A cutting tool insert includes eight identical cutting edges. Each separate cutting edge has a first cutting edge portion and a second cutting edge portion. A corner angle between the first cutting edge portion and the second cutting edge portion is within a range of 75 to <90 degrees. The first cutting edge portion and the second cutting edge portion have substantially the same length to provide a substantially equal cutting depth. As seen along the center axis of the insert a first angle within a range of 14+/−9 degrees is formed between a first imaginary line extending from the center axis to a corner point at the first side surface and a second imaginary line extending from the center axis to an adjacent corner point at the second side surface. A cutting tool insert holder is also disclosed.

An indexable cutting insert is suitable for vertical and oblique machining. The cutting insert has top and bottom surfaces, first to fourth side surfaces extending between the top and bottom surfaces, and a screw hole passing through the top and bottom surfaces. The top surface has a mounting surface of a flat surface. The top and bottom surfaces are rotationally symmetric with each other. A cutting edge is formed at a junction between the top surface and the adjacent first and second side surfaces. A non-cutting edge is formed at a junction between the top surface and the adjacent third and fourth side surfaces. The first and second side surfaces form an acute angle with a plane extending from the mounting surface of the top surface. The third and fourth side surfaces form an obtuse angle with the plane extending from the mounting surface of the top surface.

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.

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.

A toolholder includes a bottom abutment surface, a projection extending upwardly from the bottom abutment surface, the projection including an internally threaded opening, having a central axis that is offset from a central axis of the projection in a first direction, and a clamping screw having external threads for mating with threads of the internally threaded opening and a head having a bottom clamping surface shaped as a truncated cone for contacting an insert clamping surface and urging an insert substantially in a first direction when the clamping screw is tightened relative to the toolholder and the insert. The toolholder also includes at least one abutment member extending from a side wall of the projection in a radial direction, each abutment member having an abutment point, at least which is closer to the central axis of the projection than to the central axis of the internally threaded opening.

In a cutting tool having an indexable cutting insert with three cutting portions, the cutting insert is removably securable to an insert holder by means of a fastener. The cutting insert has two opposing end surfaces with a peripheral side surface extending therebetween. At least one end surface has a central boss protruding therefrom with a raised support surface, and the peripheral side surface has three abutment recesses. In an end view of the cutting insert, each of the three abutment recesses is visible and located inside a first imaginary circle circumscribing the visible central boss. A holding portion of the insert holder has a seating surface with at least one protuberance protruding therefrom. The support surface is in clamping contact with the seating surface, and exactly two of the three abutment recesses are engaged with the at least one protuberance.

A cutting tool assembly includes a cutting tool and an indexable cutting insert having an insert index axis. The cutting insert includes parallel insert first and second sides connected by an insert peripheral surface that extends peripherally around the cutting insert. At least one clamping hole opens out to one or both of the insert first and second sides, and at least a portion of the clamping hole is in a clamping region of the cutting insert. The insert peripheral surface includes cutting edges that are spaced-apart and extend from the insert first side to the insert second side. Along a width direction, which is perpendicular to the insert first and second sides, each of the cutting edges is wider than the cutting insert, at least at the cutting region of the cutting insert.

A toolholder and method for use with a cutting insert having a clamping opening, comprising a toolholder body and a clamp pivotably mounted to and contacting the toolholder body and pivotable between a first position in which a protrusion of the clamp is disposed in a position in which it is arranged to be received in the clamping opening in the cutting insert to secure the cutting insert to the toolholder body and a second position in which the protrusion is spaced, relative to the toolholder, upwardly from the first position so that the cutting insert is not secured to the toolholder body by the protrusion. A resilient member is arranged relative to the clamp to urge the clamp to the first position and to resist pivoting of the clamp to the second position. An opening in the clamp may receive a portion of a separate lever.

A tool, a toolholder and a tool-toolholder unit obtained by coupling tool and toolholder is adapted to be fixed to a rotor of a shredder. The tool and the toolholder have a coupling mechanism that permit a quick and easy assembly or disassembly of the two elements and ensure, at the same time, a stable and safe fixing during use of the tool.