Patent ID: 7695222

Claim:
An indexable insert ( 1 ) comprising a substrate ( 8 ) and a coating layer ( 11 ) formed on the substrate ( 8 ), wherein the substrate ( 8 ) has at least one flank face ( 3 ) and at least one rake face ( 2 ), the flank face ( 3 ) and the rake face ( 2 ) are connected with an edge line ( 4 ) provided therebetween, the coating layer ( 11 ) includes an inner layer ( 12 ) including at least one layer and an outer layer ( 13 ) formed on the inner layer ( 12 ), the inner layer ( 12 ) includes an alumina layer or an alumna-containing layer serving as an outermost layer in contact with the outer layer ( 13 ), the outer layer ( 13 ) is composed of at least one metal selected from the group consisting of the periodic table group IVa elements, Va elements, and VIa elements, Al, and Si or a compound of at least one of the metals and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron, and the outer layer ( 13 ), in a portion involved in cutting, satisfies B/A≦0.9 wherein A μm is the average thickness on the flank face ( 3 ) side, and B μm is the average thickness on the rake face ( 2 ) side.