A turning insert includes a head portion connected to a stem portion. A CBN cutting edge includes a surface generating cutting edge and two major cutting edge portions, such that each major cutting edge portion forms an angle of 5-20° in relation to a tangent line of the cutting edge at a forward point of the cutting edge.

A sintered body of the present invention is a sintered body including a first material and cubic boron nitride. The first material is partially-stabilized ZrO.sub.2 including 5 to 90 volume % of Al.sub.2O.sub.3 dispersed in crystal grain boundaries or crystal grains of partially-stabilized ZrO.sub.2.

A sintered material includes a first phase and a second phase, wherein the first phase is composed of cubic boron nitride particles, and the following relational expressions are satisfied when more than or equal to two cubic boron nitride particles adjacent to and in direct contact with each other among the cubic boron nitride particles are defined as a contact body, Di represents a length of an entire perimeter of the contact body, n represents the number of contact locations at which the cubic boron nitride particles are in direct contact with each other, d.sub.k represents a length of each of the contact locations, and Σd.sub.k (where k=1 to n) represents a total length of the contact locations: Dii=Di+(2×Σd.sub.k (where k=1 to n)); and [(Dii−Di)/Dii]×100≤50.

The invention relates to a four-edged drill having two long main cutting edges, arranged in a point-symmetric manner with regard to the axis of rotation, which each extend from an outer circumferential cutting corner to a chisel edge in the middle of the drill tip, and two short main cutting edges, arranged in a point-symmetric manner with regard to the axis of rotation, which each extend from an outer circumferential cutting corner in the direction of the middle of the drill tip. According to the invention, each long main cutting edge has an outer partial cutting edge, extending from the cutting corner as far as a shoulder, and an inner partial cutting edge, extending from the shoulder as far as the chisel edge, said inner partial cutting edge having a greater cutting height (Δx) than the outer partial cutting edge and the short main cutting edges.

A cutting tool, including a cutting edge portion composed of a cubic boron nitride sintered material, wherein the cutting edge portion has: a flank face; a rake face contiguous to the flank face; and a cutting edge positioned on a ridgeline of the flank face and the rake face, an arithmetical mean height Sa of the flank face is 0.5 μm or more and 3.0 μm or less, the Sa is measured in accordance with ISO25178-2:2012, and an oxygen concentration of the flank face is 10 mass % or more and 50 mass % or less.

A cutting tool, comprising a substrate having a cutting surface and a coating adhered to the cutting surface in a solid state, wherein the coating includes a soft metal and is capable of melting and functioning as an in-situ liquid lubricant when the cutting tool is applied in a machining operation. Also, a method of applying a coating to a cutting tool, comprising receiving a premachining workpiece, the premachining workpiece formed of a coating material including a soft metal; and machining the premachining workpiece with the cutting tool such that a layer of the coating material adheres to a cutting surface of the cutting tool in a solid state.

A cutting tool, comprising a substrate having a cutting surface and a coating adhered to the cutting surface in a solid state, wherein the coating includes a soft metal and is capable of melting and functioning as an in-situ liquid lubricant when the cutting tool is applied in a machining operation. Also, a method of applying a coating to a cutting tool, comprising receiving a premachining workpiece, the premachining workpiece formed of a coating material including a soft metal; and machining the premachining workpiece with the cutting tool such that a layer of the coating material adheres to a cutting surface of the cutting tool in a solid state.

The invention relates to a four-edged drill having two long main cutting edges, arranged in a point-symmetric manner with regard to the axis of rotation, which each extend from an outer circumferential cutting corner to a chisel edge in the middle of the drill tip, and two short main cutting edges, arranged in a point-symmetric manner with regard to the axis of rotation, which each extend from an outer circumferential cutting corner in the direction of the middle of the drill tip. According to the invention, each long main cutting edge has an outer partial cutting edge, extending from the cutting corner as far as a shoulder, and an inner partial cutting edge, extending from the shoulder as far as the chisel edge, said inner partial cutting edge having a greater cutting height (x) than the outer partial cutting edge and the short main cutting edges.

A cutting element for a tool to create a helically extending, trapezoidally undercut groove in a cylindrical surface of a bore. The cutting tool, preferably configured as a cutting insert, has groove-cutting teeth to create a symmetrically cross-sectioned groove which are arranged in series in a division harmonized with the pitch of the groove to be created. These groove-cutting teeth comprise at least one pre-machining tooth to create and machine a base groove and several trapezoidal teeth following the at least one pre-machining tooth, which have a tooth head profile which expands trapezoidally in cross-section in the vertical direction of the tooth with two flanks delimiting a flank angle for further machining the base groove to a trapezoidally undercut final cross-section. The flank angle delimited by the two flanks increases from at least one trapezoidal tooth to a following trapezoidal tooth to a defined final dimension.

A turning insert includes a head portion connected to a stem portion. A CBN cutting edge includes a surface generating cutting edge and two major cutting edge portions, such that each major cutting edge portion forms an angle of 5-20 in relation to a tangent line of the cutting edge at a forward point of the cutting edge.