A cutting insert has a cutting edge formed on part of an intersecting ridge line portion of an upper face or a lower face and a side face. The cutting edge includes a major cutting edge, a minor cutting edge, and a connecting cutting edge that connects the major cutting edge and the minor cutting edge. A minor cutting edge flank that is part of the side face and that corresponds to the minor cutting edge includes a first minor cutting edge flank that connects to the minor cutting edge and that has a clearance angle of 0°, and a second minor cutting edge flank that connects to the first minor cutting edge flank and that has a clearance angle of a negative value. A connecting cutting edge flank that is part of the side face and that corresponds to the connecting cutting edge includes a first connecting cutting edge flank that connects to the connecting cutting edge and that has a clearance angle of 0° or greater, and a second connecting cutting edge flank that connects to the first connecting cutting edge flank and has a clearance angle that is greater than the clearance angle of the first connecting cutting edge flank.

A cutting insert has a plate shape centered on an insert center axis. The cutting insert includes a front surface and a back surface facing an insert axial direction, an outer peripheral surface facing outward in an insert radial direction, and a cutting edge at an intersecting ridge line between the front surface and the outer peripheral surface. The back surface has a flat shape perpendicular to the insert center axis. The outer peripheral surface includes a flank surface coupled. The flank surface is inclined inward in the insert radial direction as extending in the insert axial direction from the front surface side to the back surface side. The front surface includes a rake surface. The rake surface is inclined from a back surface side to a front surface side in the insert axial direction as extending inward in the insert radial direction from the cutting edge.

The invention relates to a cutting insert having a polygonal upper side. Cutting edges, which are alternately configured as roughing cutting edges and finishing cutting edges, are provided at the edges of the upper side. The finishing cutting edges define an incircle (K1) having a diameter that is enlarged in comparison to a nominal size of the cutting insert, and the roughing cutting edges define an incircle (K2) having a diameter that is reduced in comparison to the nominal size of the cutting insert. The invention further relates to a cutting tool having a tool body on which at least one such cutting insert is disposed.

A single-sided four-way indexable cutting insert includes a positive basic shape, a rake surface, a peripheral surface including four side abutment surfaces, a base bearing surface and a screw hole connecting the rake and base bearing surfaces. The insert has an imaginary square frustum which defines a square base containing the cutting insert's base bearing surface, and further defines four isosceles trapezoid side surfaces respectively containing the cutting insert's four side abutment surfaces. A material volume V.sub.F of the cutting insert and a void volume V.sub.S of the insert fulfill the condition V.sub.S/V.sub.F0.25.

A cutting insert has a cutting edge formed on part of an intersecting ridge line portion of an upper face or a lower face and a side face. The cutting edge includes a major cutting edge, a minor cutting edge, and a connecting cutting edge that connects the major cutting edge and the minor cutting edge. A minor cutting edge flank that is part of the side face and that corresponds to the minor cutting edge includes a first minor cutting edge flank that connects to the minor cutting edge and that has a clearance angle of 0, and a second minor cutting edge flank that connects to the first minor cutting edge flank and that has a clearance angle of a negative value. A connecting cutting edge flank that is part of the side face and that corresponds to the connecting cutting edge includes a first connecting cutting edge flank that connects to the connecting cutting edge and that has a clearance angle of 0 or greater, and a second connecting cutting edge flank that connects to the first connecting cutting edge flank and has a clearance angle that is greater than the clearance angle of the first connecting cutting edge flank.

A single-sided four-way indexable cutting insert includes a positive basic shape, a rake surface, a peripheral surface including four side abutment surfaces, a base bearing surface and a screw hole connecting the rake and base bearing surfaces. The insert has an imaginary square frustum which defines a square base containing the cutting insert's base bearing surface, and further defines four isosceles trapezoid side surfaces respectively containing the cutting insert's four side abutment surfaces. A material volume V.sub.F of the cutting insert and a void volume V.sub.S of the insert fulfill the condition V.sub.S/V.sub.F0.25.

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.

The present invention provides a cutting insert in which suitable honing is formed on a cutting edge. The cutting insert is provided with: two end surfaces opposing each other; a peripheral side surface extending between the two end surfaces; and a cutting edge formed on an intersecting ridge between at least one of the two end surfaces and the peripheral side surface. The cutting edge at least includes a major cutting edge and an inner cutting edge. Honing is provided on the major cutting edge and the inner cutting edge. A width of second honing of the inner cutting edge is narrower than a width of first honing of the major cutting edge, as viewed from a side of the end surfaces.

A cutting insert (1) according to an embodiment has a lower surface (2), an upper surface (3), a side surface (4) disposed between the lower surface (2) and the upper surface (3), a pair of corner cutting edges (5) located along an intersection of the upper surface (3) and the side surface (4), and a major cutting edge (6) located between the pair of corner cutting edges (5). The major cutting edge (6) has a downwardly dented curvilinear part (61) and a pair of straight parts (62) respectively extending from the curvilinear part (61) toward the pair of corner cutting edges (5) in a side view. A portion (6p) of the curvilinear part (61) located lowermost is close to one corner cutting edge (5b) in the side view.

An insert includes a first part and a second part. The first part includes a first surface, a second surface, and a plurality of side surfaces located between the first surface and the second surface. The second part includes a third surface, a fourth surface, and a first cutting edge. The third surface is located between the side surfaces and located from a side of the first surface to a side of the second surface. The fourth surface is located between the side surfaces and adjacent to the third surface. The first cutting edge is located along at least a part of a ridge line of the third surface and the fourth surface. The first cutting edge is inclined in a front view of the third surface, and the first cutting edge has a convex curvilinear shape in a front view of the fourth surface.