US Patent 7090914 Coated cutting tool

A coated cutting tool with a hard coating layer formed on a substrate. The substrate comprises a binder phase and a hard phase. The coating layer comprises a smooth face having a surface roughness of 0.2 μm or less substantially at the blade-edge ridge and in a region which extends at least 200 μm from the rake face side boundary of the ridge toward the rake face side, and extends at least 50 μm from the flank side boundary of the ridge toward the flank side.