CEMENTED CARBIDE INSERT FOR TOUGHNESS DEMANDING SHORT HOLE DRILLING OPERATIONS

摘要

The present invention relates to a coated cutting insert with excellent toughness properties particularly useful for toughness demanding short hole drilling in low alloy and stainless steels and a method of making the same. The inserts comprise a substrate and a coating. The substrate consists of WC, 8-11 wt-% Co and 0.2-0.5 wt-% Cr with an average WC-grain size of 0.5-1.5 µm and a CW-ratio of 0.80-0.90. The coating comprises a laminar, multilayered structure of TiN+Ti<SUB>1-x</SUB> Al<SUB>x</SUB>N+TiN+Ti<SUB>1-x</SUB> Al<SUB>x</SUB>N+TiN. In polycrystalline, non-repetitive form, with x=0.4-0.ß with a thickness of the individual TiN- or Ti<SUB>1-x</SUB> Al<SUB>x</SUB>N-layers of 1-30 nm varying essentially at random and with a total thickness of the multilayered coating of 1-5 µm. The layers are deposited using arc evaporation technique.