An indexable cutting insert comprises a flank face having a generally parallelogram shape and a plurality of side faces. The flank face is bounded by a plurality of edges. Each edge joins the flank face with one of the side faces. The plurality of edges comprises a first cutting edge and a second cutting edge. The first cutting edge has a shape corresponding to a portion of a first bent curve and the second cutting edge has a shape corresponding to a portion of a second bent curve. The second bent curve is obtainable by a translation of the first bent curve along a width direction of the cutting insert. The cutting insert has a two-fold rotational symmetry with respect to an axis of symmetry that is perpendicular to the width direction, a longitudinal direction of the cutting insert being perpendicular to the width direction and the axis of symmetry.

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.

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.

An indexable cutting tool of a lever-lock type applies a clamping force. At a bottom of an insert fixing portion, there is formed a pillar-shaped lever in a state in which one end protrudes from a placement surface of the insert fixing portion. A screw applies a pressing force to the lever between the one end and a portion such that the lever is pressed and inclined with the portion s a fulcrum in the middle of the lever so that the one end applies a clamping force to the cutting insert.

A cutting tool has an insert holder and a cutting insert releasably attached thereto. The cutting insert has an insert edge which includes two nose cutting edges and a convex corner cutting edge which extends therebetween. The two nose cutting edges form a nose angle. The insert edge also includes two mid-side edges which are located further from the corner cutting edge than the nose cutting edges. The two mid-side edges form a mid-side angle. The nose angle is less than the mid-side angle.

Disclosed is a cutting insert having a generally polygonal primary body having a primary body base connected to an opposing and similarly-shaped body face through a plurality of primary flank portions extending there between. The cutting insert further includes at least one cutting protrusion extending away from at least one of the primary flank portions, and merging therewith. The cutting protrusion includes a rake face coplanar and extending away from the adjacent primary flank portions, and an edge portion extended towards a cutting flank portion. The cutting protrusion further includes a tip flat extending between a rake front from a protrusion tip towards a rake root portion, adjacent one of the primary flank portions.

A cutting tool for thread cutting has a thread turning cutting insert releasably retained in an insert pocket by a fastening member. The thread turning cutting insert has a thread cutting portion having three spaced apart cutting teeth. and a chip forming groove recessed in an insert upper surface. The chip forming groove includes a near-flank groove surface close to the cutting teeth and far-flank grove surface further away from the cutting teeth. The thread cutting portion includes three cutting edges formed at the intersection of the insert upper surface and an insert peripheral surface. Each cutting edge is located on a respective cutting tooth. The thread cutting portion includes three planar land surfaces located on the insert upper surface. Each land surface extends from an entire length of a respective cutting edge to the near-flank groove surface.