Cutting insert for threading

A threading cutting insert in which a rake face is formed on an upper face, flanks as a cutting side face are formed between the upper face and a lower face opposing the upper face, and a plurality of tooth-shaped cutting edges are formed in a cross ridge line portion between the rake face and the flanks as viewed from an upper side of the rake face, wherein:

• the plurality of tooth-shaped cutting edges comprises at least one finishing cutting edge for transferring a shape of a screw, and at least one roughing cutting edge smaller than the finishing cutting edge as viewed from an upper side of the rake face,
• the flanks include a first flank having a first clearance angle, and a second flank having a second clearance angle larger than the first clearance angle, as the first and second flanks are viewed in a row direction of the plurality of tooth-shaped cutting edges, wherein the finishing cutting edge, the first flank, and the second flank are provided to be sequentially connected in that order from the upper face in a direction of the lower face,
• the first flank with its first clearance angle extends along a first cross ridge line portion formed at an intersection between the first flank and the rake face, the first cross ridge line portion extending along the entire finishing cutting edge, past a boundary portion between the finishing cutting edge and the roughing cutting edge, and along a trailing portion of the roughing cutting edge, and
• the second flank with its second clearance angle extends along a second cross ridge line portion formed at an intersection between the second flank and the rake face, the second cross ridge line portion extending along a crown portion of the roughing cutting edge, past the trailing portion of the roughing cutting edge in a feed direction (F) of the cutting insert.