A cutting insert in the present disclosure includes an upper surface, a lower surface, a side surface, and an edge. The upper surface includes a first corner part and a second corner part. The edge is located in a region which is located between the first corner part and the second corner part. The edge includes a first edge located at a side of the first corner part, a second edge located at a side of the second corner part, and a third edge located between the first edge and the second edge. The edge has a curvilinear shape being recessed toward the lower surface in a side view. Each of a radius of curvature R1 of the first edge and a radius of curvature R2 of the second edge is smaller than a radius of curvature R3 of the third edge in a side view.

An object is to prolong the life of a cubic boron nitride cutting tool used for cutting a heat-resistant alloy. A cubic boron nitride cutting tool includes an edge tip made of a sintered cubic boron nitride compact including cubic boron nitride particles; and a base metal that holds the edge tip at a corner portion of the base metal, wherein a cutting edge formed on the edge tip of the tool has a positive rake angle.

A cutting insert of one aspect includes a top surface including a corner portion and a pair of side portions each adjacent to the corner portion, a bottom surface, a side surface located between the top surface and the bottom surface, and a corner cutting edge disposed at the corner portion. In such a cutting insert, the top surface includes a first rake surface located along the corner cutting edge, a raised portion located farther on the inner side than the first rake surface, and a second rake surface located between the corner cutting edge and the raised portion. Moreover, a rake angle at a first region of the second rake surface corresponding to a center of the corner cutting edge is greater than a rake angle at a second region of the second rake surface located beside the first region.

A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, the coating layer comprising a first laminate structure and a second laminate structure, wherein: the first laminate structure has a laminate structure in which predetermined compound layers of two kinds, each having a different composition, are laminated in an alternating manner; the first laminate structure satisfies a predetermined condition; the second laminate structure has a laminate structure in which a first compound layer comprising a predetermined oxide and/or oxynitride and a second compound layer having a predetermined composition are laminated in an alternating manner; and an average thickness of each compound layer which constitutes the first laminate structure, an average thickness of each compound layer which constitutes the second laminate structure, and a thickness of the coating layer in its entirety each fall within a predetermined range.

A cutting insert for high-efficiency cutting is disclosed. The cutting insert includes an upper surface (110a), a lower surface (HOb), side surfaces (114) and corner side surfaces (116), which connect the side surfaces to each other. A circular opening is formed through the central portions of the upper and lower surfaces. In the cutting insert, cutting edges are formed by respective junctions between one of the upper and lower surfaces and the side surfaces and between one of the upper and lower surfaces and the corner side surfaces. The cutting edges comprise three corner cutting edges (122), six major cutting edges (124), which extend from opposite ends of the corner cutting edges towards the neighbor corner cutting edges, and three minor cutting edges (126), which are connected between the major cutting edges. Furthermore, the cutting edges may be formed on both the upper surface and the lower surface.

A cutting tool includes a cutting edge member. The cutting edge member forms a corner portion. The cutting edge member includes a cutting edge formed at the intersection of a rake surface and a flank, at least two breaker wall surfaces and at least one convex portion. The cutting edge includes a first cutting edge and a second cutting edge connected thereto. The second cutting edge is situated at the corner portion. Each breaker wall surface is formed to extend along the cutting edge. The convex portion is formed between the two breaker wall surfaces spaced from each other to protrude relatively toward the cutting edge side. A part of the convex portion is situated around a connecting portion of the first and second cutting edges.

Chip discharge during high-feed machining and low-feed machining particularly in a high-depth-of-cut state or the like is improved so as to provide adaptability to a wide range of cutting conditions during low depth and high depth cutting and during low-feed and high-feed machining and allow so-called freedom of feed during cutting to be improved. A cutting insert includes a cutting edge body and a substrate to which the cutting edge body is joined. The cutting edge body has a prismatic shape having a longitudinal direction and a lateral direction perpendicular to the longitudinal direction and includes a cutting edge formed on an intersecting edge between a peripheral side surface and an upper surface of the cutting edge body having the prismatic shape and a recessed part formed at a position on the upper surface of the cutting edge body which is more distant from the intersecting edge than from the cutting edge. The substrate has a projected part upwardly projecting from the upper surface of the cutting edge body.

A cutting insert is used in a cutting edge replaceable rotary cutting tool. The cutting insert includes a first cutting edge formed on an intersecting ridge portion between a first end surface of two opposite end surfaces and a circumferential side surface, and a first depressed portion formed along a part of the first cutting edge. The first depressed portion is provided to form a larger rake angle at the first cutting edge than that at a part not having the first depressed portion of the first cutting edge.

An object is to prolong the life of a cubic boron nitride cutting tool used for cutting a heat-resistant alloy. A cubic boron nitride cutting tool includes an edge tip made of a sintered cubic boron nitride compact having a thermal conductivity within the range of 20 to 70 W/m.Math.K and including cubic boron nitride particles having an average particle diameter within the range of 0.5 m to 2 m; and a base metal that holds the edge tip at a corner portion of the base metal, wherein a cutting edge formed on the edge tip of the tool has a positive rake angle.

The present disclosure relates to a quadrangular indexable drill insert. The drill insert includes a substantially flat top surface, a bottom surface and a side surface adjoining the top and bottom surfaces. The side surface comprises four identical cutting edges intersecting the top surface; each cutting edge comprises a first part edge oriented inwardly towards axis of the drill body. A second part edge tangential to an imaginary inscribed circle diameter connected to the first part edge through a convex curve. A third part connected to the second part edge through concave curve and a fourth part edge connected to the third part edge though a convex curve. The insert further includes a curved nose portion at four corners, each adjoining a first part edge of one cutting edge with a fourth part edge of a succeeding cutting edge.