US Patent 7704593 Cutting tool and method of producing the same

A cutting tool having coating layers which are formed on the cutting tool substrate made of hard material, and the coating layers are composed of an inner layer of AlTiN, an interlayer of TiN, and an outer layer of Al2O3. The cutting tool is preferably produced by subjecting its substrate to surface-cleaning and surface treating by projection of flexible abrasives before forming the coating layers. The total thickness of the coating layer on a flank of the cutting tool is preferably in the range of 2 to 80 μm, and, further, it is preferable that thicknesses of the inner layer, the interlayer, and the outer layer on the flank are 0.5 to 35 μm, 1.0 to 40 μm, and 0.5 to 5 μm, respectively.