Patent ID: 7422805

Claim:
A cutting tool insert for machining of bimetal bodies comprising cast iron and aluminium and/or magnesium alloys under wet conditions at moderate cutting speeds, said cutting tool comprising a cemented carbide body and a coating, wherein said cemented carbide body includes a substrate with the following composition: WC, 9-11 wt-% Co and suitable amount of conventional grain refiner(s) to obtain an average WC grain size of<1 μm, and wherein said coating comprises: a first, innermost layer of TiC x N y O z with x+y+z1, y>x and z<0.2, with equiaxed grains with size <0.5 μm and a total thickness of 0.1-1.5 μm, a layer of TiC x N y with x+y=1, x>0.3 and y>O.3, with a thickness of 1-4 μm with columnar grains with an average diameter of <5 μm, a layer of a smooth, fine-grained, 0.5-2 μm κ-Al 2 O 3 with a thickness of 1-2.5 μm, and an outer layer of TiN with a thickness of <1 μm, wherein the outermost TiN-layer is reduced in thickness along the cutting edge.