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 insert has a cutting corner, having a bisector, located on a top surface of the cutting insert. A chip-control arrangement is located at the cutting corner. The chip-control arrangement includes a projection protruding from the top end face and that extends longitudinally in a direction transverse to, and to opposites sides of, the bisector. The chip-control arrangement also includes a protrusion protruding from the top end face and comprising a protrusion ridge that extends from the projection towards a corner cutting edge at the cutting corner.

The cutting insert is provided with: a top surface, a bottom surface, a side surface, a cutting edge located at the intersection portion of the top surface and the side surface; a through hole located from the top surface to the bottom surface; a projecting portion extending from a corner section to a through hole side; and a rake surface located between the cutting edge and the projecting portion. A boundary line between the rake surface and the projecting portion comprises a first end. In a top view, a bisector of the corner section intersects the cutting edge at a first point and intersects a top edge section of the through-hole at a second point. The first end is located closer to the through-hole side than a perpendicular line that passes through a midpoint of a line segment connecting the first point and the second point.

A cutting insert includes a rake face, a flank face, a cutting edge formed at a ridge where the rake face and the flank face intersect, a land provided on the rake face along the cutting edge, a breaker groove provided in the rake face inside of the land, and a curved surface formed between a groove surface of the breaker groove and the land. A radius of curvature of the curved surface is 0.5 mm or greater.

A cutting insert according to an embodiment of the present invention has a body section and a cutting section located closer to a front end side than the body section. The cutting section has an end cutting edge located along an intersection of an upper surface and a side surface, a recess located from the end cutting edge toward the body section, and a pair of protrusions opposed to each other with the recess interposed therebetween. The pair of protrusions has a first protrusion and a second protrusion located on the first protrusion. The first protrusion has a first inclined surface that is inclined upward and approaches another one of the pair of protrusions as going from the front end side toward the rear end side. A periphery of the second protrusion which is close to the front end side has a convex curvilinear shape in a top view.

A method to form a surface on a metal work piece includes providing a turning insert that has a nose angle formed between first and second cutting edges less than or equal to 85; providing a turning tool having a tool body with an insert seat in which the turning insert is mountable; arranging the orientation of the second cutting edge such that it forms a back clearance angle of more than 90 in a feed direction; rotating the metal work piece around a rotational axis in a first direction; moving the turning insert in a direction parallel to or at an angle less than 45 relative to the rotational axis; and setting the longitudinal axis of the tool body at an angle greater than zero but less than or equal to 90 relative to the rotational axis of the metal work piece.

A cutting insert according to one embodiment of the present invention comprises an upper surface, a lower surface, a lateral surface, a cutting edge, and a fastening hole, wherein the cutting edge includes a main cutting edge, a nose R part connected to the main cutting edge, and a sub-cutting edge connected to the nose R part, the upper surface includes a land part adjacent to the cutting edge, an inclined surface downwardly inclined from the land part, and an upper surface bottom part extending from the inclined surface, first and second protrusion parts are formed respectively, in which the first protrusion part is connected to a main cutting edge land part and formed on a main cutting edge inclined surface at a portion at which a nose R part inclined surface ends and the second protrusion part is connected to a sub-cutting edge land part and formed on a sub-cutting edge inclined surface at a portion at which the nose R part inclined surface ends, and no protrusion is present on the nose R part inclined surface.

A cutting insert includes an insert body, a rake face on an upper surface of an end portion of the insert body, a cutting edge on a ridge between the rake face and an end surface of the insert body, side cutting edges on ridges between the rake face and side surfaces of the insert body, each connected to both end portions of the cutting edge, and a breaker convex portion on the rake face. The breaker convex portion includes two breaker island portions extending toward the side cutting edge as extending closer to the front cutting edge. Each breaker island portion includes from the front cutting edge side a first raised portion, a descending portion which becomes lower from a top portion of the first raised portion, and a second raised portion which becomes higher, from the descending portion, than the top portion of the first raised portion.

A turning tool holder includes a tool body, a cutting tool insert, and a shim. A coolant conduit system extends through the turning tool holder, a first portion of the coolant conduit system extending through the tool body and an end portion of the coolant conduit system extending through the shim. The end portion of the coolant conduit system includes a through hole extending from a first surface to an opposite second surface of the shim. The end portion has a coolant outlet opening at the second surface, the coolant outlet opening being formed by the shim alone. A jet of coolant from the coolant outlet opening may be directed towards a space expected to have a cutting zone of a workpiece. Further a cutting tool insert arranged to be used in a turning tool holder is disclosed.

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.