US Patent 7104736 Tangential cutting insert and milling cutter

A tangential cutting insert having two identical opposing end surfaces with two identical opposing major side surfaces and two identical opposing minor side surfaces extending between them. Each end surface has a peripheral edge containing cutting edges and four corners of which two are lowered and two are raised. Each end surface is provided with at least one projecting abutment member having a projecting abutment surface, wherein in a side view of either major side surface, the at least one projecting abutment surface is concave.