Provided is a cutting method of cutting, with a diamond cutting tool, a metal material having at least a solid solution layer on a surface, the solid solution layer containing nitrogen atoms as interstitial solid solution atoms. In this method, cutting is performed in a region where a nitrogen concentration is equal to or greater than a predetermined concentration, and cutting is not performed in a region where the nitrogen concentration is less than the predetermined concentration.

A drill (1) is provided with a thinning edge (7), a gash portion (8), a coolant passage, and an oil hole (12). The thinning edge (7) is provided at a leading end portion of a body (3), and extends toward a chisel portion (9) from an inner end (51) of a cutting edge (5). A ridge line between the gash portion (8) and the flank (6) extends in a circular arc shape from an inner end of the thinning edge (7) toward an outer peripheral surface (31) of the body (3). The coolant passage is provided inside a shank and the body (3), and extends from a rear end portion of the shank toward the leading end portion of the body (3). The oil hole (12) is provided at a gash face (81) of the gash portion (8) and is an outlet of the coolant passage.

The edge portion includes an upper surface, a side surface, and a land surface. The side surface has a front side surface and a pair of lateral side surfaces. An intersection between the land surface and the front side surface forms a front cutting edge. An intersection between the land surface and each of the pair of lateral side surfaces form a corresponding one of a pair of lateral cutting edges. The edge portion contains 80 vol % or more of diamond. A chip breaker recess is provided between the upper surface and the land surface. The surfaces forming the chip breaker recess include a rake face and a breaker wall surface. The upper surface has a front edge portion opposite to the front cutting edge from the chip breaker recess. A pair of protruding portions are provided to extend from the front edge portion toward the front cutting edge.

There is provided a throw-away tip which includes a blade containing diamond and is excellent in chip processability. The throw-away tip comprises a body and a blade provided to the body and having a cutting edge, the blade containing 80% by volume or more of diamond, the blade having a land surface extending along the cutting edge, and a chip breaker having a recess located opposite to the cutting edge with the land surface therebetween, the recess having a side surface having an inclined surface that recedes continuously as a distance thereof from the land surface increases in magnitude and that has a shape identical to that of a portion of a side surface of a shape of a body of revolution.

A method for producing a diamond single crystal includes implanting an ion other than carbon into a surface of a diamond single crystal seed substrate and thereby decreasing the transmittance of light having a wavelength of 800 nm, the surface having an off-angle of 7 degrees or less with respect to a {100} plane, and homoepitaxially growing a diamond single crystal on the ion-implanted surface of the seed substrate using a chemical vapor synthesis under synthesis conditions where the ratio N.sub.C/N.sub.H of the number of carbon-containing molecules N.sub.C to the number of hydrogen molecules N.sub.H in a gas phase is 10% or more and 40% or less, the ratio N.sub.N/N.sub.C of the number of nitrogen molecules N.sub.N to the number of carbon-containing molecules N.sub.C in the gas phase is 0.1% or more and 10% or less, and the seed substrate temperature T is 850 C. or more and less than 1000 C.

A high-pressure high-temperature, HPHT, diamond tool piece and a method of producing an HPHT diamond tool piece. At least a portion of the HPHT diamond tool piece comprises an aggregated nitrogen centre to C-nitrogen centre ratio of greater than 30%. The method includes irradiating an HPHTdiamond material to introduce vacancies in the diamond crystal lattice, annealing the HPHT diamond material such that at least a portion of the HPHT diamond material comprises an aggregated nitrogen centre to C-nitrogen centre ratio of greater than 30%,andprocessing the HPHT diamond material to form an HPHT diamond tool piece.

In one aspect, cutting tools are provided comprising radiation ablation regions defining at least one of refractory surface microstructures and/or nanostructures. For example, a cutting tool described herein comprises at least one cutting edge formed by intersection of a flank face and a rake face, the flank face formed of a refractory material comprising radiation ablation regions defining at least one of surface microstructures and surface nanostructures, wherein surface pore structure of the refractory material is not occluded by the surface microstructures and surface nanostructures.

A method for manufacturing a cutting tool having a rake face, a flank face, and an edge having a ridge line interconnecting the rake face and the flank face, wherein on the flank face there is a cutting edge region from the ridge line of the edge to a point A away therefrom on the side of the flank face by a distance X, the method comprising producing and processing the flank face with a laser, the producing and processing being producing and processing the cutting edge region along the ridge line of the edge with a first laser beam having a depth of focus equal to or deeper than a width of the cutting edge region when the distance X is the width of the cutting edge region, the distance X being 0.2 mm or more and 5 mm or less.

A high-speed grooving method includes: a dummy machining step of machining a dummy groove in the surface of the workpiece by moving the cutting tool relative to the workpiece in a first direction, then turning the cutting tool 180 degrees, and subsequently further machining the dummy groove by moving the cutting tool in a second direction opposite to the first direction; a step of measuring a displacement of the cutting edge of the cutting tool, caused by the inversion of the cutting tool, from the dummy groove formed in the surface of the workpiece; a forward-stroke machining step of machining a groove with the cutting tool in the surface of the workpiece by moving the cutting tool relative to the workpiece in the first direction; a cutting tool inversion step of turning the cutting tool 180 degrees after completion of the forward-stroke machining step, thereby setting the direction of the cutting edge of the cutting tool to a direction opposite to the first direction so that the workpiece can be machined during a return stroke of the cutting tool; a correction step of correcting the relative position between the workpiece and the cutting tool so as to eliminate the displacement; and a return-stroke machining step of further machining the groove, which has been machined in the forward-stroke machining step, with the cutting tool by moving the cutting tool relative to the workpiece in the direction opposite to the first direction.

A temporary part is mounted onto the chuck of the diamond turning machine. A diamond turning tip of the diamond turning machine is used to form a reference surface on the temporary part, registering a baseline for a motion control system of the diamond turning machine. While the temporary part remains mounted to the diamond turning machine, a workpiece is mounted onto the temporary part, and the diamond tip is controlled relative to the reference surface to diamond turn a surface profile on the workpiece. Because the baseline established by the reference surface compensates for positional variations from mounting parts directly onto the chuck of the diamond turning machine, the length of the workpiece can be shaped to a designated length with a high degree of accuracy.