US Patent RE39884 Coated milling insert and method of making it

A coated milling insert particularly useful for milling in low and medium alloyed steels with or without raw surface zones during wet or dry conditions. The insert is characterized by a WC-Co cemented carbide with a low content of cubic carbides and a highly W alloyed binder phase and a coating including an inner layer of TiCxNyOz with columnar grains, a layer of κ-Al2O3 and, preferably, a top layer of TiN. The layers are deposited by using CVD methods.