A cutting insert includes a rake end surface having four corners and, in a center thereof, a central surface portion. A supporting end surface has four corners and, in a center thereof, a central supporting surface portion. A peripheral side surface extends between the rake end surface and the supporting end surface. The peripheral side surface includes two opposing major side surfaces. A hole extends through the cutting insert from one of the major side surfaces to the other of the major side surfaces, wherein the central surface portion is disposed at a greater distance from a central axis (A) of the hole than is the central supporting surface portion. The single-sided cutting insert has a corner radii or cutting edge radii that extend over at least a quarter of a width of the cutting insert.

A cutting tool assembly for milling a rail top, includes a first section and a second section mounted to the first section. Each section includes a plurality of insert-receiving pockets for receiving a plurality of different types of cutting inserts. The plurality of different types of cutting inserts are arranged in a plurality of helical teeth that may be separated by a helical chip flute. In one embodiment, a first type of cutting insert is formed with a radius, R, a second type of cutting insert is formed with a radius, R1, and a third type of cutting insert is formed with a radius, R2, to perform a milling operation on three different areas of the rail top.

A round double-sided cutting insert includes an insert peripheral surface that includes a plurality of angularly spaced apart indexing latches protruding therefrom and a plurality of cylindrical insert side abutment surfaces that circumferentially alternate with the plurality of indexing latches. An insert holder has a pocket peripheral surface which includes at least one indexing gap and a plurality of pocket side abutment surfaces that circumferentially alternate with the at least one indexing gap. When the cutting insert is releasably attached to the insert holder, to constitute a fastened position of a cutting tool, each of the plurality of pocket side abutment surfaces abuts a respective insert side abutment surface and each indexing gap has a respective indexing latch located therein.

A cutting insert of one aspect includes a first face, a second face, and a third face. The first face includes a first side, a second side, and a first corner. The first face includes a land face connected to the third face. The land face includes a first land face connected to the first corner, a second land face, and a third land face. The first land face includes a first region connected to the second land face and a second region connected to the third land face. When the first face is viewed from the front, a second width of the second region is larger than a first width of the first region in a front view of the first face.

A cutting insert includes a main body including a first face, a second face, and a third face. The second face includes a rake face. Among the outer-peripheral sides of the second face, the boundary portion with the first face is a main cutting edge. When viewed from the side where the first face is disposed, the main cutting edge includes a first straight portion, a second straight portion, and a curved portion. The first straight portion is located adjacent to a reference side. The second straight portion is arranged at a distance from the first straight portion. The curved portion connects the first straight portion and the second straight portion. A first intersection angle of the first straight portion with respect to the reference side is different from a second intersection angle of the second straight portion with respect to the reference side.

An indexable cutting insert has opposing upper and lower end surfaces, and a peripheral surface including three side surfaces circumferentially alternating with three corner surfaces. The three side surfaces define an imaginary triangle and an imaginary hexagon. Each corner surface intersects the upper end surface to form an upper corner peripheral edge having a primary cutting edge. In a top view, each triangle side traverses two upper corner peripheral edges, imaginary lines tangential to the end points of each primary cutting edge are either collinear or form an obtuse angle greater than 175 degrees, each primary cutting edge has a primary length greater than half the hexagon side length, and at least one triangle side traverses each primary cutting edge. The insert is removably secured in a rotary cutting tool such that one of the upper corner peripheral edges contains an axially forwardmost point of the insert's upper peripheral edge.

A cutting insert mounted on a rotating tool including a body that rotates about a predetermined rotational axis. The cutting insert includes an upper surface, a lower surface and a peripheral side surface. The cutting insert further includes an inner cutting edge and a corner cutting edge. A top part, which has the maximum distance from the lower surface, is located on the corner cutting edge.

Provided is a cutting insert capable of suppressing edge fracture when a work having high hardness is machined. A cutting insert includes two end surfaces having a plurality of corner parts and opposed to each other, a peripheral side surface extending between the two end surfaces, and a cutting edge formed at an intersecting edge between at least one of the two end surfaces and the peripheral side surface. The cutting edge has at least a first corner edge, a second corner edge, a major cutting edge, and an end cutting edge. The end cutting edge has a circular-arc shape, which projects outward, as viewed from the side of the end surface. The end cutting edge has a width which is from 15% to 50% of the width of the cutting insert. The end cutting edge has an arc radius which is from to 1/1 of the width of the cutting insert.

This cutting insert is provided with a lower surface of polygonal shape including side parts and a pair of corner parts, an upper surface, a lateral surface situated between the lower surface and the upper surface, a pair of corner cutting edges located at the pair of corners, and a main cutting edge located in a side portion. The main cutting edge is upwardly convex in shape, and in side view includes an upwardly convex curving portion, and a pair of linear portions respectively extending toward the pair of corner cutting edges from the curving portion. The top portion of the curving portion is positioned more toward the one of the corner cutting edges which, of the pair of corner cutting edges, is that contiguous to a working surface of a work material during cutting of the work material.

A cutting insert of an embodiment includes an upper surface including a first upper cutting edge and a second upper cutting edge, a lower surface including a first lower cutting edge and a second lower cutting edge, and a side surface. The side surface includes a first surface extending from the second upper cutting edge, a second surface extending from the first lower cutting edge, a third surface extending from the first upper cutting edge, and a fourth surface extending from the second lower cutting edge. The first surface and the fourth surface are parallel to a central axis. The second surface is inclined so as to depart from the central axis as going from the lower surface toward the upper surface. The third surface is inclined so as to depart from the central axis as going from the upper surface toward the lower surface.