm/rev and it increased to approximately 20 times for the higher speed(250 m/min) and feed rate 0.4 mm/rev. It was shown that the cutting speed of TiC coated insert tool was about 1.8 times that of WC insert tool for the cutting with the same tool life. It was observed that the coating layer still remained at the bottom of the crater after the developed crater depth was deeper than the coating thickness and it seemed to act as a lubricant and a diffusion barrier preventing transfer of cobalt to the friction surface. When the coating layer was totally removed from the crater surface, the wear rate increased but at a slower rate than for uncoated WC insert tool due to the presence of the TiC coating layer at the boundary of the crater.
