US Patent 7799413 Coated cutting tool insert

A CVD-coated cutting tool insert with improved toughness properties having the ability to withstand high temperatures without sacrificing edge line security is disclosed. The insert coating comprises a TiCxNy-layer with a low tensile stress level of 50-500 MPa and an α-Al2O3-layer with a high surface smoothness with a mean Ra<0.12 μm as measured by AFM-technique, obtained by subjecting the coating to an intensive wet blasting operation.