Patent ID: 8177460

Claim:
A cutting insert ( 22 ) having a polygonal shape, the cutting insert ( 22 ) comprising: two opposing end surfaces ( 28 ) and a peripheral surface ( 34 ) extending therebetween, with a median plane (M) located between the end surfaces ( 28 ) bisecting the cutting insert ( 22 ); a through bore ( 36 ) extending between the end surfaces ( 28 ); a cutting edge formed at the intersection of each end surface ( 28 ) with the peripheral surface ( 34 ), the cutting edge being divided into identical cutting sections ( 40 ), each cutting section being located between two vertexes ( 38 ) of the polygonal shape, each cutting edge section comprising a primary cutting edge ( 42 ) and a secondary cutting edge ( 44 ) that merge together; an insert tangential abutment surface ( 50 ) located between the cutting edge and the through bore ( 36 ); wherein a primary relief surface ( 52 ) in the peripheral surface extends from each primary cutting edge and forms an insert internal obtuse angle (α) with a first reference plane (P 1 ) that passes through the primary cutting edge and is parallel to the median plane (M); a secondary relief surface ( 54 ) in the peripheral surface extends from each secondary cutting edge and forms an insert internal acute angle (β) with a second reference plane (P 2 ) that passes through the secondary cutting edge and is parallel to the median plane (M); and each primary cutting edge has a first curved shape and each secondary cutting edge has a second curved shape, in a side view of the cutting insert.