Patent ID: 8101291

Claim:
Coated cutting tool insert comprising a cemented carbide insert body with a stratified binder phase enriched surface zone and a coating wherein the stratified binder phase enriched surface zone has a binder phase content having a maximum of from about 1.5 to about 4 times the nominal binder phase content and is from about 15 to about 45 μm thick whereby the stratified binder phase enriched surface zone as well as an about 100 to about 300 μm thick zone underneath it containing no free graphite, which corresponds to a C-porosity of C00 and with a C-porosity in the inner central part of the cemented carbide body of from about C06 to about C08, the inserts are large with an iC, inscribed circle diameter, of greater than or equal to about 19 mm, and a thickness of greater than or equal to about 6 mm, and the inserts have edge rounding about 35 to about 95 μm.