Abstract: A turning insert includes corner surfaces each defined by at least five circle segments arranged in succession between adjacent side surfaces. Successive ones of the circle segments have different radii of curvature. The segments include a center or first segment intersected by a bisector of the corner surfaces, second and third segments disposed on respective sides of the first segment, and third and fourth segments disposed adjacent respective sides of said second and third segments, respectively. The first segment defines a first radius. The second and third segments defining equal second and third radii. The fourth and fifth segments defining equal fourth and fifth angles. Each of the fourth and fifth angles is larger than the first radius. The first radius is larger than each of the second and third angles.

Abstract: The present invention provides an indexable insert for grooving operations, the basic form of which is triangular, the insert comprises extensions in each cutting corner. Each extension has a cutting edge which intersects with two converging edges. The extensions may have a symmetrical or non-symmetrical configuration. The top surface of the extension provides a rake face in regard to the cutting edge and a clearance face of the cutting edge is oriented in the direction of the thickness of the insert.

Abstract: A cutting insert for chip forming machining of workpieces is disclosed. The insert includes at least one end-positioned cutting head having an upper surface with a cutting edge extending across the width of the cutting insert and the ends of the cutting edge adjoining front chip surface side portions. A chip-deforming depression is provided between the front chip surface side portions. The rake angle of the chip surface side portions is consistently negative while the rake angle of a surface of the depression adjacent the cutting edge is consistently positive.