A cutting tool having a tool holder, cutting insert and clamping member. The tool holder includes an elongated supporting surface extending in a rearward-to-forward direction. The cutting insert has a central portion and three cutting portions, the central portion having two opposing side surfaces and three spaced apart locating surfaces defining a first imaginary triangle. The cutting insert is indexable about a central axis intersecting the two side surfaces. Each locating surface intersects two of three bisector planes containing the central axis and bisecting respective corners of the first imaginary triangle, and the cutting edge of each cutting portion is located entirely outside of the first imaginary triangle. In each index position the clamping member is located entirely rearward of a first vertical plane containing the central axis and perpendicular to the rearward-to-forward direction, and one of the locating surfaces is in clamping contact with the supporting surface.

A cutting insert according to one non-limiting example has a quadrangular prism shape extending from a front end toward a rear end along a central axis, and comprises a cutting portion, and a main body portion. The main body portion has an upper surface having a V-shaped flute extending along the central axis. An opening portion and a bottom portion of the flute each have a convex shape protruding upward in a direction along the central axis. A first flute has a first region positioned on the rear end side and a second region positioned on the front end side with respect to the first region. An opening angle of the first flute in the first region is smaller than an opening angle of the first flute in the second region.

A turning insert includes a top surface, an opposite bottom surface, and a reference plane therebetween. A center axis intersects the top and bottom surfaces and a side surface connects the top and bottom surfaces. A circular cutting edge is adjacent the top surface and the side surface. The top surface includes a set of first protrusions, which are elongated in a direction parallel to the adjacent cutting edge. A greatest distance from the reference plane to the first protrusions is greater than a distance from the reference plane to the cutting edge. The bottom surface has a set of radial grooves and includes a set of flat surfaces. The flat surfaces extend in a plane parallel to the reference plane, wherein in a top view each first protrusion is symmetrical in relation to a line extending between the center axis and a mid-point of the first protrusion.

A cutting insert, a holder, and a cutting tool with which the cutting insert can be easily and stably mounted on the holder and a fabrication target object can be excellently fabricated are provided. A cutting tool 100 that is used to fabricate a fabrication target object W by cutting includes a holder 50 and a cutting insert 10 that is mounted on a distal end of the holder 50. The holder 50 includes an insert pocket 53 into which the cutting insert 10 is fitted and a stopper portion 61 that elastically locks the cutting insert 10 to be fitted into the insert pocket 53. The cutting insert 10 includes a cutting portion 11 including a cutting edge 13, a fitting portion 12 that is fitted into the insert pocket 53, and a lock portion 21 that is formed at the fitting portion 12 and is to be locked to the stopper portion 61 of the holder 50.

A two-directional high-feed turning tool assembly includes a tool holder, a cutting insert and a clamping element securing the cutting insert to the tool holder. The cutting insert includes an active cutting edge having a centrally located forwardmost edge portion and first and second main edge portions extending rearwardly from the forwardmost edge portion, as well as sideways to an extent further than flank tool sides of the tool holder. The first and second main edge portions also can each have a relatively small immersion angle facilitating high-feed turning in two sideways directions.

A method to form a surface on a metal work piece includes providing a turning insert that has a nose angle formed between first and second cutting edges less than or equal to 85; providing a turning tool having a tool body with an insert seat in which the turning insert is mountable; arranging the orientation of the second cutting edge such that it forms a back clearance angle of more than 90 in a feed direction; rotating the metal work piece around a rotational axis in a first direction; moving the turning insert in a direction parallel to or at an angle less than 45 relative to the rotational axis; and setting the longitudinal axis of the tool body at an angle greater than zero but less than or equal to 90 relative to the rotational axis of the metal work piece.

A method to form a surface on a metal work piece includes providing a turning insert having a first cutting edge, a second cutting edge and a convex nose cutting edge connecting the first and second cutting edges, a nose angle formed between the first and second cutting edges being less than or equal to 85; arranging the second cutting edge such that it forms a back clearance angle of more than 90 in a feed direction; positioning all parts of the turning insert ahead of the nose cutting edge in the feed direction; rotating the metal work piece around a rotational axis in a first direction; and moving the turning insert in a direction parallel to or at an angle less than 45 relative to the rotational axis, such that the surface at least partly is formed by the nose cutting edge.

Provided is a cutting-edge replaceable cutting tool having a configuration capable of stably supporting a rotational moment acting on a cutting insert clamped on an insert mounting face of a body. It includes a cutting insert, a body including an insert mounting portion for removably mounting the cutting insert and a reception mechanism to receive the rotational moment acting on the cutting insert so as to rotate the cutting insert mounted on the insert mounting portion on a base surface, the mechanism including a first engagement portion formed on a lower surface of the cutting insert and a second engagement portion formed on the base surface of the insert mounting portion which is formed to engage with a specific portion of a surface defining the first engagement portion to receive the rotational moment.

A cutting tool having a tool holder, cutting insert and clamping member. The tool holder includes an elongated supporting surface extending in a rearward-to-forward direction. The cutting insert has a central portion and three cutting portions, the central portion having two opposing side surfaces and three spaced apart locating surfaces defining a first imaginary triangle. The cutting insert is indexable about a central axis intersecting the two side surfaces. Each locating surface intersects two of three bisector planes containing the central axis and bisecting respective corners of the first imaginary triangle, and the cutting edge of each cutting portion is located entirely outside of the first imaginary triangle. In each index position the clamping member is located entirely rearward of a first vertical plane containing the central axis and perpendicular to the rearward-to-forward direction, and one of the locating surfaces is in clamping contact with the supporting surface.

A turning insert includes a top surface, an opposite bottom surface, a reference plane located parallel to and between the top surface and the bottom surface, and a center axis extending perpendicular to the reference plane and intersecting the reference plane (RP), the top surface and the bottom surface. Side surfaces connect the top surface and the bottom surface. Three nose portions are formed symmetrically relative to the center axis. Each nose portion includes a first cutting edge, a second cutting edge and a convex nose cutting edge connecting the first) and second cutting edges. In a top view the first and second cutting edges on the same nose portion form a nose angle of 25-50 relative to each other. The distance from the first cutting edge to the reference plane varies in such a way that that this distance is decreasing at increasing distance from the nose cutting edge.