These inserts are made with a black alumina ceramic on the cutting edges. Compared to carbide inserts, ceramic lasts longer in hardened-steel and cast iron tooling applications because it is chemically inert and has better heat resistance. Ceramic inserts have comparable wear resistance to cubic. KATO Tangless and tanged CoilThread inserts are helically-coiled fastening devices that provide permanent, wear-resistant threads, exceeding the strength of most parent materials. Among them, the inner sleeve is made of ceramic ring structure, used to contact with the shaft sleeve, the outer sleeve is metal material, used to connect with. Composition: An advanced Alumina/TiC black ceramic grade. Application: Great combination of toughness and wear resistance; used for machining alloy steels, tool steels, and stainless steels to 60 HRC (653 HB). 5mm solid sleeves and special size solid sleeve. They have a hardness of 2,100-2,500 HV (About 40% above carbide), which enables them to machine Hard Steel up to 55 HRC.