The disclosure relates to a cutting insert for a tool for machining a workpiece, comprising: two identical mutually opposite base surfaces, wherein at least a part of each base surface is orthogonal to a z-axis of the cutting insert, two identical mutually opposite main side surfaces which extend between the two base surfaces, wherein at least a part of each main side surface is oriented orthogonally to an x-axis of the cutting insert, and two identical mutually opposite secondary side surfaces which extend between the two base surfaces, wherein at least a part of each secondary side surface is oriented orthogonally to a y-axis of the cutting insert, wherein the x-, y- and z-axes are main axes of the cutting insert that are oriented orthogonally to one another, wherein between each one of the base surfaces and each one of the main side surfaces a main cutting edge is arranged, and wherein each main side surface has two diagonally opposite first segmental cutting edges, wherein each first segmental cutting edge adjoins a first end of the respective main cutting edge, wherein the main cutting edges and the first segmental cutting edges of each main side surface are each located in a cutting edge plane which extends orthogonally to the x-axis, wherein the first segmental cutting edges are each arranged on a first protrusion which is arranged on each of the secondary side surfaces and defines a first clearance angle.

A cutting insert and a cutting tool having same. The cutting insert includes: an upper surface; a lower surface having a flat surface; a fastening hole penetrating the upper surface and the lower surface; side surfaces each connecting to the upper surface and the lower surface; and cutting edges formed by the upper surface and the side surfaces. A first cutting edge is inclined downward. A major side surface comprises a first major side surface connected to the upper surface so as to constitute the first cutting edge, and a second major side surface connected to the first major side surface and the lower surface. A minor side surface comprises a first minor side surface connected to the upper surface so as to constitute a second cutting edge, and a third minor side surface connected to the upper surface and the lower surface.

A double-sided cutting insert that has a positive clearance face and includes a top portion, a bottom portion substantially identical to the top portion, and a middle portion. The inscribed diameter at the middle portion is larger than the inscribed diameter at each of the top portion and the bottom portion. The double-sided cutting insert having positive clearance face provides a simplified grinding method in order to achieve the dimensional precision required as well as reduced tooling cost allowing both positive and negative double-sided cutting inserts seat in the same insert-receiving pocket on the same tool holder.

An insert in which a cutting edge is formed only between an upper surface and a side surface. The insert comprises: three or more corners along a perimeter; a main cutting edge formed on an edge between an upper surface and a main side surface, and a sub cutting edge formed on an edge between the upper surface and a sub side surface, wherein the main cutting edge and the sub cutting edge are placed in succession between the corners; and a flat lower surface. The main cutting edge forms an inclination angle such that a height decreases gradually in a direction toward the sub cutting edge. The main side surface is formed by a first end main side surface and a second end main side surface. The sub side surface is formed by a first end sub side surface and a second end sub side surface.

A cutting insert, used for a milling cutter, which includes two polygonal main surfaces that are opposite each other and a plurality of side faces and whose main surfaces are rake faces, whose side faces are flank faces, and whose ridge lines at positions where the main surfaces and the side faces cross each other are used as cutting edges include two major side surfaces that are opposite each other and a plurality of minor side surfaces that are formed continuously with the major side surfaces. A mounting hole is provided at the two major side surfaces in a direction in which the mounting hole extends therethrough, and areas of the two major side surfaces are greater than those of the main surfaces. The major side surfaces and the minor side surfaces are provided with flutes along entire regions of the cutting edges.

A cutting insert comprising a cutting edge formed by an intersection ridge between a rake face and a side face, the cutting edge including a major cutting edge, a flat cutting edge, and a chamfer edge disposed between the major cutting edge and the flat cutting edge, wherein in a direct view of a side face near the flat cutting edge, a ratio of installation area length L2 of the chamfer edge to installation area length L3 of the major cutting edge is L2:L3=2:8 to 5:5, and inclination angle .sub.1 of the chamfer edge with respect to the flat cutting edge and inclination angle .sub.2 of the major cutting edge with respect to the flat cutting edge are set to have a relationship of .sub.1<.sub.2.

In a cutting insert according to an embodiment of the present invention, an upper cutting edge includes, sequentially from a first corner to a second corner, a corner cutting edge, a minor cutting edge inclined as separating from the corner cutting edge at a first inclination angle on a basis of a vertical plane perpendicular to a central axis extending between upper and lower surfaces, and a major cutting edge inclined as separating from the minor cutting edge at a second inclination angle on the basis of the vertical plane so as to become more closer to the lower surface than the minor cutting edge. A cross section of a rake surface obtained by cutting an inwardly located end portion thereof along a direction of the central axis has a straight line shape or concave shape in a region crossing over at least a minor rake surface and a major rake surface. A cutting tool with the cutting insert, and a method of manufacturing a machined product by using the cutting tool are also provided.

An object is to provide a cutting insert for a milling cutter with which efficiency in machining can be increased. The cutting insert includes two polygonal main surfaces facing each other and side surfaces each connected to a corresponding side of each of the main surfaces. The side surfaces include a major side surface through which an attachment hole extends, a first minor side surface perpendicular to the major side surface, and a second minor side surface disposed between the first minor side surface and the major side surface. A ridge between each of the main surfaces and the major side surface forms a major cutting edge, and a ridge between each of the main surfaces and the second minor side surface forms a minor cutting edge. An angle between the major cutting edge and the minor cutting edge is 145 or larger.

A cutting insert, a cutting tool and method of manufacturing a machined product. The cutting insert includes: upper and lower surfaces; a side surface; a cutting edge; and a rake portion on the upper surface. The cutting edge includes major and minor cutting edges that are convex toward outside of the main body portion. The minor cutting edge has a curvature radius smaller than a curvature radius of the major cutting edge. The rake portion is inclined and approaches the lower surface as moving from the major cutting edge toward inside of the main body portion and is located along the major cutting edge. An inclination angle of the rake portion becomes smaller as moving from a part continuous with one end of the major cutting edge toward a part continuous with center of the major cutting edge.

Cutting insert with a cuboid body has a substantially square top face and bottom face, said top face and bottom face connected by four peripheral adjoining side surfaces. At least two cutting edges are formed at the transition of the top face to at least two side surfaces, that cutting edges defining a plane of the top face. To provide a cutting insert and a corresponding tool suited to produce valve seat surfaces with high precision but still having a rather simple construction and being precisely mountable with ease and less efforts of adjustment, the plane defined by the top face cutting edges of the cutting insert has maximum dimensions of 7 mm7 mm, where the bottom face has a supporting surface formed exactly parallel to the plane defined by the top face cutting edges by means of grinding within a tolerance of less than 5 angular minutes.