Abstract: A rotary cutting tool according to the present disclosure is rotatable about an axial line and includes a rake face and a flank face. The flank face is contiguous to the rake face. A ridgeline between the rake face and the flank face constitutes a cutting edge. In a cross section perpendicular to the axial line, the rake face is constituted of a plurality of straight line portions.

Abstract: A cubic boron nitride sintered material includes: more than or equal to 80 volume % and less than or equal to 96 volume % of cubic boron nitride grains; and a binder, wherein the binder includes tungsten carbide, cobalt, and an aluminum compound, and Ha/Hb?0.40 is satisfied, where Hb represents a hardness of the cubic boron nitride sintered material and Ha represents a hardness of the cubic boron nitride sintered material after performing acid treatment onto the cubic boron nitride sintered material to substantially remove the binder in the cubic boron nitride sintered material.

Abstract: A cutting insert includes a substrate and a cutting-edge insert. The substrate has, in a thickness direction of the substrate, a bottom surface, and a top surface opposite to the bottom surface. The top surface has a polygonal shape composed of a plurality of sides in a plan view as seen along the thickness direction. The top surface is provided with a projection projecting to a side opposite to the bottom surface along the thickness direction. The projection has a through-hole passing through the substrate along the thickness direction. The projection has a side surface contiguous to the top surface. The side surface is composed of a curved line protruding to a side opposite to the through-hole in the plan view as seen along the thickness direction.

Abstract: A cBN sintered material comprising cBN particles and a binder phase, in which the binder phase contains AlN and AlB2, a content proportion of cBN particles is 70 to 97 vol %, cBN sintered material has a volume resistivity up to 5×10?3 ?cm, a rate of a peak intensity derived from Al with respect to a peak intensity derived from cBN particles is less than 1.0%, cBN particles include fine particles and coarse particles, coarse particles optionally include ultra-coarse particles, with respect to the entire cBN particles, a content proportion ? of fine particles is from 10 vol %, a content proportion ? of coarse particles is from 30 vol %, a content proportion ? of ultra-coarse particles is 25 vol % or less, and a total of the content proportion ? of fine particles and the content proportion ? of coarse particles is 50 to 100 vol %.

Abstract: A cutting tool is rotatable about an axis line, and includes a main body portion, a cutting insert, and a plurality of anti-vibration members. The main body portion has an inner circumferential surface and an outer circumferential surface opposite to the inner circumferential surface. The cutting insert is attached to at least one of the inner circumferential surface and the outer circumferential surface. Each of the plurality of anti-vibration members is provided at the main body portion. Each of the plurality of anti-vibration members includes a weight member composed of a material having a specific gravity larger than a specific gravity of a material of the main body portion.

Abstract: A cubic boron nitride sintered material comprising cubic boron nitride grains, a binder phase, and a void, in which a percentage of the cubic boron nitride grains based on the total of the cubic boron nitride grains and the binder phase is 40 vol % to 70 vol %, a percentage of the binder phase based on the total of the cubic boron nitride grains and the binder phase is 30 vol % to 60 vol %, the binder phase includes 10 vol % to 100 vol % of aluminum oxide grains, an average grain size of the aluminum oxide grains is 50 to 250 nm, the cubic boron nitride sintered material comprises 0.001 vol % to 0.100 vol % of one or more first voids, and at least one portion of each of the first voids is in contact with the aluminum oxide grains.

Abstract: The cubic boron nitride sintered material is a cubic boron nitride sintered material comprising: cubic boron nitride particles in an amount of 70 vol % or more and less than 100 vol %, and a bonding material, wherein the bonding material includes an aluminum compound, and includes cobalt as a constituent element; the cubic boron nitride sintered material has a first region in which a space between adjacent cubic boron nitride particles is 0.1 nm or more and 10 nm or less; and when the first region is analyzed by using an energy dispersive X-ray analyzer equipped with a transmission electron microscope, the atom % of aluminum in the first region is 0.1 or more.

Abstract: A cutting tool includes a substrate and a coating film that is disposed on the substrate, wherein the coating film includes a first layer composed of metal tungsten and hexagonal ditungsten carbide, and the first layer has an elastic deformation rate of 43.0 or more and 58.0 or less.

Abstract: A drill has a first main body portion and a second main body portion. The first main body includes a chip discharging surface, a flank face, and an outer peripheral surface. A ridgeline between the chip discharging surface and the flank face constitutes a cutting edge. The chip discharging surface has an auxiliary flute surface provided in a form of a helix around a center axis, the auxiliary flute surface being contiguous to the cutting edge, the auxiliary flute surface being recessed in a direction opposite to a rotation direction of the drill. An auxiliary cutting edge portion has a first end portion and a second end portion. When viewed in a direction along the center axis, a value obtained by dividing the maximum value of the diameter of the second main body portion by the diameter of the first main body portion is 1.5 or more.

Abstract: A coolant supply mechanism is attachable to a cutting insert. The cutting insert has a first bottom surface, a first upper surface, and a first side surface. The first upper surface includes a corner portion that is located at a corner of the first upper surface when viewed in a plan view and that is contiguous to the first side surface so as to form a cutting edge, and a center portion located adjacent to the corner portion on a side opposite to the cutting edge when viewed in a plan view. The first upper surface is depressed toward the first bottom surface side at the center portion.

Abstract: A cutting tool including a base material and a hard layer provided on the base material, in which the hard layer is composed of a compound represented by TiaAlbBcN, an atomic ratio a is 0.25 or more and less than 0.55, an atomic ratio b of is 0.45 or more and less than 0.75, an atomic ratio c of is more than 0 and 0.1 or less, a sum of the atomic ratio a, the atomic ratio b and the atomic ratio c is 1, a ratio I(200)/I(002) of an intensity I(200) of an X-ray diffraction peak of a (200) plane to an intensity I(002) of an X-ray diffraction peak of a (002) plane in the hard layer is 2 to 10, and a full width at half maximum of the X-ray diffraction peak of the (002) plane is 2 degrees to 8 degrees.