A cutting insert includes an upper surface and upper edge. The upper surface includes a second side part, a first corner part, and a second corner part. The upper surface further includes a first surface and a second surface. The upper edge includes a first edge located at the first corner part, a second edge located at the second side part, and a third edge located at the second corner part. The second surface includes a first region extending toward the first corner part, and a second region extending toward the second corner part. A distance between the first region and the upper edge is smaller at a side of the second edge than at a side of the first edge. A distance between the second region and the upper edge is smaller at a side of the second edge than at a side of the third edge.

A cutting insert includes a main body including a first face, a second face, and a third face. The second face includes a rake face. Among the outer-peripheral sides of the second face, the boundary portion with the first face is a main cutting edge. When viewed from the side where the first face is disposed, the main cutting edge includes a first straight portion, a second straight portion, and a curved portion. The first straight portion is located adjacent to a reference side. The second straight portion is arranged at a distance from the first straight portion. The curved portion connects the first straight portion and the second straight portion. A first intersection angle of the first straight portion with respect to the reference side is different from a second intersection angle of the second straight portion with respect to the reference side.

A cutting insert has cutting edges having the same shape and provided at respective corners of a polygon in rotational symmetry about the center axis of the polygon, is clamped in an upright position to a holder, and has a negative side rake angle on a rake face of a side cutting edge. A side cutting edge is present at an intersection ridge between a polygonal face and an outer peripheral face. The outer peripheral face includes a rake face of the cutting edge and a flank of an end cutting edge of another cutting edge different from the side cutting edge. The flank has a positive slope angle in opposition to a negative side rake angle of the side cutting edge. A breaker groove extending in a front-rear direction is formed in the rake face and cuts into the flank, in such a manner as to divide the rake face.

A cutting insert has cutting edges having the same shape and provided at respective corners of a polygon in rotational symmetry about the center axis of the polygon, is clamped in an upright position to a holder, and has a negative side rake angle on a rake face of a side cutting edge. A side cutting edge is present at an intersection ridge between a polygonal face and an outer peripheral face. The outer peripheral face includes a rake face of the cutting edge and a flank of an end cutting edge of another cutting edge different from the side cutting edge. The flank has a positive slope angle in opposition to a negative side rake angle of the side cutting edge. A breaker groove extending in a front-rear direction is formed in the rake face and cuts into the flank, in such a manner as to divide the rake face.

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 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 includes a main body including a first face, a second face, and a third face. The second face includes a rake face. Among the outer-peripheral sides of the second face, the boundary portion with the first face is a main cutting edge. When viewed from the side where the first face is disposed, the main cutting edge includes a first straight portion, a second straight portion, and a curved portion. The first straight portion is located adjacent to a reference side. The second straight portion is arranged at a distance from the first straight portion. The curved portion connects the first straight portion and the second straight portion. A first intersection angle of the first straight portion with respect to the reference side is different from a second intersection angle of the second straight portion with respect to the reference side.

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 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 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.