| 摘要 |
PROBLEM TO BE SOLVED: To provide a cutting edge without generating any chipping (micro defect) while performing an excellent cutting performance in a long period even in the case for applying the high speed cutting and the high heavy cutting such as high feed and deep cut steel or cast iron. SOLUTION: This tool is composed by evaporating chemically or physically a hard quality covered layer by one sort or two or more sorts of hard quality covered layers including an Al2 O3 layer, such as a Ti compound layer consisting of TiO layer, TiN layer, TiCN layer, TiO2 layer, TiCO layer, TiNO layer, and TiCNO layer, and an Al2 O3 layer, at an average layer thickness of 8 to 25μm. In this case, the Al2 O3 layer to compose the hard quality covered layer is composed of the Al2 O3 layers having different crystal compositions, at the upper side and the lower side (base body side). That is, the above upper side is composed of an Al2 O3 layer having a parallel aggregate formation of a longitudinal growth of columnar single polyhedron crystal uniforming the section form and section size in the longitudinal direction neighboring each other, while the above lower side is composed of an Al2 O3 layer having a parallel aggregate formation of a longitudiral growth of columnar various polyhedron crystal having a large difference in the section form and the section size in the longitudinal direction neighboring each other.
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