A cutting insert includes a body made of a ceramic material. The body has a first surface, a second surface and at least one flank surface extending between the first surface and the second surface. The first surface includes a chip forming feature extending in a radially outwardly direction to a cutting edge and extending in a radially inwardly direction to an inner edge. The chip forming feature includes a front wall that slopes downward from the cutting edge radially inward toward a rounded bottom surface and a back wall that slopes upward from the rounded bottom surface radially inward to the inner edge. The chip forming feature can include an optional land surface between the cutting edge and the front wall.

A cutting part of a cutting insert may include a first surface including a corner, a first side, a first region, a second region and a third region. The first region may be located along the corner and the first side. The second region may be located at a more inner part than the first region. The third region may be located at a more inner part than the second region. A boundary between the corner and the first side may be a first point. A boundary between the first region and the second region may be a second point in a cross section that passes through the first point and is orthogonal to the first side. An imaginary straight line passing through the first point and the second point may be a first imaginary straight line. The first imaginary straight line may intersect with the third region.

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

A cutting insert includes a leading cutting edge having a rake angle in the range of 20 to 35 in a central region in a width direction; and a rake face having a breaker groove formed in the central region in the width direction and land portions formed in both end regions in the width direction. The land portions have a rake angle smaller than the rake angle in the central region in the width direction. The breaker groove includes opposing side faces separated from each other by a distance that decreases with increasing distance from the leading cutting edge and four shoulder portions of the same height that are formed on the opposing side faces at positions above the land portions, two of the shoulder portions being closer to the leading cutting edge and to outer sides in the width direction than the other two shoulder portions are.

A rotary cutting tool insert according to one embodiment of the present invention includes: an annular rake face provided with at least one recess portion; and a cutting edge formed at an outer circumference of the rake face, the recess portion having a width of more than or equal to 1.2 mm and less than or equal to 3.0 mm in a circumferential direction of the rake face, a distance between the cutting edge and an end of the recess portion at the outer circumference side of the rake face being more than or equal to 0.1 mm and less than or equal to 0.5 mm. According to the rotary cutting tool insert according to the one embodiment of the present invention, roughness of a processed surface and vibration due to a cutting process can be prevented.

A cutting insert of one aspect includes a top surface including a corner portion and a pair of side portions each adjacent to the corner portion, a bottom surface, a side surface located between the top surface and the bottom surface, and a corner cutting edge disposed at the corner portion. In such a cutting insert, the top surface includes a first rake surface located along the corner cutting edge, a raised portion located farther on the inner side than the first rake surface, and a second rake surface located between the corner cutting edge and the raised portion. Moreover, a rake angle at a first region of the second rake surface corresponding to a center of the corner cutting edge is greater than a rake angle at a second region of the second rake surface located beside the first region.

A cutting insert for high-efficiency cutting is disclosed. The cutting insert includes an upper surface (110a), a lower surface (HOb), side surfaces (114) and corner side surfaces (116), which connect the side surfaces to each other. A circular opening is formed through the central portions of the upper and lower surfaces. In the cutting insert, cutting edges are formed by respective junctions between one of the upper and lower surfaces and the side surfaces and between one of the upper and lower surfaces and the corner side surfaces. The cutting edges comprise three corner cutting edges (122), six major cutting edges (124), which extend from opposite ends of the corner cutting edges towards the neighbor corner cutting edges, and three minor cutting edges (126), which are connected between the major cutting edges. Furthermore, the cutting edges may be formed on both the upper surface and the lower surface.

A cutting tool includes a cutting edge member. The cutting edge member forms a corner portion. The cutting edge member includes a cutting edge formed at the intersection of a rake surface and a flank, at least two breaker wall surfaces and at least one convex portion. The cutting edge includes a first cutting edge and a second cutting edge connected thereto. The second cutting edge is situated at the corner portion. Each breaker wall surface is formed to extend along the cutting edge. The convex portion is formed between the two breaker wall surfaces spaced from each other to protrude relatively toward the cutting edge side. A part of the convex portion is situated around a connecting portion of the first and second cutting edges.

Chip discharge during high-feed machining and low-feed machining particularly in a high-depth-of-cut state or the like is improved so as to provide adaptability to a wide range of cutting conditions during low depth and high depth cutting and during low-feed and high-feed machining and allow so-called freedom of feed during cutting to be improved. A cutting insert includes a cutting edge body and a substrate to which the cutting edge body is joined. The cutting edge body has a prismatic shape having a longitudinal direction and a lateral direction perpendicular to the longitudinal direction and includes a cutting edge formed on an intersecting edge between a peripheral side surface and an upper surface of the cutting edge body having the prismatic shape and a recessed part formed at a position on the upper surface of the cutting edge body which is more distant from the intersecting edge than from the cutting edge. The substrate has a projected part upwardly projecting from the upper surface of the cutting edge body.

A cutting insert according to an embodiment of the present invention has a body section and a cutting section located closer to a front end side than the body section. The cutting section has an end cutting edge located along an intersection of an upper surface and a side surface, a recess located from the end cutting edge toward the body section, and a pair of protrusions opposed to each other with the recess interposed therebetween. The pair of protrusions has a first protrusion and a second protrusion located on the first protrusion. The first protrusion has a first inclined surface that is inclined upward and approaches another one of the pair of protrusions as going from the front end side toward the rear end side. A periphery of the second protrusion which is close to the front end side has a convex curvilinear shape in a top view.