In an embodiment, a cutting insert includes an upper surface, a one or more side surfaces, and a cutting edge. The upper surface includes a first corner portion, and a first side that is adjacent to the first corner portion. The one or more side surfaces are adjacent to the upper surface. The cutting edge is disposed on at least a portion of a section where the upper surface and the side surfaces intersect. When viewed from directly above, the cutting edge includes first, second, third and fourth cutting edges. The first cutting edge is disposed at the first corner portion and has a convex curved shape. The second cutting edge is next to the first cutting edge, and has a linear shape. The third cutting edge is next to the second cutting edge, and has a convex curved shape. The fourth cutting edge is next to the third cutting edge on the first side.

A coated cutting tool includes a substrate having a rake side, a clearance side and a cutting edge and a coating comprising a first layer and a second layer. The second layer has a sandwich structure of an inner layer, an intermediate layer and an outer layer, wherein the inner layer is exposed through an opening in the outer layer, the opening extending over at least a portion of the width of the cutting edge. Thereby, a double layer is provided in critical areas, whereas a single layer is provided in other areas. The double oxide layer is an aluminum oxide layer. A method for manufacturing the coated cutting tool is also provided.

A cutting insert for threading of the present invention includes two opposing end surfaces and a peripheral side surface extending therebetween. The peripheral side surface has a first side surface portion and a second side surface portion arranged at different positions in a circumferential direction. A cutting edge is formed at an intersecting ridgeline portion between the first end surface and the first side surface portion and at least a portion of this cutting edge has a shape corresponding to a thread groove. The second side surface portion has an inclined portion which enlarges outward from the side of the first end surface toward the side of the second end surface. This inclined portion is configured to engage with a side wall surface of a tool body so as to prevent floating of the cutting insert.

A method for forming a stand-alone wafer or a coating on a substrate uses a composite of cubic boron nitride (cBN) particles and other materials, such as nitrides, carbides, carbonitrides, borides, oxides, and metallic phase materials. The wafer or coating may be formed of a thickness up to about 1000 microns for improved wear life. The density of material within the wafer or coating may be varied according to desired parameters, and a gradient of particle sizes for the cBN may be presented across the thickness of the material.

A cutting insert (1) includes a top surface (6), a side surface, a rake face (10) on the top surface (6), a front flank face (11) and a lateral flank face (12), a cutting edge (9) including a front cutting edge (13), and a lateral cutting edge (14), a breaker groove (15) adjacent to the front cutting edge (13) and the lateral cutting edge (14), and a rake face end (20). The breaker groove (15) includes a descending surface (16) and an ascending surface (17). The ascending surface (17) includes a front wall surface (21) and a lateral wall surface (22) on the side of the front cutting edge (13) and the side of the lateral cutting edge (14). An opening angle (1) of the front wall surface (21) is greater than an opening angle (2) of the lateral wall surface (22) in the top surface (6) view.

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 cutting tool formed by a coating layer on a substrate has cutting edges that feature serrations. The linear dimensions of the serrations may vary from a few nanometers up to 10 microns. The serrations result in a smoother cut edge on the workpiece, particularly when the workpiece is formed of certain materials that are seen as particularly difficult to cut, such as hardened steels.

A cutting insert has a bottom supporting surface, a center cutting edge, two secondary cutting edges, realized on both sides of the center cutting edge and offset in relation to the center cutting edge, and two transition edges connecting the center cutting edge to the secondary cutting edge adjacent in each case. The two secondary cutting edges are realized in each case vertically offset and, where applicable, also offset in depth with respect to the center cutting edge and are laterally spaced from the center cutting edge. The transition edges, in each case in a non-edge-overlapping region, have at least over a portion an inclination n where 2n20 in relation to a height direction which extends at right angles with respect to a main extension plane of the supporting surface.

The present invention relates to a cutting insert having a cutting edge which is provided with a corner section that forms a convex arc shape when seen in a planar view from the direction facing the rake face and a pair of linear sections that are in contact with the corner section at the both ends thereof. The cutting edge is provided with a first region along the corner section, a second region along the linear section and a third region positioned between them, and a cross-sectional area of the insert main body on a cross-section orthogonal to the cutting edge in a range of width which is a radius R (mm) of the corner section is made largest in the third region, smallest in second region and between them in the first region in terms of size.

The invention suppresses chipping of a cutting edge of a cutting tool while maintaining sharpness of the cutting edge.

[Solution] A coating (20) of a replaceable knife (10) of the cutting tool is formed so that either one of a rake-face coating portion (22) that coats a rake face (14) or a clearance-face coating portion (24) that coats a clearance face (16) becomes thicker than the other. The film thickness of the thicker coating portion (22, 24) is set in a range of 0.5 m to 15.0 m, and a ratio of the film thickness of the thinner coating portion (24, 22) to the film thickness of the thicker coating portion (22, 24) is set in a range of 0.01 to 0.15.