US Patent 7838132 PVD-coated cutting tool insert

The present invention relates to a coated cutting tool insert of cemented carbide with coating including at least one layer of Ti1-x AlxN deposited by PVD-technique. The layer has x=0.4-0.6 with a compressive residual stress of >4-6 GPa and a thickness of 1.5-5, preferably 2.5-4 μm. Both the I(111) and I(200) are <7.5, preferably <5, times, the intensity average noise level. Good adhesion despite high compressive stress is obtained if the layer is deposited by cathodic arc evaporation technique at a bias in the range −90<U<−50V, preferably −80V<U<−60V.