Patent ID: 8672590

Claim:
A cutting insert comprising a substrate having a seat recessed from a top surface of the substrate at a corner of the substrate and a superhard sintered body bonded to the seat, a cutting edge, a rake face, and a chip breaker being formed in the superhard sintered body, wherein the chip breaker includes, in a plan view of the insert, a projection that projects from a line that crosses a bisector of the corner toward a tip end of an arc edge of the cutting edge; a first breaker wall formed between a top edge of the projection and the rake face; and a second breaker wall formed between a first ridge line that extends from a base end of the projection to a side surface of the superhard sintered body and the rake face, wherein the rake face has a positive rake angle, wherein a second ridge line formed between the rake face and the side surface of the superhard sintered body is inclined such that a distance to a bottom surface of the substrate decreases as a distance from the cutting edge increases, and wherein the second ridge line does not extend along the cutting edge.