A cutting insert for a milling tool is provided. A median plane extends through the cutting insert. A longitudinal plane extends perpendicularly to the median plane. In a view towards a first side surface, a first axial relief face and a first axial abutment face form part of a first surface grouping on a first side of the longitudinal plane. In a view towards a second side surface, a second axial relief face and a second axial abutment face form part of a second surface grouping on the first side of the longitudinal plane. The first axial abutment face forms a substantially flat surface. The first axial abutment face extends perpendicularly to the median plane. The second axial abutment face forms a substantially flat surface. The second axial abutment face extends perpendicularly to the median plane.

A cutting insert may include a first surface, a second surface and a lateral surface. The first surface may have a polygonal shape and may include a first corner, a second corner, a third corner, a first side and a second side. The lateral surface may include a first lateral surface and a second lateral surface. At least a part of the first lateral surface may be located between the first side and the second surface. At least a part of the second lateral surface may be located between the second side and the second surface. The first lateral surface may be located further outside than the first side in a front view of the first surface. The first lateral surface may include a first region located closer to the second lateral surface as coming closer to the second surface.

A cutting insert for a rotary cutting tool has a second surface that includes a second seating surface having a shape of a flat surface. The first cutting edge has a first main cutting edge portion and a first sub cutting edge portion. The second cutting edge has a second main cutting edge portion and a second sub cutting edge portion. When viewed in a direction from the first surface toward the second surface, at least a portion of the second sub cutting edge portion is located outside the first main cutting edge portion, and at least a portion of the first sub cutting edge portion is located outside the second main cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first sub cutting edge portion and the second sub cutting edge portion has a shape of a curved line.

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.

Chip discharge control is further improved. A cutting insert includes an upper surface, a lower surface, a screw hole having an axis penetrating from the upper surface to the lower surface, a peripheral side surface, and a major cutting edge, a wiper edge, and an inner edge formed in an intersecting region between the upper surface and the peripheral side surface. In a side view in which the peripheral side surface on which the inner edge is formed is seen from a direction perpendicular to the axis, the inner edge includes a recessed part recessed toward the lower surface, a length D.sub.L of the inner edge on one side of the recessed part in the side view is longer than a length D.sub.R of the inner edge on the other side of the recessed part, a lowest point of the inner edge is at a position lower than a flat part of the upper surface, and at least a part of the inner edge on the one side is at a position higher than the flat part of the upper surface. A cutting edge angle φ.sub.23L of the inner edge on the one side of the recessed part is larger than a half of a cutting edge angle φ.sub.23R of the inner edge on the other side of the recessed part.

A cutting insert has an upper surface, a lower surface and a lateral surface. The upper surface has a first upper side, and a second upper side. The lower surface has a first lower side and a second lower side. The lateral surface has a first lateral surface, a second lateral surface, and a third lateral surface. The first lateral surface has a first concave part having a first constraining surface having a flat shape. The second lateral surface has a second concave part having a second constraining surface having a flat shape. The third lateral surface has a convex part. The first concave part and the second concave part are separated from each other by the convex part.

To provide a cutting insert that is properly manufactured with ease of use. A cutting insert has a first end face, a second end face on the opposite side from the first end face, and a peripheral side surface that is parallel to a central axis connecting the center of the first end face and the center of the second end face and connects the first end face and the second end face. A first major cutting edge is formed on the outer edge of the first end face. A first flank facing the first major cutting edge is formed between the first major cutting edge and the peripheral side surface and has a negative clearance angle α with respect to the peripheral side surface. The peripheral side surface includes a first side surface facing the first flank. Between the first flank and the first side surface, a recess line is formed to extend along a virtual edge line where a virtual plane extending from the first flank and a virtual plane extending from the first side surface cross each other, and the recess line is formed with a notch on the virtual edge line.

A double-sided cutting insert for milling includes first and second major faces, a peripheral surface arranged between the major faces and including a first main side face, a first main cutting edge formed at an intersection between the first main side face and the first major face, a second main cutting edge formed at an intersection between the first main side face and the second major face, first and second inclined side surfaces, which are formed on the first main side face and which are inclined towards each other to form a depression on the first main side face, and a chip deflecting member formed on the first main side face as a protrusion across the depression and which includes a chip deflecting surface configured to deflect chips, which hit the first main side face, away from the depression.

To provide a cutting insert that is properly manufactured with ease of use. A cutting insert has a first end face, a second end face on the opposite side from the first end face, and a peripheral side surface that is parallel to a central axis connecting the center of the first end face and the center of the second end face and connects the first end face and the second end face. A first major cutting edge is formed on the outer edge of the first end face. A first flank facing the first major cutting edge is formed between the first major cutting edge and the peripheral side surface and has a negative clearance angle α with respect to the peripheral side surface. The peripheral side surface includes a first side surface facing the first flank. Between the first flank and the first side surface, a recess line is formed to extend along a virtual edge line where a virtual plane extending from the first flank and a virtual plane extending from the first side surface cross each other, and the recess line is formed with a notch on the virtual edge line.

Provided is a cutting insert which is resistant to breakage and can stably be restrained. A cutting insert configured as a vertically mounted insert has a first rake face adjacent to a first major cutting edge, a second rake face adjacent to a second major cutting edge, a restraint surface located further inward than the first and second rake faces to come into contact with a tool body when a second end surface is used, and a reinforcing portion projecting from the restraint surface. The reinforcing portion has a third projecting ridge provided to extend between the first and second rake faces and halve the restraint surface, a first projecting ridge connected to one end of the third projecting ridge to extend so as to cover at least a portion of a boundary between the first rake face and the restraint surface, and a second projecting ridge connected to another end of the third projecting ridge so as to cover at least a portion of a boundary between the second rake face and the restraint surface.