抄録
Although Al2O3 ceramic tool shows an excellent performance in machining of FC (gray cast irons), it does not in machining of FCD (nodular cast irons). In this paper, cutting tests and reaction tests were conducted to find out the cause of the above phenomena. As a result of the cutting test, it was found that the matrix, carbon shape and hardness of the work material had little effects on the wear of the Al2O3 ceramic tool. And the difference in machinability of the two kinds of work material was presumed to be attributed to the reaction between tool and inclusions in work material. Therefore the reaction test was conducted between Al2O3 and MgO and the other oxide inclusions. As a result, it was found that MgO diffuses into Al2O3 ceramic tool and makes spinel called MgO·Al2O3, which decreases the wear resistance of the tool. Further, a new type of ceramic tool which was mainly made of carbides has been produced as a trial tool for FCD and its cutting performance was tested. The carbide ceramic tool showed twice as longer life than Al2O3 ceramic tool in machining of FCD.
