Thread turning cutting insert having a cutting portion with three cutting teeth and cutting tool

A thread turning cutting insert (22) having an insert central axis (C) and comprising:

• opposite insert upper and lower surfaces (28, 30) and an insert peripheral surface (32) extending therebetween about the insert central axis (C);
• and
• at least one thread cutting portion (52) comprising:
• three spaced apart, non-identical cutting teeth (54A, 54B, 54C) which differ from one another in shape and/or size, the three cutting teeth (54A, 54B, 54C) protruding outwardly from the insert peripheral surface (32) in a common tooth protruding direction (TD), the three cutting teeth (54A, 54B, 54C) being arranged sequentially along a teeth arrangement axis (A) which defines a teeth arrangement direction (AD) and comprising a roughing tooth (54A), a finishing tooth (54C) and a semi-finishing tooth (54B) located therebetween, the roughing tooth (54A) being forward of the semi-finishing tooth (54B) and the semi-finishing tooth (54B) being forward of the finishing tooth (54C) with respect to the teeth arrangement direction (AD);
• three cutting edges (58) formed at the intersection of the insert upper surface (28) and the insert peripheral surface (32), each cutting edge (58) being located on a respective cutting tooth (54A, 54B, 54C);
• a chip forming groove (70) recessed in the insert upper surface (28), the chip forming groove (70) extending along a groove axis (G) and comprising opposite near-flank and far-flank groove surfaces (72A, 72B) which converge towards each other, the near-flank groove surface (72A) being closer to the three cutting teeth (54A, 54B, 54C) than the far-flank groove surface (72B);
• and
• three planar land surfaces (76), each extending from an entire length of a respective cutting edge (58) to the near-flank groove surface (72A), thereby defining a land border line (78).