PURPOSE: To improve the peeling resistance and breakage resistance of a film by limiting the thickness of the aluminum oxide film near a ridge line and at the center section of a face, and unifying the film thickness.
CONSTITUTION: Surfaces of a polyhedron base is coated with an aluminum oxide film to form a coated member. The thickness of the aluminum oxide film at a ridge line section up to 100μm toward the center section of a face from a ridge line is set to 0.5-6.5μm, and the thickness of the aluminum oxide film at the center section of the face is set to 0.5-5.0μm. The ratio of the thickness of the aluminum oxide film at the ridge line section against the thickness of the aluminum oxide film at the center section is set to 1.0-1.3. When this cutting tool is practically used, it has excellent peeling resistance of the film and excellent breakage resistance as a coated member, and the tool life is better by about two times or more than the conventional coated member.
UEKI MITSUO
SUZUKI HISASHI
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