A cutting insert according to one embodiment includes: a rake face; a flank face continuous to the rake face; and a cutting edge constituted of a ridgeline between the rake face and the flank face. A coolant flow path is provided inside the cutting insert. One end portion of the coolant flow path opens in the flank face to form a coolant ejection hole. The flank face is provided with a coolant guide groove extending from the coolant ejection hole toward the cutting edge with a base end portion of the coolant guide groove being connected to the coolant ejection hole and with a front end portion of the coolant guide groove being disposed at a position close to the cutting edge relative to the base end portion.

A coolant supply mechanism is attachable to a cutting insert. The cutting insert has a first bottom surface, a first upper surface, and a first side surface. The first upper surface includes a corner portion that is located at a corner of the first upper surface when viewed in a plan view and that is contiguous to the first side surface so as to form a cutting edge, and a center portion located adjacent to the corner portion on a side opposite to the cutting edge when viewed in a plan view. The first upper surface is depressed toward the first bottom surface side at the center portion.

A cutting insert capable of performing front-turning and high feed back-turning according to one embodiment includes: an upper surface; a lower surface opposite to the upper surface in a vertical direction; a side portion configured to connect the upper surface and the lower surface; a mounting hole extending through the upper surface and the lower surface; and a plurality of cutting edges formed at edges where the upper surface meets the side portion, wherein the upper surface has one or more cutting corners, the plurality of cutting edges include a major cutting edge and a minor cutting edge extending from the cutting corner, and a representative inclination of the minor cutting edge used for high feed back-turning is greater than a representative inclination of the major cutting edge used for front-turning with respect to a virtual reference plane perpendicular to the vertical direction.

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 insert may include a first surface including a corner and a first side, a second surface, a third surface, an inclined surface located between the first surface and the third surface, a first ridgeline located on an intersection of the inclined surface and the first surface, and a second ridgeline located on an intersection of the inclined surface and the third surface. An imaginary straight line passing through a center of the first surface and a center of the second surface may be a central axis. In a cross section which is parallel to the central axis and is orthogonal to the first side, an imaginary straight line connecting the first ridgeline and the second ridge line may be a first straight line, and the inclined surface may include a first inclined surface located more away from the central axis than the first straight line.

A cutting insert capable of performing front-turning and high feed back-turning according to one embodiment includes: an upper surface; a lower surface opposite to the upper surface in a vertical direction; a side portion configured to connect the upper surface and the lower surface; a mounting hole extending through the upper surface and the lower surface; and a plurality of cutting edges formed at edges where the upper surface meets the side portion, wherein the upper surface has one or more cutting corners, the plurality of cutting edges include a major cutting edge and a minor cutting edge extending from the cutting corner, and a representative inclination of the minor cutting edge used for high feed back-turning is greater than a representative inclination of the major cutting edge used for front-turning with respect to a virtual reference plane perpendicular to the vertical direction.

A cutting insert in a non-limiting aspect of the present disclosure may include an upper surface, a lower surface, a lateral surface and a cutting edge. The upper surface may include a first corner and a first side. The upper surface may further include a first protrusion and a second protrusion. The first protrusion may be extended toward the first corner. The second protrusion may be located between the first corner and the first protrusion. The first protrusion may include an inclined surface. The inclined surface may be located along the first side. The inclined surface may include a first surface and a second surface. The second surface may be located further away from the first corner than the first surface. The first surface and the second surface may be individually inclined upward as going away from the first side, and having a concave shape as a whole.

A cutting insert has a top surface, a seating surface, and an outer peripheral surface. The cutting edge includes a corner cutting edge portion, a first cutting edge portion, and a second cutting edge portion. The top surface includes a first rake face, a second rake face, a third rake face, a front side surface, an upper surface, a first side surface, and a second side surface. A ridgeline between the first side surface and the second side surface is continuous to the upper surface. When seen in a direction perpendicular to the seating surface, a width of a boundary between the front side surface and the third rake face is larger than a width of a boundary between the front side surface and the upper surface.

A cutting insert has a top surface, a seating surface, and an outer peripheral surface. The cutting edge includes a corner cutting edge portion, a first cutting edge portion, and a second cutting edge portion. The top surface includes a first rake face, a second rake face, a third rake face, a front side surface, an upper surface, a first side surface, and a second side surface. A ridgeline between the first side surface and the second side surface is continuous to the upper surface. When seen in a direction perpendicular to the seating surface, a width of a boundary between the front side surface and the third rake face is larger than a width of a boundary between the front side surface and the upper surface.

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.