A single-sided three-way indexable milling insert for feed milling operations, includes a positive basic shape, a rake surface, a peripheral surface including side abutment surfaces, a base bearing surface and a screw hole connecting the rake and base bearing surfaces. The insert has a cutting edge including exactly three main cutting sub-edges and three secondary cutting sub-edges. 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.F?0.30.

A cutting insert having two opposing end surfaces, two identical opposing major side surfaces and two identical opposing minor side surfaces. Each end surface has four corners comprising two lowered corners and two raised corners, the two lowered corners being diagonally opposite each other, the two raised corners being diagonally opposite each other. The cutting insert also includes a major cutting edge formed at an intersection of each major edge and the end surface. A section of the major cutting edge proximate the raised corner constitutes a leading end of the major cutting edge, and a section of the major cutting edge proximate the lowered corner constitutes a trailing end of the major cutting edge. An angled margin only partially extends along the leading end of the major cutting edge and segments the major cutting edge.

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.

A cutting insert (1) comprises: a first end surface (2) and a second end surface (3) which are opposed to each other; a peripheral side surface (4) which extends so as to connect the first end surface (2) and the second end surface (3); a first cutting edge (5a) which is arranged in an intersecting edge between the first end surface (2) and the peripheral side surface (4); and a second cutting edge (5b) which is arranged in an intersecting edge between the second end surface (3) and the peripheral side surface (4). The peripheral side surface (4) includes a first flank (4a1) which is connected to the first cutting edge (5a) and an intermediate peripheral side surface portion (4b) which is arranged closer to the second end surface (3) than the first flank (4a1). The first flank (4a1) extends in a direction perpendicular to the first end surface (2). The intermediate peripheral side surface portion (4b) protrudes outward from the first flank (4a1).

An insert detachably attached to an indexable rotary cutting tool, having an upper surface having cutting edges along the ridgeline, a lower surface, side surfaces, and a center hole for a fastening screw; each cutting edge having a corner cutting edge formed in each acute corner portion, and a bottom cutting edge and a peripheral cutting edge formed along the ridgelines on both sides of the corner cutting edge; the bottom cutting edge and the peripheral cutting edge having different clearance angles; a flank of the corner cutting edge having an angle-changing surface portion having a clearance angle continuously changing in a region from the bottom cutting edge to the peripheral cutting edge; and the length of the peripheral cutting edge being restricted by a receding portion adjacent to an upper end of the peripheral cutting edge.

A milling tool includes a tool body having a front and a rear end between which an envelope surface extends. At least one insert seat having an outer border delimiting the insert seat from the front end and the envelope surface is provided. At least one double-sided cutting insert having an upper side, a lower side, an upper cutting edge and a lower cutting edge is radially mounted in the insert seat with the lower side abutting a bottom contact surface to provide an active upper cutting edge. In a direction of rotation of the tool body, at least a part of the lower cutting edge neighboring the outer border and located behind the active upper cutting edge, does not protrude by more than 0.5 mm from the outer border, and a distance between the part of the lower cutting edge and the outer border is smaller than 0.5 mm.

A rotary cutting tool has a plurality of circumferentially spaced grooves, each having a plurality of cutting inserts mounted. Each cutting insert has a wave-shaped major cutting edge, a corner cutting edge, and a minor cutting edge. The cutting inserts are arranged such that, the phases of the waves of the rotational trajectories formed by the cutting inserts that are adjacent to each other in a direction along the tool rotational axis coincide with each other in one groove. Also, the rotational trajectories of at least part of cutting edge portions of at least some cutting inserts are overlapped with each other in the direction of the tool rotational axis. Accordingly, even when the cutting edge portion is used as a major cutting edge and as an inner cutting edge, it is still possible to reduce cutting load and suppress breakage.

A reversible and indexable tangential milling insert includes two major surfaces and a peripheral surface which extends therebetween. The milling insert includes a mid-plane (M) located midway between the major surfaces, and an insert clamping bore with a central bore axis (H). The peripheral surface includes three side surfaces, each of which includes exactly two cutting portions, two relief portions and two minor abutment surfaces located on opposite sides of the mid-plane (M), each continuously extends between respective cutting portion and relief portion. Each cutting portion includes a major cutting edge, a minor cutting edge, and a corner cutting edge. In a cross section along a first imaginary plane perpendicular to the bore axis (H), each minor abutment surface is concavely curved, and on each side surface, the minor abutment surfaces converge outwardly.

A double-sided milling cutting insert has a first cutting edge disposed at an intersection of a top side and a side surface and a second cutting edge disposed at an intersection of a bottom side and the side surface. Each of the first and second cutting edges contains three cutting edge portions which are useable by indexing. The cutting edge portions each have a cutting corner, a main cutting edge adjacent to one side of the cutting corner, and a wiper edge adjacent to the other side of the cutting corner. The main cutting edge and the wiper edge are each inclined towards a reference plane with increasing distance from the cutting corner such that the first and second cutting edges have the largest distance to the reference plane in the regions of the cutting corners. The side surface has main clearance surfaces, secondary clearance surfaces, and curved corner surfaces.

According to the present disclosure, a cutting insert includes an upper surface having a polygonal shape and includes a corner, a side surface adjacent to the upper surface, a cutting edge and a protrusion. The cutting edge is located at a ridge part in which the upper surface intersects with the side surface and includes a corner part located at the corner. The protrusion is located on the upper surface. The protrusion includes a first protrusion on a bisector of the corner in a top view. The protrusion further includes a second protrusion adjacent to the first protrusion in a direction orthogonal to the bisector. The second protrusion is closer to the corner than the first protrusion in the top view.