A cutting insert according to one aspect has a flat plate shape including a first main surface having a polygonal shape, a second main surface located opposite to the first main surface, and an outer peripheral surface located between the first main surface and the second main surface. The cutting insert includes a cutting portion located in regions including at least a corner portion of the first main surface, and a main body portion located in a region other than the corner portion. A thickness of the main body portion is larger than a thickness of the cutting portions, and the main body portion includes a recessed portion or a protruding portion located in the outer peripheral surface thereof.

A cutting tool which allows for fracture resistance and cutting resistance to be improved at the same time is provided. A cutting tool according to the present invention is a cutting tool 1 comprising an end surface 10, first and second side surfaces 13, 14 which intersect with the end surface 10, a first cutting edge 20a in an intersecting edge between the end surface 10 and the first side surface 13, and a second cutting edge 20b in an intersecting edge between the end surface 10 and the second side surface 14, wherein: the first cutting edge 20a has a first honing surface 21a; and the second cutting edge 20b has a second honing surface 21b. A cross-sectional shape of the second honing surface 21b is different from a cross-sectional shape of the first honing surface 21a.

A cutting element has a cutting head and a shaft. The cutting head is carried by the shaft and protrudes over the shaft transversely relative to a longitudinal extent of the shaft. The cutting head has a cutting edge, the cutting edge follows a circle segment with a circle center at a side of the shaft located in a virtual cutting head plane and is constructed symmetrically, when viewed in a direction perpendicular to the cutting head plane, with respect to a virtual cutting edge axis of symmetry which is contained in the cutting head plane. The cutting head has a chip guiding structure. The chip guiding structure is associated with the cutting edge, has a chip guiding groove and a plurality of chip guiding elements. Each chip guiding element has a longitudinal rib and a transverse rib.

Provided is a cutting tool that simultaneously improves both fracture resistance and wear resistance. The cutting tool according to the present invention has an end surface, a peripheral side surface intersecting with the end surface, and a cutting edge in an intersecting ridge part along the end surface and the peripheral side surface, and when first and second points A and B are defined on the cutting edge, the first point A protrudes further toward an outer side of the cutting tool than the second point B. The cutting edge has a honing surface. The honing surface has a portion, the width of which gradually increases from the first point A toward the second point B.

Provided is a cutting tool in which one end side of a protruding cutting edge is sharpened while wear resistance is improved. The cutting tool of the present invention includes an end surface, a peripheral side surface that intersects the end surface, and a cutting edge in an intersecting ridgeline portion between the end surface and the peripheral side surface. When first and second points (A and B) are set on the cutting edge, the first point (A) protrudes further toward an outer side of the cutting tool than the second point (B). The cutting tool has a coating film on its surface. The cutting edge has a portion in which the thickness of the coating film gradually increases toward the second point (B) from the first point (A).

Inclined surfaces are formed on a rake face and a recessed groove is formed in the central portion between the inclined surfaces. A groove width of the recessed groove gradually increases from the position of the end cutting edge toward the rear, then gradually decreases such that the recessed groove has a narrowest portion at a position P2 forward of the position P3 of an upper end of a breaker wall and rearward of a positive rake angle rear end position P1, and then gradually increases toward the rear up to the position P3 of the upper end of the breaker wall. The dimensional relation W1<W2<W3 holds, where W1 is the groove width at the end cutting edge, W2 is the groove width at the narrowest portion, and W3 is the groove width at the position P3 of the upper end of the breaker wall.

In an embodiment, a cutting insert includes an upper surface, a front end surface, and a front cutting edge. The upper surface includes a first protrusion and a second protrusion, and a first surface, a second surface, and a third surface, each of which is located between the first protrusion and the second protrusion. The first surface is inclined downward at a first inclination angle. The second surface is inclined upward at a second inclination angle. The third surface is inclined upward at a third inclination angle. The second surface is located lower than an upper end of each of the first protrusion and the second protrusion. The third surface extends further upward than the upper end of each of the first protrusion and the second protrusion. The third inclination angle is smaller than the second inclination angle.

A cutting tool includes a two-way indexable cutting insert retained in a tool holder by a clamping member. The cutting insert has a tetrahedral basic shape and includes two cutting edges at opposite ends of thereof. The insert holder includes a forwardly located mounting portion that includes three spaced apart mounting jaws which together define an insert receiving pocket having a pocket opening. The clamping member is attached to the insert holder body so that a clamping portion of the clamping member protrudes into the pocket opening. When the cutting insert is releasably attached to the insert holder in a fastened position of a cutting tool, the cutting insert is located in the insert receiving pocket and clampingly engaged therein by the clamping portion.

A cutting tool having a tool holder, cutting insert and clamping member. The tool holder includes an elongated supporting surface extending in a rearward-to-forward direction. The cutting insert has a central portion and three cutting portions, the central portion having two opposing side surfaces and three spaced apart locating surfaces defining a first imaginary triangle. The cutting insert is indexable about a central axis intersecting the two side surfaces. Each locating surface intersects two of three bisector planes containing the central axis and bisecting respective corners of the first imaginary triangle, and the cutting edge of each cutting portion is located entirely outside of the first imaginary triangle. In each index position the clamping member is located entirely rearward of a first vertical plane containing the central axis and perpendicular to the rearward-to-forward direction, and one of the locating surfaces is in clamping contact with the supporting surface.

A cutting insert includes a split cutting edge, formed at an intersection of the insert forward surface and the insert upper surface, the split cutting edge includes an axially leading cutting edge and an axially trailing cutting edge. An undercut is located in the insert forward surface and interrupts the split cutting edge at an undercut edge portion that extends between the leading and trailing cutting edges. The undercut edge portion transitions into the axially trailing cutting edge at a straight trailing cutting edge portion of the trailing cutting edge.