Abstract: In a cutting tool, if the outermost ceramic coating layer is a ?-Al2O3 coating layer, then certain microns of the ?-Al2O3 layer will be transformed into an ?-Al2O3 by instantaneous melting, vaporization and solidification. Further, if the outermost coating layer of the ceramic coating layers is an ?-Al2O3 coating layer, then the surface roughness will be enhanced since at least a portion of it will be melted, wherein the melted surface will be solidified with its surface flattened by the surface tension provided in a melted state.

Abstract: A method of a pre-treatment process for coating notably improves both the surface roughness of a coating layer of a cemented carbide cutting tool and the bonding force of the coating layer to the substrate. According to the method, a sintered surface layer within a range of 0.5-5 ?m, which corresponds to the tungsten carbide particle size of a substrate, is properly removed from the substrate surface of a cemented carbide cutting tool. Thus, a porous sintered surface layer having a non-uniform structure is removed and a substrate surface having high structure density and evenness is provided compared to blasting pre-treatment. In order to obtain a sufficient bonding force between a coating layer and the substrate, the surface ratio of open pores, which exist around tungsten carbide particles appearing by removal of the porous sintered surface, is equal to or more than 5%.

Abstract: A surface treatment method can perform coated surface treatment on a cutting edge R and a rake surface, while maintaining a radius of curvature of the cutting edge R and uniformly surface-treating the rake surface. The surface treatment method includes providing an opening chamfered at corners adjacent to an upper surface of the fixture to the fixture for fixing a coated cutting insert; fixing the coated cutting insert inside the opening in such a manner that a rake surface of the coated cutting insert is disposed lower than upper surfaces of the fixture but higher than a lower edge created on the opening of the fixture by the chamfering; and conducting the surface treatment on a cutting edge R and the rake surface of the coated cutting insert.

Abstract: A method of a pre-treatment process for coating notably improves both the surface roughness of a coating layer of a cemented carbide cutting tool and the bonding force of the coating layer to the substrate. According to the method, a sintered surface layer within a range of 0.5-5 ?m, which corresponds to the tungsten carbide particle size of a substrate, is properly removed from the substrate surface of a cemented carbide cutting tool. Thus, a porous sintered surface layer having a non-uniform structure is removed and a substrate surface having high structure density and evenness is provided compared to blasting pre-treatment. In order to obtain a sufficient bonding force between a coating layer and the substrate, the surface ratio of open pores, which exist around tungsten carbide particles appearing by removal of the porous sintered surface, is equal to or more than 5%.

Abstract: A surface treatment method can perform coated surface treatment on a cutting edge R and a rake surface, while maintaining a radius of curvature of the cutting edge R and uniformly surface-treating the rake surface. The surface treatment method includes providing an opening chamfered at comers adjacent to an upper surface of the fixture to the fixture for fixing a coated cutting insert; fixing the coated cutting insert inside the opening in such a manner that a rake surface of the coated cutting insert is disposed lower than upper surfaces of the fixture but higher than a lower edge created on the opening of the fixture by the chamfering; and conducting the surface treatment on a cutting edge R and the rake surface of the coated cutting insert.

Abstract: In a cutting tool, if the outermost ceramic coating layer is a ?-Al2O3 coating layer, then certain microns of the ?-Al2O3 layer will be transformed into an ?-Al2O3 by instantaneous melting, vaporization and solidification. Further, if the outermost coating layer of the ceramic coating layers is an ?-Al2O3 coating layer, then the surface roughness will be enhanced since at least a portion of it will be melted, wherein the melted surface will be solidified with its surface flattened by the surface tension provided in a melted state.