An insert according to an embodiment includes an upper surface including a corner part, a lower surface, a side surface, and a cutting edge. The cutting edge includes a first cutting edge located at the corner part, a second cutting edge adjacent to the first cutting edge, a third cutting edge adjacent to the second cutting edge, and a fourth cutting edge adjacent to the third cutting edge. Each of the third cutting edge and the fourth cutting edge has a concave curvilinear shape extending downward in a side view. A radius of curvature of the fourth cutting edge is smaller than a radius of curvature of the third cutting edge.

A cutting insert has a bottom supporting surface, a center cutting edge, two secondary cutting edges, realized on both sides of the center cutting edge and offset in relation to the center cutting edge, and two transition edges connecting the center cutting edge to the secondary cutting edge adjacent in each case. The two secondary cutting edges are realized in each case vertically offset and, where applicable, also offset in depth with respect to the center cutting edge and are laterally spaced from the center cutting edge. The transition edges, in each case in a non-edge-overlapping region, have at least over a portion an inclination n where 2n20 in relation to a height direction which extends at right angles with respect to a main extension plane of the supporting surface.

A cutting insert includes a land and a breaker flute on a rake face, the land providing a cutting edge by intersecting a flank face. The breaker flute includes breakers. A width T of a portion of the land that extends along a portion of the cutting edge that is at a round corner portion is 0.05 mm<T<0.15 mm. A plurality of crest portions each extending over the entirety of the portion of the cutting edge that is at the round corner portion are provided on a sloping surface of the breaker flute that is on a land side. The crest portions are arranged side by side in a depth direction of the breaker flute. A rake angle of at least one of inclined surfaces that form each of the crest portions is expressed as >20.

Provided is a drill insert to ensure sufficient chipping resistance with respect to a large cutting load, which is detachably attached to a distal portion of a drill body which is rotated around an axis, in which a polygon face of a polygonal plate-shaped insert body is a rake face, a side face disposed around the rake face is a flank face, a cutting blade is formed on a ridge portion in which the rake face and the flank face intersect each other, the cutting blade includes a honing face, the honing face includes a first convex curved face continuous with the rake face and a second convex curved face continuous with the flank face, and in a cross section orthogonal to the cutting blade, a curvature radius of the first convex curved face is larger than a curvature radius of the second convex curved face.

A cutting insert may include an upper surface, a lower surface, a lateral surface and a cutting edge. The upper surface may include a first corner, a first side, a second side and a rake surface. The cutting edge may include a first cutting edge located on the first corner, and a second cutting edge located on the first side. The first cutting edge may include a first part. The first part may be located between a midportion of the first corner and the first side, and may come closer to a reference plane as going away from the first side. The rake surface may include a first region located along the first part. A rake angle in the first region may become smaller as coming closer to the midportion of the first corner.

Disclosed is a cutting insert having a generally polygonal primary body having a primary body base connected to an opposing and similarly-shaped body face through a plurality of primary flank portions extending there between. The cutting insert further includes at least one cutting protrusion extending away from at least one of the primary flank portions, and merging therewith. The cutting protrusion includes a rake face coplanar and extending away from the adjacent primary flank portions, and an edge portion extended towards a cutting flank portion. The cutting protrusion further includes a tip flat extending between a rake front from a protrusion tip towards a rake root portion, adjacent one of the primary flank portions.