Patent ID: 8215879

Claim:
A method for machining of steel or stainless steel, comprising: providing a cutting tool insert formed from a cemented carbide substrate having a coercivity of about 10-15 kA/m and a coating, the coating comprising a first (innermost) layer of Ti 1-x Al x N with about 0.25≦x≦about 0.7 with columnar grains and a total thickness of about 0.5-5 μm, and a layer of (Al 1-y Cr y ) 2 O 3 with about 0.1≦y≦about 0.6 with a thickness of about 1-5 μm with columnar grains; and cutting with the cutting tool insert at a cutting speed of about 75-600 m/min with an average feed, per tooth in the case of milling, of about 0.08-0.5 mm.