Patent ID: 8419319

Claim:
A cutting insert comprising a cutting edge formed at a ridge between an upper surface and a side surface, a high-positioned portion located at one end of the ridge; and a low-positioned portion located lower in a thickness direction of the insert main body than the high-positioned portion, and located at the other end of the ridge, wherein the cutting edge comprises; a first flat cutting edge having substantially the same height as the high-positioned portion; a second flat cutting edge having substantially the same height as the low-positioned portion; and a tilted cutting edge having a height decreasing from the high-positioned portion toward the low-positioned portion, and located between the first flat cutting edge and the second flat cutting edge, wherein the side surface has a plurality of grooves extending from the side surface to the upper surface to divide the cutting edge, a first flank connecting to the first flat cutting edge, a second flank connecting to the tilted cutting edge and a third flank connecting to the second flat cutting edge, and a clearance angle within each of the grooves increases from one end of the cutting edge toward the other end of the cutting edge, and the first flank and the third flank comprise clamping surfaces located on substantially coplanar surfaces, respectively, and the second flank is configured to project from the first flank and the third flank.