In a cutting tool having an indexable lay-down cutting insert with a central body portion and three circumferentially spaced apart cutting portions, the cutting insert is removably secured to an elongated holding portion of an insert holder. Each cutting portion has a cutting edge with first and second cutting end points, the cutting edge formed at the intersection of an upward facing rake surface and a radially outward facing relief surface. In a top view of the cutting insert, parallel imaginary first and second vertical planes containing the first and second cutting end points, intersect the central body portion at first and second body side points, which are located first and second cutting distances from the first and second cutting end points, respectively. Each of the first and second cutting distances is greater than twenty-five percent of the first radius of an imaginary first circle circumscribing the cutting insert.

An undersized indexable cutting insert being devoid of a through bore and has exactly three main cutting edges. The cutting insert has an inscribed circle which tangentially contacts only and all main cutting edges, and has an inscribed circle diameter of under 3.8 millimeters.

An indexable cutting insert, arranged for being mounted in an insert seat of a tool body of a shoulder milling tool, includes a triangular top surface, a triangular bottom surface, and three circumferential surfaces extending between the top and bottom surface. On each side of the cutting insert an individual one of the three circumferential surfaces extends along an edge of the triangular top surface and along an edge of the triangular bottom surface. The cutting insert includes at each of the top and bottom surfaces three cutting corners, three main cutting edges and three minor cutting edges. Each cutting corner connects a main cutting edge and a minor cutting edge. Each of the cutting corners, each of the main cutting edges and each of the minor cutting edges are provided at an intersection between the top surface or the bottom surface and one of the circumferential surface.

A cutting insert includes a first end surface and a second end surface, in which a first peripheral side surface includes a first rake surface adjacent to a first main cutting edge and a first concave surface connected to the second end surface and formed to be recessed from the first rake surface toward a central axis of a through hole, and the first concave surface has a first restraint surface provided at a position where a distance between the first restraint surface and a second main cutting edge is smaller than a distance between the central axis of the through hole and the second main cutting edge, when viewed from a direction parallel to the central axis of the through hole.

A cutting insert of an embodiment of the present invention includes an upper surface, a lower surface, a side surface connected to each of the upper surface and the lower surface, and an upper cutting edge located at an intersection of the upper surface and the side surface. The lower surface includes a mount part having alternately three first top portions spaced a distance a away from a central axis extending between the upper and lower surfaces and three second top portions spaced a distance b away from the central axis in a bottom view. The mount part further has a concave part including at least the central axis. The second top portions are located closer to the upper surface than the first top portions. A cutting tool with the cutting insert, and a method of manufacturing a machined product by using the cutting tool are also provided.

The objective of the present invention is to provide a cutting insert which reduces cutting load and can be accurately positioned at a coupling part of a cutting tool even if cutting edges are broken or deformed. To this end, the cutting insert of the present invention includes an upper surface, a lower surface, a plurality of lateral surfaces connecting the upper surface with the lower surface, and a plurality of upper cutting edges formed between the plurality of lateral surfaces and the upper surface. In addition, the cutting insert coupled with the coupling part of the cutting tool includes: first and second upper cutting load reducing portions formed on the upper surface and provided at each side coming in contact with first and second upper cutting edges of the plurality of upper cutting edges facing each other so as to reduce the cutting load; and a one side position setting portion provided on a first lateral surface of the plurality of lateral surfaces not coming in contact with the first and second upper cutting edges so as to set the position of the cutting insert in the coupling part.

A cutting insert and a shoulder milling tool are disclosed. The cutting insert includes a surface-wiping secondary cutting edge inclined in relation to a median plane of the cutting insert such that a distance to the median plane decreases in a direction toward a corner cutting edge. The corner cutting edge, as seen in a side view along the median plane and towards a main cutting edge, has a concave curve.

A cutting insert may include a base including a first surface, a second surface and a lateral surface. The first surface may include a first corner, a second corner and a first side. The first side may include a first portion, a second portion, a third portion and a fourth portion in this order in a direction from the first corner to the second corner. An imaginary straight line being in contact with the first portion may be a reference line in a front view of the first surface. Inclination angles of the first portion, the second portion, the third portion and the fourth portion relative to the reference line may be respectively a first angle, a second angle, a third angle and a fourth angle. The third angle may be smaller than each of the second angle and the fourth angle.

Provided is a cutting insert configured to be able to realize downsizing of a cutting tool. A cutting insert includes: an upper surface and a lower surface facing each other and having a plurality of corner parts; a side surface connecting the upper surface and the lower surface and forming intersecting edges with the upper surface and the lower surface, respectively; and a through hole that has a central axis extending from the upper surface to the lower surface and that is formed for penetration from the upper surface to the lower surface. A corner cutting edge arranged at a position corresponding to a corner part of the upper surface, a minor cutting edge connected to a first end of the corner cutting edge, and a major cutting edge connected to a second end of the corner cutting edge are formed on the intersecting edge between the upper surface and the side surface. A flank of the corner cutting edge and a recessed part located on the lower surface side of the flank of the corner cutting edge are formed on the side surface.