| abstract |
A multilayer coated cutting tool comprising a cemented carbide body with at least one sintered-on inlay containing polycrystalline cubic boron nitride forming at least one cutting edge. Reduced crater wear of the rake face of the tool is achieved by reducing chemical interaction between tool and workpiece/chip material, and used edges of indexable inserts can be readily identified. The tool is provided with a multilayer coating by thermal CVD, the coating including (1) a first, innermost, layer of TiCxNyOz with x+y+z=1, with y>x and z<0.2, with equiaxed grains with size <0.5 mu m and a total thickness <1.5 mu m, (2) a second layer of TiCxNyOz with x+y+z=1, preferably with z=0, x>0.3, most preferably x>0.5, having a thickness of 1-8 mu m, with columnar grains, and (3) a third layer of a smooth, fine-grained (grain size about 1 mu m) layer of ( alpha -Al2O3 or kappa -Al2O3 or mixtures thereof, with a thickness of 2-10 mu m. |