Patent ID: RE39986

Claim:
A cutting tool insert comprising: a cemented carbide body comprising 6-15 weight % Co, 0.2-1.8 weight % cubic carbides of Ti, Ta, Nb or any combination thereof, a highly W-alloyed binder phase with a CW-ratio of 0.78-0.93, and the balance WC; and a coating comprising a first innermost layer of TiC x N y O z wherein x+y+z=1, the first layer having a thickness of 0.1-1.5 μm and equiaxed grains with size <0.5 μm, a second layer of TiC x N y O z wherein x+y+z=1, the second layer having a thickness of 0.4-3.9 μm, with columnar grains with an average diameter of 0.1-5.0 μm, a third layer of a smooth fine-grained κ—Al 2 O 3 layer with a thickness of 0.5-5.5 μm, and a total thickness of the first innermost TiC x N y O z and the second TiC x N y O z layer is 0.5-4.0 μm, and the total thickness of all layers is 2.0-6.0 μm.