Recently, the reduction of tool cost in mechanical industry has become a serious consideration. Therefore, it is one of the most important subjects in machine shops to develop a tool having a long tool life. Boride-cermet tools are one of the prospective tools which meets such a requirement. However, there are few studies hitherto which deal with the cutting characteristics (wear mechanism) of boride-cermet tools. In the present-day situation, taking up the wear mechanism in rough cutting of S 45 C by the new boride-cermet tool as a subject of this paper, the authors examined such factors as cutting temperature, crater wear at rake face, and diffusion condition at interface between tool and chip. The formula for diffusion at the interface of tool and chip was introduced and diffusion density was also computed by the finite element method.
