Abstract: A cutting insert has a plate shape centered on an insert center axis. The cutting insert includes a front surface and a back surface facing an insert axial direction, an outer peripheral surface facing outward in an insert radial direction, and a cutting edge at an intersecting ridge line between the front surface and the outer peripheral surface. The back surface has a flat shape perpendicular to the insert center axis. The outer peripheral surface includes a flank surface coupled. The flank surface is inclined inward in the insert radial direction as extending in the insert axial direction from the front surface side to the back surface side. The front surface includes a rake surface. The rake surface is inclined from a back surface side to a front surface side in the insert axial direction as extending inward in the insert radial direction from the cutting edge.

Abstract: A cutting insert has an insert major body which includes two hexagonal faces facing each other and six side faces arranged around the two hexagonal faces, and is rotationally symmetrical at 120° intervals about an insert center line passing through centers of the two hexagonal faces and inversely symmetrical in front and back with respect to the two hexagonal faces, wherein a major cutting edge and an minor cutting edge are alternately formed in a circumferential direction in the single hexagonal face at twelve intersecting ridgeline portions at which the hexagonal faces and the side faces intersect, the major cutting edge is formed to be located at an intersecting ridgeline portion with one hexagonal face while the minor cutting edge is formed to be located at an intersecting ridgeline portion with the other hexagonal face at a single side face.

Abstract: A cutting insert has a plate shape centered on an insert center axis. The cutting insert includes a front surface and a back surface facing an insert axial direction, an outer peripheral surface facing outward in an insert radial direction, and a cutting edge at an intersecting ridge line between the front surface and the outer peripheral surface. The back surface has a flat shape perpendicular to the insert center axis. The outer peripheral surface includes a flank surface coupled. The flank surface is inclined inward in the insert radial direction as extending in the insert axial direction from the front surface side to the back surface side. The front surface includes a rake surface. The rake surface is inclined from a back surface side to a front surface side in the insert axial direction as extending inward in the insert radial direction from the cutting edge.

Abstract: A minor cutting edge has a first minor cutting edge and a second minor cutting edge that extends inward of the insert in a direction of an insert short side face axial line, as the second minor cutting edge extends from the first minor cutting edge in a direction of an insert major face axial line. A flank face of the second minor cutting edge is inclined outward of the insert in the direction of the insert short side face axial line, as the flank face extends from the second minor cutting edge in the direction of an insert long side face axial line, and is inclined outward of the insert in the direction of the insert short side face axial line, as the flank face extends from a major face adjacent to the flank face in the direction of the insert major face axial line.

Abstract: A cutting insert has an insert major body which includes two hexagonal faces facing each other and six side faces arranged around the two hexagonal faces, and is rotationally symmetrical at 120° intervals about an insert center line passing through centers of the two hexagonal faces and inversely symmetrical in front and back with respect to the two hexagonal faces, wherein a major cutting edge and an minor cutting edge are alternately formed in a circumferential direction in the single hexagonal face at twelve intersecting ridgeline portions at which the hexagonal faces and the side faces intersect, the major cutting edge is formed to be located at an intersecting ridgeline portion with one hexagonal face while the minor cutting edge is formed to be located at an intersecting ridgeline portion with the other hexagonal face at a single side face.

Abstract: A minor cutting edge has a first minor cutting edge and a second minor cutting edge that extends inward of the insert in a direction of an insert short side face axial line, as the second minor cutting edge extends from the first minor cutting edge in a direction of an insert major face axial line. A flank face of the second minor cutting edge is inclined outward of the insert in the direction of the insert short side face axial line, as the flank face extends from the second minor cutting edge in the direction of an insert long side face axial line, and is inclined outward of the insert in the direction of the insert short side face axial line, as the flank face extends from a major face adjacent to the flank face in the direction of the insert major face axial line.