A method for manufacturing a cutting tool according to one embodiment is a method for manufacturing a cutting tool, the cutting tool including a base material and a diamond single crystal material fixed to the base material, the diamond single crystal material having a rake face, a flank face continuous with the rake face, and a cutting edge formed by a ridgeline serving as a boundary between the rake face and the flank face. The method for manufacturing a cutting tool according to one form of the present disclosure includes a flank face irradiation step of applying a laser to the diamond single crystal material along the cutting edge from a side of the flank face. The laser has a pulse width of 110.sup.12 seconds or less and a peak output of less than 1 W in the flank face irradiation step.

A method for manufacturing a cutting tool according to one embodiment is a method for manufacturing a cutting tool, the cutting tool including a base material and a diamond single crystal material fixed to the base material, the diamond single crystal material having a rake face, a flank face continuous with the rake face, and a cutting edge formed by a ridgeline serving as a boundary between the rake face and the flank face. The method for manufacturing a cutting tool according to one form of the present disclosure includes a flank face irradiation step of applying a laser to the diamond single crystal material along the cutting edge from a side of the flank face. The laser has a pulse width of 110.sup.12 seconds or less and a peak output of less than 1 W in the flank face irradiation step.

In this diamond-coated cemented carbide cutting tool, (1) an average particle size of WC particles is 0.5 to 0.9 m, (2) (R.sub.z) being 0.5 to 1.0 m, a maximum distance between the concave and convex () is 0.5 to 1.5 m, a length (Y.sub.e) is 0.5 to 2.0 m, (3) a sum of areas of WC particles, which satisfies (L.sub.1) being 0.4 to 0.8 m, (L.sub.2) being 0.2 to 0.4 m, and (L.sub.1)/(L.sub.2) being 1.5 to 2.5, is 70 area % or more, (4) an average grain size of diamond crystals in a region of 0.5 to 1.5 m from the body interface is 0.1 to 0.3 m, and (5) columnar crystals satisfying at least one of: a ratio of crystals, which has a growth direction shifted in 10 degrees or less from the diamond film thickness direction, being 90% or more; or an orientation ratio of <110> being 30 to 70%.

In this diamond-coated cemented carbide cutting tool, (1) an average particle size of WC particles is 0.5 to 0.9 m, (2) (R.sub.z) being 0.5 to 1.0 m, a maximum distance between the concave and convex () is 0.5 to 1.5 m, a length (Y.sub.e) is 0.5 to 2.0 m, (3) a sum of areas of WC particles, which satisfies (L.sub.1) being 0.4 to 0.8 m, (L.sub.2) being 0.2 to 0.4 m, and (L.sub.1)/(L.sub.2) being 1.5 to 2.5, is 70 area % or more, (4) an average grain size of diamond crystals in a region of 0.5 to 1.5 m from the body interface is 0.1 to 0.3 m, and (5) columnar crystals satisfying at least one of: a ratio of crystals, which has a growth direction shifted in 10 degrees or less from the diamond film thickness direction, being 90% or more; or an orientation ratio of <110> being 30 to 70%.

A laser-transmitting machining tool is disclosed. The laser-transmitting machining tool has a plurality of faces including an entrance face, a rake face, a flank face connected to the rake face, a rake side face extending between the entrance face and the rake face, and a flank side face extending between the entrance face and the flank face. The connection of the rake face to the flank face defines a cutting edge. The rake face extends away from the rake side face to define a rake angle. The entrance face is configured to receive and refract a laser beam to the rake face, the flank face, and the cutting edge for causing the laser beam to refract into and heat the workpiece at a compression region extending proximate at least the rake face and a tensile region extending proximate the flank face. A system for machining a workpiece is disclosed. A method for machining a workpiece is also disclosed.

A cubic boron nitride sintered body has between 50% and 75% cubic boron nitride by volume and between 25% and 50% binder phase by volume, and inevitable impurities. The binder phase contains an Al compound and a Zr compound. The Al compound contains Al and one or more of N, O and B; and the Zr compound contains Zr and one or more of C, N, O and B. At a polished surface of the cubic boron nitride sintered body, 40% or more of the Zr compounds satisfy the ratio 0.25n/N0.8, where: N represents the number of line segments drawn radially at equal intervals from a center of gravity of a given Zr compound to a boundary with a non-Zr compound; and n represents the number among those N line segments which intersect a boundary between the given Zr compound and cubic boron nitride.

A cubic boron nitride sintered body has between 50% and 75% cubic boron nitride by volume and between 25% and 50% binder phase by volume, and inevitable impurities. The binder phase contains an Al compound and a Zr compound. The Al compound contains Al and one or more of N, O and B; and the Zr compound contains Zr and one or more of C, N, O and B. At a polished surface of the cubic boron nitride sintered body, 40% or more of the Zr compounds satisfy the ratio 0.25n/N0.8, where: N represents the number of line segments drawn radially at equal intervals from a center of gravity of a given Zr compound to a boundary with a non-Zr compound; and n represents the number among those N line segments which intersect a boundary between the given Zr compound and cubic boron nitride.

The throwaway insert includes a base and a cutting edge member. The cutting edge member includes a rake face, a flank face, a first connecting face, a second connecting face, and a first ridgeline serving as a cutting edge. The rake face includes a main surface and a first chamfer provided at an edge tip portion of the cutting edge member, the edge tip portion including an extreme tip portion of the cutting edge member. In a plan view from an upper surface of the base, the flank face, the first connecting face, and the second connecting face are located external to the base. The first chamfer is inclined relative to the main surface so as to increase a thickness of the cutting edge member as the first chamfer is closer to the main surface.

The throwaway insert includes a base and a cutting edge member. The cutting edge member includes a rake face, a flank face, a first connecting face, a second connecting face, and a first ridgeline serving as a cutting edge. The rake face includes a main surface and a first chamfer provided at an edge tip portion of the cutting edge member, the edge tip portion including an extreme tip portion of the cutting edge member. In a plan view from an upper surface of the base, the flank face, the first connecting face, and the second connecting face are located external to the base. The first chamfer is inclined relative to the main surface so as to increase a thickness of the cutting edge member as the first chamfer is closer to the main surface.

A cutting insert based on a non-limiting aspect has a first member and a second member joined to the first member. The second member has an upper surface and a side surface adjacent to the upper surface. The upper surface includes a first side, a second side and a corner. The upper surface has a first convex portion extending toward the corner, and a second convex portion extending from the first convex portion toward the first side. The second convex portion has a first end portion and a second end portion located closer to the corner than the first end portion. A first length from the first end to the first side is less than a second length from the second end portion to the first side in a top view.