CUTTING INSERT AND MANUFACTURING METHOD THEREFOR

摘要

Provided is a cutting insert in which a hard sintered-body blade material is used for a surface that contributes to cutting. The radius of a nose R part is 0.4-2.4mm, and the apex angle α of the nose R part is 50-95 degrees. The rake angle β of the apex angle of the nose R part at a bisected cross-section position is 1-10 degrees. A chamfer provided to a cutting edge part is an unequal width negative land. The width of the negative land, at least on one side of the negative land from the boundary at the apex of a nose R part cutting blade, gradually decreases from the apex of the nose R part cutting blade towards a position at which the nose R part cutting blade connects to a straight line cutting blade. The width of the negative land at the apex of the nose R part cutting blade is W1 and the width of the negative land at both ends of the nose R part cutting blade is W2, and W1 is 0.04-0.2mm and the ratio of W1 to W2 is at least 1.5.