Abstract: A first lateral surface of a cutting insert includes a first region, a second region, and a third region. The first region includes a first upper region inclined outward, and a first lower region that is parallel to a central axis. The second region includes a second upper region inclined inward, and a second lower region that is parallel to the central axis. The third region includes a third upper region inclined outward, a third lower region, and a concave part. The third lower region is located more outside than the third upper region and is parallel to the central axis. The concave part is located between the third upper region and the third lower region.

Abstract: A cutting insert in a non-limiting aspect of the present disclosure may include an upper surface having a polygonal shape and including a first side, a lower surface, and a lateral surface. The lateral surface may include a first lateral surface located between the first side and the lower surface. The first lateral surface may include a first region that is flat. The first region may include a first central region, a first upper region and a first lower region. The first upper region may be located closer to the upper surface than the first central region, and may have a larger width than the first central region. The first lower region may be located closer to the lower surface than the first central region, and may be a larger width than the first central region.

Abstract: A cutting tool may include a main body extended from a first end to a second end. The main body may be rotatable around a rotation axis. The main body may include a first cutting edge, a second cutting edge, a first flute and a second flute. The first flute may be extended from the first cutting edge toward the second end. The second flute may be extended from the second cutting edge toward the second end. The first flute may include a first hole located in the main body. The second flute may include a second hole located in the main body. The first hole may have a circular shape and the second hole may have a long narrow shape in a circumferential direction of the rotation axis in a cross section orthogonal to the rotation axis.

Abstract: A cutting tool may include a main body extended from a first end to a second end. The main body may be rotatable around a rotation axis. The main body may include a first cutting edge, a second cutting edge, a first flute and a second flute. The first flute may be extended from the first cutting edge toward the second end. The second flute may be extended from the second cutting edge toward the second end. The first flute may include a first hole located in the main body. The second flute may include a second hole located in the main body. The first hole may have a circular shape and the second hole may have a long narrow shape in a circumferential direction of the rotation axis in a cross section orthogonal to the rotation axis.

Abstract: A cutting insert may include a first surface and a second surface. The first surface may include a first side, a first corner, a second corner, and a breaker part. The breaker part may include a first segment, a second segment, and a third segment. The first segment may be an inclined surface inclined so as to approach the second surface as going away from the first side. The third segment may be an inclined surface inclined so as to separate from the second surface as going away from the second segment. In a front view of the first surface, a maximum value at a side of the second corner may be greater than a maximum value at a side of the first corner in a distance from the first side to a top portion of the third segment on an orthogonal line with respect to the first side.

Abstract: A cutting insert may include a first surface and a second surface. The first surface may include a first side, a first corner, a second corner, and a breaker part. The breaker part may include a first segment, a second segment, and a third segment. The first segment may be an inclined surface inclined so as to approach the second surface as going away from the first side. The third segment may be an inclined surface inclined so as to separate from the second surface as going away from the second segment. In a front view of the first surface, a maximum value at a side of the second corner may be greater than a maximum value at a side of the first corner in a distance from the first side to a top portion of the third segment on an orthogonal line with respect to the first side.