A cutting insert according to an embodiment of the present disclosure relates to a circular double-sided cutting insert including a top surface, a bottom surface, a lateral surface, and a cutting edge, and mounted to a cutting tool, in which a plurality of clearance surfaces and a plurality of fastening surfaces are located on the lateral surface, and among the plurality of fastening surfaces, a fastening surface, which is brought into contact with the cutting tool upon mounting of the cutting insert to the cutting tool, forms an acute angle with respect to the top surface or the bottom surface acting as a rake surface.

A cutting insert for a rotary cutting tool has a second surface that includes a second seating surface having a shape of a flat surface. The first cutting edge has a first main cutting edge portion and a first sub cutting edge portion. The second cutting edge has a second main cutting edge portion and a second sub cutting edge portion. When viewed in a direction from the first surface toward the second surface, at least a portion of the second sub cutting edge portion is located outside the first main cutting edge portion, and at least a portion of the first sub cutting edge portion is located outside the second main cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first sub cutting edge portion and the second sub cutting edge portion has a shape of a curved line.

A double-ended parting cutting insert. The cutting insert includes two cutting portions at opposite ends thereof which are oriented at 90° to each other. The cutting insert includes a pair of rake and support engagement grooves, the rake and support engagement grooves of each one of the pair converging in a direction away from a respective cutting portion. An insert holder includes a clamping portion having a resilient upper clamping jaw having an upper engagement ridge and a lower base jaw having a lower engagement ridge. A gap therebetween forms an insert receiving slot that has a slot opening. The upper and lower engagement ridges converge in a direction away from the slot opening. When the cutting insert is releasably attached to the insert holder, to constitute a fastened position of a cutting tool, the cutting insert is located in the insert receiving slot and resiliently clamped therein.

What is presented is a cutting insert including a polygonal plate-shaped insert main body that includes: two polygonal surfaces; a side surface; and a cutting edge, the insert main body has a mounting hole that is centered on an insert center line passing through centers of the two polygonal surfaces, the cutting edge includes a major cutting edge extending from a first end of a corner edge located at a corner of the polygonal surface, and, in the opening of the mounting hole, a plurality of protrusions protruding with respect to a boss surface around an opening of the mounting hole are formed at intervals in a peripheral direction in an inner periphery side region of the major cutting edge.

A cutting insert includes first and second polygonal surfaces and a plurality of side surfaces. A corner edge that has a corner rake surface on the first polygonal surface is formed at a first corner portion, and a main cutting edge is formed from the corner edge to a second corner portion. The main cutting edge includes, at least on a corner edge side, a rake angle gradual increase region where a rake angle of a main rake surface gradually increases to a positive angle side as going from a first end portion of the corner edge toward a second corner portion side.

A cutting insert for a rotary cutting tool has a second surface that includes a second seating surface having a shape of a flat surface. The first cutting edge has a first main cutting edge portion and a first sub cutting edge portion. The second cutting edge has a second main cutting edge portion and a second sub cutting edge portion. When viewed in a direction from the first surface toward the second surface, at least a portion of the second sub cutting edge portion is located outside the first main cutting edge portion, and at least a portion of the first sub cutting edge portion is located outside the second main cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first sub cutting edge portion and the second sub cutting edge portion has a shape of a curved line.

A cutting insert has an upper surface, a lower surface and a lateral surface. The upper surface has a first upper side, and a second upper side. The lower surface has a first lower side and a second lower side. The lateral surface has a first lateral surface, a second lateral surface, and a third lateral surface. The first lateral surface has a first concave part having a first constraining surface having a flat shape. The second lateral surface has a second concave part having a second constraining surface having a flat shape. The third lateral surface has a convex part. The first concave part and the second concave part are separated from each other by the convex part.

A tool body has base and clamping jaws which are spaced apart by a clamping recess. The clamping jaw is resiliently movable with respect to the base jaw. The clamping recess includes an insert receiving pocket and a clamping flexibility recess extending from the insert receiving pocket. The clamping jaw includes a flexible overhanging clamping portion, and a fixed clamping portion connected by a hinge clamping portion, the flexible overhanging clamping portion being delimited by the insert receiving pocket and a clamping flexibility recess. The clamping recess comprises an innermost clamping recess point which is located at the clamping flexibility recess.