A cutting insert of a substantially horizontal cylindrical segment shape and having top and bottom surfaces with a circular segment shape. The cutting insert has a convex side and a flat side, a top cutting edge which is formed where the convex side and the top surface meet, and a bottom cutting edge which is formed where the convex side and the bottom surface meet. The cutting insert includes a hole extending from the convex side towards the flat side. The hole is positioned at a center of a surface of the flat side.

A cutting tool includes a substrate of cemented carbide having hard constituents in a metallic binder. The hard constituents include WC. The WC content in the cemented carbide is 80-95 wt %. The cemented carbide has a Fe+Ni+Co+Cr content of 3-13 wt %, an atomic ratio of 0.05<Fe/(Fe+Ni+Co+Cr)<0.35, an atomic ratio of 0.05<Ni/(Fe+Ni+Co+Cr)<0.35, an atomic ratio of 0.05<Co/(Fe+Ni+Co+Cr)<0.35 and an atomic ratio of 0.05<Cr/(Fe+Ni+Co+Cr)<0.35. The crack resistance W measured on the rake face of the cutting tool is at least 25% higher than the W measured on a cross section of the bulk area of the cutting tool.

A cutting insert according to one embodiment includes: a rake face; a flank face continuous to the rake face; and a cutting edge constituted of a ridgeline between the rake face and the flank face. A coolant flow path is provided inside the cutting insert. One end portion of the coolant flow path opens in the flank face to form a coolant ejection hole. The flank face is provided with a coolant guide groove extending from the coolant ejection hole toward the cutting edge with a base end portion of the coolant guide groove being connected to the coolant ejection hole and with a front end portion of the coolant guide groove being disposed at a position close to the cutting edge relative to the base end portion.

A cutting element, which is configured for the machining of a non-metallic composite material composed of a matrix and particles held together by the matrix, has a flank face, a rake face and a cutting edge which is coated with an edge coating and via which the flank face and the rake face are connected to one another, with which the non-metallic composite material can be machined in an improved fashion. The cutting edge within a cutting edge section thereof is curved in such a way that the cutting edge immediately beneath the edge coating in a section in a section plane that is perpendicular to the cutting edge has, at every point of the cutting edge section, a local radius of curvature which is greater than or equal to 10 μm and less than or equal to 80 μm.

A drill bit for chiseling stone includes an impact face at an insertion end of the drill bit, a hollow shank, where a delivery passage is defined within the hollow shank, and a drill head, where the drill head has, at a front end of the drill head, a cutting edge, an intake opening, and an intake passage. The intake passage connects the intake opening to the delivery passage. A cross section of the intake passage increases from the intake opening to the delivery passage.

When forming a first preliminary flute on a PCD layer of a columnar body, electrical discharge machining is performed by setting the electrode orientation so that the first twist angle is α. Next, when forming a second preliminary flute on a substrate of the columnar body and a round bar, the grinding process is performed by setting the grinding orientation and direction for a diamond whetstone so that a second twist angle is larger than the first twist angle.

A tungsten-carbide-based hard material includes the following components: tungsten carbide with an average particle size of 0.1-1.3 μm; 1.0-5.0 wt. % (Co+Ni), with a ratio of Co/(Co+Ni) in wt. % of 0.4≤Co/(Co+Ni)≤0.95; 0.1-1.0 wt. % Cr, with a ratio of Cr to (Co+Ni) in wt. % of 0.05 Cr/(Co+Ni) 0.20; 0.01-0.3 wt. % Mo; and 0.02-0.45 wt. % Me, where Me represents one or more elements from the group Ta, Nb, Hf and Ti, preferably Ta and/or Nb; and wherein 0.01≤Me/(Co+Ni)≤0.13.

A component obtainable by a process which includes providing a composition and sintering the composition at a sintering temperature of from 1250° C. to 1400° C. for a period of from 3 to 15 minutes. The composition includes hard material particles with an inner core of fused tungsten carbide and an outer shell of tungsten carbide, and a binder metal selected from Co, Ni, Fe and alloys with at least one metal selected from Co, Ni and Fe.

A cutting tool includes: a main body portion composed of a cemented carbide; and a front end portion composed of a binderless cubic boron nitride polycrystal, the front end portion being joined to the main body portion. In an axial direction along a rotation axis of the main body portion, the main body portion has a first end and a second end opposite to the first end. The front end portion has a neck portion and an edge portion, the neck portion protruding from the second end along the axial direction, the edge portion being continuous to the neck portion, the edge portion being located at a location distant away from the second end relative to the neck portion in the axial direction. In the axial direction, the neck portion has a third end on the edge portion side and a fourth end opposite to the third end.

A method for manufacturing a cutting tool includes: the cutting tool comprising a tool body made of a sintered alloy, a hard coating which is disposed on an outer surface of the tool body and has at least a layer formed of any of a carbide, a nitride, and a carbonitride, or a composite compound thereof, and a cutting edge which is formed at a ridge portion of the tool body and includes a portion of the hard coating located at the ridge portion, a laser peening step of directly irradiating the hard coating with a pulsed laser having a pulse width of 100 ps or less to apply compressive residual stress to the hard coating and a surface region of the tool body.