A cutting insert 2 includes an upper surface 6, a lower surface 7 on a side opposite to the upper surface 6, and a peripheral side surface 8 connecting the upper surface 6 and the lower surface 7. A cutting edge 61 is formed in at least a part of a first ridgeline 60 where the upper surface 6 and the peripheral side surface 8 intersect. At least one bottomed recess 10 recessed from the lower surface 7 to the upper surface 6 is formed in an outer peripheral portion of the lower surface 7. Each of the recesses 10 is formed in a substantially triangular shape having a first vertex P, a second vertex Q, and a third vertex R. The first vertex P and the second vertex Q are respectively positioned on a second ridgeline 70 where the lower surface 7 and the peripheral side surface 8 intersect. The third vertex R is positioned on the lower surface 7 and separated from the second ridgeline 70.

It is intended to allow a wide range including a low region (fine finishing) to a middle region (medium cutting) to be covered with a single insert. A cutting insert includes an upper surface, a lower surface, a peripheral side surface, a cutting edge including a main cutting edge and a corner cutting edge, a corner portion, a projecting portion formed to extend from the corner portion toward a central axis and including a first projection and a second projection, a rake portion, and an inclined portion provided at the cutting edge. The inclined portion has a first inclined portion beginning at an intermediate point in the corner cutting edge, while the rake portion has a shape in which an angular degree of a rake angle gradually increases with distance from the corner portion.

A cutting tool for turning includes a coupling portion, an intermediate portion and a cutting portion. The intermediate portion extends along a longitudinal center axis thereof between the coupling portion and the cutting portion. The cutting portion includes a first and a second nose portion. The first nose portion has a first cutting edge, a second cutting edge, and a convex nose cutting edge connecting the first and second cutting edges. The first and second cutting edges form a nose angle less than 90°. A longitudinal center axis of the coupling portion defines a tool rotational axis. The cutting portion includes a top surface, the top surface facing away from the coupling portion and the first and the second nose portions each form free ends of the cutting tool.

A cutting insert for a cutting tool includes a body having a cutting edge, a rake face, and micro channels provided on the rake face adjacent the cutting edge. The micro channels define a grid pattern of micro channels that intersect each other in a region of the rake face where contact between a chip and the rake face is assumed to occur during cutting with the cutting insert.

A cutting insert may include a first surface, a second surface and a third surface. The first surface may include a corner having a convex curvilinear shape and an inclined surface. The inclined surface may include a first inclined surface, a second inclined surface and a third inclined surface. The first inclined surface may be inclined at a first angle. The second inclined surface may be inclined at a second angle. The third inclined surface may be inclined at a third angle. The first inclined surface may have a concave curvilinear shape in a cross section orthogonal to a bisector of the corner. The second inclined surface may be a flat surface. The second angle may be smaller than either of the first angle and the third angle in a cross section which includes the bisector and is orthogonal to the reference plane.

A cemented carbide may include a hard phase including W and C, and a binder phase including cubic Co. The binder phase may include Zr. The Co may include a lattice constant of more than 3.5575 Å and not more than 3.5600 Å. A coated tool may include a coating layer located on a surface of the cemented carbide. A cutting tool may include a holder that is extended from a first end toward a second end and may include a pocket on a side of the first end, and the coated tool located in the pocket.

A cermet, as a base, containing a plurality of hard particles and a bonded phase between the plurality of hard particles. Each of the plurality of hard particles, when viewed in cross section, includes a first region containing Ti, N, and C, and contains a titanium carbonitride phase as a main constituent. Each of the plurality of hard particles, when viewed in cross-section, includes a second region containing one or more metal elements selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Co, and Ni in a larger amount than the first region. The content of the one or more metal elements in the second region is 9.5 mass % or more in a total amount. A cutting tool has a length extending from a first end to a second end, and includes a holder and the insert described above.

A holder according to one embodiment has a rod shape and includes a head portion located at a front end side. The head portion includes an upper jaw portion and a lower jaw portion located at a front end, an insert pocket located between the upper jaw portion and the lower jaw portion, a first wall surface located at an upper surface of the upper jaw portion and inclined in an extending manner from one side surface side, a second wall surface located closer to a rear end side than the first wall surface and inclined upward, a concave-shaped third wall surface located closer to the rear end side than the second wall surface, and a fourth wall surface inclined upward as the fourth wall surface extends away from the third wall surface. The third wall surface is concave downward from an upper end of the second wall surface.

Provided is a cutting insert easy to be gripped by an operator or a robot hand. First and second end surfaces (10, 20) are formed in substantially polygonal shapes having second and fourth corners (B, H) formed at obtuse angles and first and third corners (A, G) formed at acute angles. A peripheral side surface (30) includes a first curved portion (41) connecting the first and third corners (A, G), a second curved portion (42) connecting the second and fourth corners (B, H), and a first side surface (31) interposed between the first and second curved portions (41, 42). The first side surface (31) is inclined with respect to a center axis (O). The second curved portion (42) is provided with a grip portion (50), and the grip portion (50) includes at least one of a shape of each of plane surfaces (51, 53) chamfered parallel to the center axis (O) and a shape of a recessed portion (52) formed to be spaced apart from the first and second end surfaces (10, 20) and recessed toward the center axis (O).

An insert may include a main body. The main body may include a first surface, a second surface, a side surface, a first cutting edge and a through hole. The side surface may be located between the first surface and the second surface. The first cutting edge may be located on at least a part of a ridge line where a first side surface of the side surface intersects with a second side surface adjacent to the first side surface. The through hole may open into the first surface. The main body may further include a first concave part located from the first surface to the side surface. The first concave part may be located away from an imaginary straight line connecting the first cutting edge and a center of the through hole in a front view of the first surface.