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.

A cutting insert of the present disclosure includes a first surface, a second surface, and a cutting edge. The first surface includes a corner part, and a first side and a second side each extending from the corner part. The second surface connects to the first surface. The cutting edge is located at a region where the first surface intersects with the second surface. The cutting edge includes a first cutting edge located at the first side, a second cutting edge located at the second side, and a third cutting edge located at the corner part. The first cutting edge and the third cutting edge are provided with a honing. A honing width of a side of the second cutting edge in the third cutting edge decreases as going away from the first cutting edge and then approaching the second cutting edge.

A cutting tool including a substrate and a coating film disposed on the substrate, wherein the cutting tool includes: a rake face, a flank face contiguous to the rake face; and a cutting edge region composed of a boundary part between the rake face and the flank face, wherein the coating film includes a TiSiCN layer, the TiSiCN layer has: a first TiSiCN layer positioned in the rake face; and a second TiSiCN layer positioned in the cutting edge region, the first TiSiCN layer has a composition of Ti.sub.(1-Xr)Si.sub.XrCN, the second TiSiCN layer has a composition of Ti.sub.(1-Xe)Si.sub.XeCN, and the Xr and the Xe each represent 0.010 or more and 0.100 or less, and satisfy a relationship of Xr?Xe?0.003.

A throwaway insert includes a base and a cutting edge member. The cutting edge member includes: a rake face; a flank face extending to cross the rake face; a first connecting face connecting the flank face to a side surface of the base and extending to cross the rake face; and a first ridgeline formed by the rake face and the flank face and serving as a cutting edge. When viewed in a plan view from the upper surface of the base, the flank face and the first connecting face are located external to the base. A second ridgeline formed by the rake face and the first connecting face crosses the first ridgeline at an obtuse angle.

A cutting tool according to an aspect of the present invention is a cutting tool for cutting a rotationally symmetrical surface of a rotating workpiece. The cutting includes the step of feeding the cutting tool in a direction inclined with respect to a rotational axis of the rotationally symmetrical surface, while holding the cutting tool in contact with the rotationally symmetrical surface. In the step of feeding the cutting tool, the cutting tool has a point that is in contact with the rotationally symmetrical surface and the point shifts as the cutting tool is fed. The cutting tool includes: a rake face; a flank face; and a cutting edge connecting the rake face and the flank face. The cutting edge as seen from above the flank face has a shape including at least one arc, and the arc has a radius of curvature of not less than 100 mm and not more than 500 mm.

A cutting insert may include a first surface, a second surface, a third surface, and a land surface. The first surface may include a first corner and a first side. The land surface may be located between the first surface and the third surface. The land surface may include a first land surface connecting to the first corner, and a second land surface connecting to the first side. A width of the first land surface in a front view as viewed from a side of the first surface may be a first width, the first width at an end portion on a side of the second land surface may be larger than the width at a part connecting to a midportion of the first corner.

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.

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.

An insert based on an aspect includes a first surface having a corner portion, a second surface, a third surface, and a cutting edge located on at least part of a portion on which the first surface and the third surface intersect. The cutting edge is provided with a first cutting edge located on the corner portion and a second cutting edge adjacent to the first cutting edge, and the third surface is provided with a first portion located along the first cutting edge and a second portion located along the second cutting edge. Additionally, the second portion includes a first region having a first end portion and a second end portion, and a second region having a third end portion and a fourth end portion. An inclination angle 212 at the second end portion is greater than an inclination angle 211 at the first end portion, and an inclination angle 222 at the fourth end portion is smaller than an inclination angle 221 at the third end portion.

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).