Patent ID: 8137795

Claim:
An indexable insert comprising a substrate and a coating layer formed on the substrate, wherein the substrate has at least one flank face and at least one rake face, the flank face and the rake face are connected to each other with an edge line therebetween, the coating layer includes an inner layer constituted by one or more layers and an outer layer formed on the inner layer, the innermost layer constituting the inner layer in contact with the substrate is composed of a compound containing at least one element selected from the group consisting of Group IVa elements, Group Va elements, and Group VIa elements in the periodic table, and Al and Si; and at least one element selected from the group consisting of carbon, nitrogen, oxygen, and boron, and the uppermost layer of the inner layer in contact with the outer layer is composed of a compound at least containing Ti and at least one of nitrogen and boron, and excluding carbon, and the layer other than the innermost layer and the uppermost layer is composed of a compound containing at least one element selected from the group consisting of Group IVa elements, Group Va elements, and Group VIa elements in the periodic table, and Al and Si; and carbon or a combination of carbon and at least one element selected from the group consisting of nitrogen, oxygen, and boron, the outer layer is constituted by an alumina layer or an alumina-containing layer, and in a region involved in cutting, the outer layer satisfies B/A≦0.9 where A μm is the average thickness at the flank face side and B μm is the average thickness at the rake face side, wherein a compressive stress of the rake face is larger than the compressive stress of the flank face.