Patent ID: RE41972

Claim:
A cutting tool insert made of cemented carbide, titanium based carbonitride or ceramics having an improved resistance to smearing of the workpiece material on the cutting edge comprising a body of generally polygonal or round shape having an upper face, an opposite face and at least one clearance face intersecting said upper and lower faces to define a cutting edge, said insert being at least partly coated with at least two refractory layers of which one is a fine-grained α-Al 2 O 3 -layer and the other is an MeC x N y O z -layer where Me is a metal selected from the group consisting of the metals in the Groups IVB, VB and VIB of the Periodic Table and (x+y+z)=1, said Al 2 O 3 -layer being the top layer along the cutting edge-line and on the upper face and said MeC x N y O z -layer being the top layer on the clearance face.