Patent ID: 7754316

Claim:
A coated cutting tool insert of cemented carbide comprising a body of generally polygonal or round shape having at least one rake face and at least one clearance face, said insert having a composition of from about 8.5 to about 11.5 wt-% Co, from about 6 to about 10 wt-% cubic carbonitrides, balance WC, a CW-ratio in the range from about 0.77 to about 0.90, and a surface zone of a thickness of from about 11 to about 35 μm, depleted of cubic carbonitride phase, said insert being at least partly coated with a from about 10 to about 25 μm thick coating including at least one layer of TiC x N y , where x≧0, y≧0 and x+y=1, and an α-Al 2 O 3 layer being the outer layer at least on the rake face and on said at least one rake face; the TiC x N y layer has a thickness of from about 5 to about 15 μm and a tensile stress level of from about 50 to about 390 MPa; the α-Al 2 O 3 layer has a thickness of from about 3 to about 12 μm and is the outermost layer with an XRD-diffraction intensity ratio I(012)/I(024) is greater than or equal to about 1.3 and with a mean Ra value MRa less than or equal to about 0.12 μm at least in the chip contact zone on the rake face, as measured on ten randomly selected areas 10×10 μm 2 by AFM-technique and on said clearance face; the TiC x N y layer has a tensile stress in the range from about 500 to about 700 MPa; the α-Al 2 O 3 layer has an XRD-diffraction intensity ratio I(012)/I(024) less than about 1.5; or on said at least one rake face and said at least one clearance side; the TiC x N y layer has a thickness of from about 5 to about 15 μm and a tensile stress level of from about 50 to about 390 MPa; the α-Al 2 O 3 layer has a thickness of from about 3 to about 12 μm, an XRD-diffraction intensity ratio I(012)/I(024) greater than or equal to about 1.3, and on the rake face is the outermost layer with a mean Ra value MRa less than or equal to about 0.12 μm at least in the chip contact zone on the rake face, as measured on ten randomly selected areas 10×10 μm 2 by AFM-technique and on that said clearance face the top layer comprises a colored heat resistant paint or a colored PVD layer.