A cutting insert includes a rake face, a seating face facing an opposite side to the rake face and seated on an insert mounting seat, and a flank face extending around the rake face and the seating face, in which two cutting edges each having an arcuate cutting edge portion extending in an arc shape and a linear cutting edge portion which is in contact with the arcuate cutting edge portion are formed on an intersecting ridgeline portion between the rake face and the flank face, a groove portion having a wall surface coming into contact with a projection portion protruding from a bottom surface of the insert mounting seat is formed on the seating face, and the groove portion has a narrow width portion in which a groove width decreases from one end side toward the other end side in a direction in which the groove portion extends.

An insert is provided, ensuring to vary the cutout angle of the cutting edge without replacing the body, and to prevent the change in the cutout angle of the cutting edge in the cutting process. The insert includes a constraining part, a through hole, and a blade. The blade includes a cutting edge for the cutting process. An outer surface of the constraining part around the central axis includes a pair of first constraining surfaces, and a pair of second constraining surfaces. The cutting edge in the state where the pair of first constraining surfaces are fixed becomes non-parallel to the cutting edge in the state where the constraining part is rotated around the central axis from the fixed state of the pair of first constraining surfaces to place the pair of second constraining surfaces on the same surface on which the pair of first constraining surfaces have been fixed.

A cutting insert includes a rake face configuring one of polygonal surfaces, a seating surface configuring the other one of the polygonal surfaces, and a side surface connecting the rake face and the seating surface to each other. The cutting insert has a cutting edge portion including a main cutting edge located in a side portion of the rake face, a subsidiary cutting edge connected to the main cutting edge, and a corner cutting edge connected to the subsidiary cutting edge and located in a corner portion of the rake face. The side surface includes a flank face and a connection surface which are adjacent to each other in a thickness direction via a boundary line. The connection surface is located on the seating surface side, and is located outside than an extension line of the flank face.

A cutting edge has a corner cutting edge, a flat drag, and a main cutting edge. The rake surface has a first rake surface portion, a second rake surface portion, and a third rake surface portion. The first rake surface portion has a first inclined surface inclined at a first angle. The second rake surface portion has a second inclined surface inclined at a second angle greater than the first angle. The first end portion and the second end portion are higher than the reference surface in a direction perpendicular to the reference surface, and the main cutting edge extends so as to intersect the reference surface when viewed in a direction parallel to the reference surface. A first step portion rising from the third rake surface portion and continuous with the first rake surface portion is provided on the rake surface.

An object of this disclosure is to provide a cutting insert that is shaped so that a major cutting edge is not damaged easily. In the cutting insert, a major cutting edge, a corner edge, a flat cutting edge and an inner cutting edge are formed on at least an upper surface, a protruding portion protruding outward is formed in a major cutting edge side surface portion of a side surface that corresponds to the major cutting edge, and a first section is formed in which, when viewed from above, the protrusion amount becomes smaller as the protruding portion separates from the corner edge. Furthermore, the cutting insert includes a first clearance angle changing portion in which a clearance angle becomes smaller as a major cutting edge flank portion formed in a major cutting edge side surface portion separates from the corner edge, and a second clearance angle changing portion in which the clearance angle becomes larger as the major cutting edge flank portion separates from the corner edge, wherein the first clearance angle changing portion is preferably positioned closer to the corner edge than the second clearance angle changing portion is, and, of end portions of the first clearance angle changing portion, the value of the clearance angle at a distal end portion from the corner edge is preferably negative.

A cutting insert includes a body portion having an upper surface, a lower surface located opposite the upper surface, and side surfaces extending between the upper surface and the lower surface. The body portion disposed about an axis passing through the upper and lower surfaces. The cutting insert further including a plurality of projecting portions provided integrally with the body portion at an outer position thereof in a direction orthogonal to the axis. Each projecting portion has an upper and lower surface, two side surfaces, a side end surface extending between the side surfaces, a round corner surface extending between the upper and side end surfaces, and a cutting edge formed between at least one of the side surfaces and the side end surface. The side surface of each projecting portion is structured to engage a first or second contact surface of a mounting seat formed in a cutter body.

A cutting blade having a plurality of different coatings on surfaces thereof, including an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface, wherein the upper surface intersects the side surface to form at least one cutting edge unit, the cutting edge unit includes a main cutting edge and a secondary cutting edge, the upper surface includes at least one set of cutting planes, the cutting planes include a main cutting surface and a secondary cutting surface, the main cutting surface intersects the side surface to form the main cutting edge, the secondary cutting surface intersects the side surface to form the secondary cutting edge, a main coating is provided on the main cutting surface, a secondary coating is provided on the secondary cutting surface, and the main coating and the secondary coating are independent from each other.

A cutting insert has a cutting edge formed on part of an intersecting ridge line portion of an upper face or a lower face and a side face. The cutting edge includes a major cutting edge, a minor cutting edge, and a connecting cutting edge that connects the major cutting edge and the minor cutting edge. A minor cutting edge flank that is part of the side face and that corresponds to the minor cutting edge includes a first minor cutting edge flank that connects to the minor cutting edge and that has a clearance angle of 0, and a second minor cutting edge flank that connects to the first minor cutting edge flank and that has a clearance angle of a negative value. A connecting cutting edge flank that is part of the side face and that corresponds to the connecting cutting edge includes a first connecting cutting edge flank that connects to the connecting cutting edge and that has a clearance angle of 0 or greater, and a second connecting cutting edge flank that connects to the first connecting cutting edge flank and has a clearance angle that is greater than the clearance angle of the first connecting cutting edge flank.

A cutting insert includes a top face and a bottom face parallel to the top face. Four side faces and four corner faces extend between the top and bottom faces. At least one cutting edge is formed at an intersection of the top face and at least one of the corner faces and two of the side faces connected to the corner face. The top face forms a rake surface, while an upper part of the corner face and the two side faces form a relief surface connected to the cutting edge. In order to reduce the cycle time for crank shaft milling, the cutting insert has two diagonally opposed corners including an acute angle between 70 and 85. At least one of the acute angled corners including the corner face providing a corner cutting edge. A disc milling tool including such cutting inserts is also provided.

A single-sided four-way indexable cutting insert includes a positive basic shape, a rake surface, a peripheral surface including four side abutment surfaces, a base bearing surface and a screw hole connecting the rake and base bearing surfaces. The insert has an imaginary square frustum which defines a square base containing the cutting insert's base bearing surface, and further defines four isosceles trapezoid side surfaces respectively containing the cutting insert's four side abutment surfaces. A material volume V.sub.F of the cutting insert and a void volume V.sub.S of the insert fulfill the condition V.sub.S/V.sub.F0.25.