A physical configuration of multiple-layer coatings formed with at least one layer of coating containing cubic born nitride (cBN) particles with one or more layers in composite form containing cBN particles may have a thickness of each individual layer as thin as in the nanometer range, or as thick as in the range of a few microns and even up to tens of microns. The chemistry of the composite layer consists of any individual phase of (a) nitrides such as titanium nitride (TiN), titanium carbonitride (TiCN), and hafnium nitride (HfN); (b) carbides such as titanium carbide (TiC); and (c) oxides such as aluminum oxide (AI.sub.2O.sub.3) or any combination of the above phases, in addition to cBN particles. The coating or film can be stand-alone or on a substrate.

A rotary cutting tool insert according to one embodiment of the present invention includes: an annular rake face provided with at least one recess portion; and a cutting edge formed at an outer circumference of the rake face, the recess portion having a width of more than or equal to 1.2 mm and less than or equal to 3.0 mm in a circumferential direction of the rake face, a distance between the cutting edge and an end of the recess portion at the outer circumference side of the rake face being more than or equal to 0.1 mm and less than or equal to 0.5 mm. According to the rotary cutting tool insert according to the one embodiment of the present invention, roughness of a processed surface and vibration due to a cutting process can be prevented.

A turning insert has two opposite main surfaces and a peripheral surface which extends therebetween and has N side surfaces, where 2<N<9. The insert has mirror symmetry about a mid-plane and 360/N degree rotational symmetry about a central axis perpendicular to the mid-plane. The insert has two main edges which each have N main cutting edges and N corner cutting edges. Each main cutting edge has two raised edge portions and a lowered edge portion. Each main surface has N main rake surfaces and N corner rake surfaces. Each main surface further has at least N convex island protrusions and N at least partially convex peninsula protrusions, any and all island protrusions associated with a given main rake surface being located between two adjacent peninsula protrusions, each pair of adjacent peninsula protrusions having at least one island protrusion located therebetween.

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.

A turning insert arranged for longitudinal turning of metal work pieces includes a nose cutting edge that slopes from a trailing cutting edge in direction towards a leading cutting edge. A turning tool is also disclosed.

A cutting insert for profile turning, in particular for wheel profile turning, includes an upper surface, a lower surface, and side surfaces. At the transition from the upper surface to the side surfaces two cutting edges are formed for machining a workpiece and two further edges each having two ends. The two cutting edges are designed part-circular in shape and each extend from one end of one of the two edges to the opposite end of the other of the two edges. Also described is a cartridge for holding a cutting insert, the cartridge being mountable on a machine tool. The cartridge has a main seating surface having a plane angle () of greater than 90 to the axis of rotation (D) of the workpiece.

To provide a cutting insert that readily fragmentizes chips, and that has excellent durability.

At least a cutting part of a cutting insert is formed of a sintered compact. The sintered compact includes a chip breaker that is a recessed portion in which a partial region of a cutting part upper surface is depressed downward. The chip breaker includes a downward inclined surface, an upward inclined surface, a jutting portion that juts out along a first axial line that passes through a distant end of a cutting edge, and a stepped surface that adjoins the jutting portion in a Y axis direction orthogonal to the first axial line. An upper end of the jutting portion is formed at a height of an upper stage. The stepped surface is formed at a height of an intermediate stage at a part closest to the first axial line.

There is provided a cutting insert having a low possibility that chips roughen a machined surface of a workpiece in back turning. The cutting insert includes a rake surface, a peripheral side surface, a front cutting edge which is provided on a ridge of the rake surface and the peripheral side surface, and a main cutting edge which is provided on the ridge so as to be continuous with the front cutting edge and has an extension direction which forms an obtuse angle with an extension direction of the front cutting edge, the main cutting edge is curved into a U shape over an entire length of an effective edge range which functions as a cutting blade, and the deepest point of the U shape is positioned in a range closer to a side of a corner than a position which divides a straight line connecting both ends of the main cutting edge at a ratio of 2:1 from the side of the corner positioned adjacent to the front cutting edge.

A cutting insert may include a first surface and a second surface. The first surface may include a first side, a first corner, a second corner, and a breaker part. The breaker part may include a first segment, a second segment, and a third segment. The first segment may be an inclined surface inclined so as to approach the second surface as going away from the first side. The third segment may be an inclined surface inclined so as to separate from the second surface as going away from the second segment. In a front view of the first surface, a maximum value at a side of the second corner may be greater than a maximum value at a side of the first corner in a distance from the first side to a top portion of the third segment on an orthogonal line with respect to the first side.