US Patent 7241082 Double-sided cutting insert and milling cutter

A double-sided cutting insert, for use in a milling cutter, having two identical opposing end surfaces and two opposing identical major side surfaces with a through bore extending between, and opening out to, the major side surfaces. Major cutting edges are formed at the intersection of each major side surface with each end surface. Adjacent each major cutting edge, in each major side surface, is a primary relief surface. In each cross section of the cutting insert taken in a plane generally perpendicular to the major side surfaces, a line tangent to the primary relief surface at the major cutting edge is inclined to a median plane of the cutting insert at an acute interior angle.