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 stump cutter bit for use with a stump cutting apparatus of the type utilizing a cutting wheel or drum rotated about a rotational axis wherein the cutting tool is attached to the cutting wheel or drum. The cutting tool supports the stump cutter bit. The cutting bit having a front face including a plurality of surfaces including an outer surface, an inner surface, and in intermediate surface located between the outer and inner surface.

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 substantially parallelogramatic insert having a downward inclined main cutting edge and an auxiliary cutting edge in part of a long-side ridgeline and a short-side ridgeline adjacent to a pair of corner cutting edges of an upper surface; the main cutting edge being constituted by first to third straight cutting edges; the first to third straight cutting edges being connected in a bent-line shape with inward obtuse crossing angles when viewed from above, such that the second straight cutting edge is positioned outermost; and cutting edge angles .sub.1, .sub.2, .sub.3 between the rake faces and flanks of the first to third straight cutting edges meeting the relation of .sub.1>.sub.2>.sub.3.

Provided is an insert for being mounted on a tool holder. The insert includes three substantially right-angled corners along a perimeter, a main cutting edge, a sub cutting edge, and a flat lower surface. A clearance angle of a second end main side surface forms an obtuse angle with respect to a lower surface, and a clearance angle of a second end sub side surface forms an obtuse angle with respect to the lower surface. A clearance angle of a first end main side surface forms a right angle with respect to the lower surface, and a clearance angle of a first end sub side surface forms a right angle with respect to the lower surface.

A reversible cutting insert for milling has first and second cutting edges formed at the transitions from the top and bottom surfaces to a lateral face. The cutting insert has a 4-fold rotational symmetry. A reference plane extends perpendicular to the axis of symmetry. The cutting edges have four cutting edge portions. One cutting edge portion is a main edge and a wiper edge that are connected by a rounded cutting corner. The first and second cutting edges are at the greatest distance from the reference plane in the region of the cutting corners. Main and wiper clearance faces directly adjoin an assigned main edge and wiper edge, respectively, in the circumferential lateral face. Exterior angles between the main clearance faces and the reference plane are greater than exterior angles between the wiper clearance faces and the reference plane.

A polygonal cutting has opposing first and second end surfaces connected by a side surface, and a plurality of cutting edges formed between the end surfaces and the side surface. Each cutting edge is formed at corner and includes a corner cutting edge and a major cutting edge connected to the corner cutting edge. A rake surface formed along the cutting edge on first the end surface is inclined toward the second end surface. In a side view of the cutting insert, the major cutting edge includes an inclined part which is inclined so as to approach the second end surface from the corner cutting edge. A portion of the rake surface along the inclined part is formed such that an angle of inclination toward the second end surface increases toward the corner in a direction along the intersecting edge between the first end surface and the side surface.

A double-sided, indexable, non-positive ramping insert has a 180-degree rotational symmetry about each of the first, second and third axes of a three-dimensional Euclidean space. The ramping insert includes two first surfaces and an insert peripheral surface which extends therebetween. The ramping insert includes four cutting portions, each includes a major cutting edge, a wiper edge connected transversely thereto via a corner cutting edge and a ramping edge which extends transversely from the wiper edge in a view parallel to the first axis. Each peripheral surface includes four non-positive ramping relief surfaces, each of which extends from a respective ramping edge towards, and not beyond, a first median plane which is defined by the second and third axes.

A double-sided, indexable, non-positive ramping insert has a 180-degree rotational symmetry about each of the first, second and third axes of a three-dimensional Euclidean space. The ramping insert includes two first surfaces and an insert peripheral surface which extends therebetween. The ramping insert includes four cutting portions, each includes a major cutting edge, a wiper edge connected transversely thereto via a corner cutting edge and a ramping edge which extends transversely from the wiper edge in a view parallel to the first axis. Each peripheral surface includes four non-positive ramping relief surfaces, each of which extends from a respective ramping edge towards, and not beyond, a first median plane which is defined by the second and third axes.