Patent ID: 7897247

Claim:
A cutting tool insert comprising a coating and a cemented carbide body, said cemented carbide body comprises from about 5 to about 9 wt-% Co, and from about 1 to about 5 wt-% cubic carbides of the metals Ta and Nb, the Ti content in the composition corresponding to technical impurity, and balance WC of from about 86 to about 94 wt-%, said body having a coercivity of from about 19.5 to about 24.5 kA/m, and said coating comprises a first innermost layer of TiC x N y O z with x+y+z=1 and y>x and z is less than about 0.1 with a thickness of from about 0.1 to about 2 μm, and with equiaxed grains with size is less than about 0.5 μm, a layer of TiC x N y O z where x+y+z=1, with a thickness of more than about 10 to about 15 μm, with columnar grains, a layer of TiC x N y O z where x+y+z=1, z is less than about 0.5 and x>y with a thickness of from about 0.1 to about 2 μm and with equiaxed or plate-like grains with size less than about 0.5 μm, a layer of smooth, fine-grained, textured α-Al 2 O 3 with a thickness from about 3 to about 8 μm, and a grain size of from about 0.5 to about 2 μm, an outer layer of a multilayered structure of TiN+TiC in one or several sequences with TiC being the outermost layer and a total thickness of from about 0.5 to about 2 μm, the outer coating layer being removed in the edge line and on the rake face so that the Al 2 O 3 layer is on top along the cutting edge line and on the rake face and the outer TiC layer is the top layer on the flank face.