A cutting insert for groove machining is provided, which includes a front cutting edge, a chip breaker groove extending from a rear direction of the front cutting edge in a lengthwise direction of the cutting insert, land portions formed on both sides of the chip breaker groove, and inclined surfaces in continuity with the land portions and extending from the land portions to a rear direction of the cutting insert, in which a distance in a transverse direction between left and right walls of the chip breaker groove gradually increases from an entrance of the chip breaker groove toward a boundary between the land portions and the inclined surfaces, and then gradually decreases upon passing the boundary, and the cutting insert is symmetrical about a longitudinal center line thereof.

A parting/grooving insert and a method of grinding a parting/grooving insert including rotating a plane grinding surface having a normal vector parallel to the axis of rotation and a tangential direction of rotation; providing a parting/grooving insert including a rake surface, a main clearance surface, and a main cutting edge formed between the rake and main clearance surfaces; orienting/positioning the insert relative to the grinding surface, such that the main clearance surface is parallel to the grinding surface, the normal vector of the main cutting edge being in the plane of the main clearance surface and with a vector component in the direction of rotation forming an angle to the tangential direction of rotation at the insert of at least 20 degrees from parallel orientation; and grinding the main clearance surface to provide grinding marks having an angle to the normal vector of the main cutting edge corresponding to the angle to the tangential direction of rotation.

Provided is a cutting tool for back turning capable of improving chipping resistance. A cutting tool wherein a wall surface of a chip breaker includes a first wall surface that is formed along a first ridgeline, and a reinforcing surface that is connected to the first wall surface and a first end surface at an end portion of the chip breaker on the side of a first cutting edge, and that forms an angle of 90 degrees or an obtuse angle with the first end surface.

A parting-off insert for relatively high feed includes a rake surface including a reinforced front sub-edge extending between two convex corner sub-edges. A cutting width W.sub.C is defined between distal points of the first and second convex corner sub-edges. The cutting width W.sub.C fulfills the condition: W.sub.C6 mm. The front sub-edge including a minimum front sub-edge thickness T.sub.F fulfilling the condition: T.sub.F>0.20 mm.

The edge portion includes an upper surface, a side surface, and a land surface. The side surface has a front side surface and a pair of lateral side surfaces. An intersection between the land surface and the front side surface forms a front cutting edge. An intersection between the land surface and each of the pair of lateral side surfaces form a corresponding one of a pair of lateral cutting edges. The edge portion contains 80 vol % or more of diamond. A chip breaker recess is provided between the upper surface and the land surface. The surfaces forming the chip breaker recess include a rake face and a breaker wall surface. The upper surface has a front edge portion opposite to the front cutting edge from the chip breaker recess. A pair of protruding portions are provided to extend from the front edge portion toward the front cutting edge.

A turning insert includes a head portion connected to a stem portion. A CBN cutting edge includes a surface generating cutting edge and two major cutting edge portions, such that each major cutting edge portion forms an angle of 5-20 in relation to a tangent line of the cutting edge at a forward point of the cutting edge.

The present invention provides a cutting insert that exhibits superior chip control during both grooving and cross feeding. The cutting insert includes an upper face, a front face that forms an intersecting ridgeline with the upper face, side faces that are connected to the front face and form intersecting ridgelines with the upper face, a front face cutting edge provided on the intersecting ridgeline between the upper face and the front face, and side cutting edges provided on the intersecting ridgelines between the upper face and the side faces. The upper face includes a first upper face portion and an undulating upper face portion on which peaks and troughs are formed continuously in a direction heading away from the front face cutting edge, the undulating upper face portion being provided on both lateral direction sides of the first upper face portion. The undulating upper face portion is configured such that the side cutting edges, when seen from the side, each have a continuous undulating shape from the front face cutting edge.

A cutting insert in the present disclosure includes an upper surface, a lower surface, a side surface, and an edge. The upper surface includes a first corner part and a second corner part. The edge is located in a region which is located between the first corner part and the second corner part. The edge includes a first edge located at a side of the first corner part, a second edge located at a side of the second corner part, and a third edge located between the first edge and the second edge. The edge has a curvilinear shape being recessed toward the lower surface in a side view. Each of a radius of curvature R1 of the first edge and a radius of curvature R2 of the second edge is smaller than a radius of curvature R3 of the third edge in a side view.

A cutting insert according to an aspect includes a base portion and a cutting portion. The cutting portion includes an upper surface, a side surface, a ridge line including a first ridge line and a second ridge line, and an intersection point. The upper surface includes a top surface region and a rising surface region located between the top surface and the ridge line, and having a shape protruding toward the intersection point. In a top view, a first distance from the first ridge line to the rising surface increases as close to the intersection point, and a second distance from the second ridge line to the rising surface increases as close to the intersection point.

Provided is a cutting insert that improves chip control performance. In a cutting insert for back turning process, a chip breaker wall face, of a chip breaker, facing the axial feed direction includes: when viewed from a first face side, a first wall face portion configured so that a ridgeline connecting a top portion of the chip breaker and the first wall face portion is a straight line; and a second wall face portion connected to the first wall face portion on a first cutting edge side and configured so that a ridgeline connecting the top portion of the chip breaker and the second wall face portion is closer to a second cutting edge side than the straight line.