A cutting tool includes a substrate and a diamond layer that covers the substrate. The diamond layer includes a rake face and a flank continuous to the rake face. A ridgeline between the rake face and the flank forms a cutting edge. The substrate includes a top surface opposed to the rake face. When viewed in a direction perpendicular to the top surface, the rake face includes a plurality of protrusions. In a cross-section perpendicular to a direction of extension of the cutting edge, each of the plurality of protrusions includes an inclined portion and a curvature portion continuous to the inclined portion. In the cross-section, a height of the inclined portion in the direction perpendicular to the top surface increases as a distance from the cutting edge increases.

A cutting tool having a cutting edge member which forms at least one corner part, wherein a material for the cutting edge member is selected from either diamond, an ultrahigh-pressure sintered body containing cubic boron nitride or a PVD or CVD coating applied to a surface of the ultrahigh-pressure sintered body. At least part of an intersecting edge between an end surface of the cutting edge member and a peripheral side surface thereof is provided with a cutting edge. A chip breaker comprising a breaker wall surface is formed in the end surface of the cutting edge member. The breaker wall surface has at least one projected surface part which bulges outwardly from the cutting tool. As viewed from the end surface, the recessed surface part is arranged so as to be apart from a virtual plane A which is defined so as to divide the corner part into halves.

A polycrystalline super hard construction has a first region having a body of thermally stable polycrystalline super hard material having a plurality of intergrown grains of super hard material; a second region forming a substrate having a hard phase and a binder phase; and a third region interposed between the first and second regions. The third region includes a composite material having a first phase comprising a plurality of non-intergrown grains of super hard material, and a matrix material. A fourth region interposed between the second and third region has a major proportion having one or more components of the binder material of the second region, and one or more reaction products between the binder material of the second region and one or more components of the third region.

A cutting insert in a non-limiting embodiment may include a first surface, a second surface, a third surface and a land surface. The first surface may include a first corner and a first side extended from the first corner. The land surface may be located between the first surface and the third surface and inclined relative to the first surface and the third surface. The land surface may include a first land surface located along the first corner, a second land surface located along the first side, and a third land surface having a concave shape which is adjacent to the second land surface and located further away from the first land surface than the second land surface.

A polycrystalline diamond is formed on a substrate to form a polycrystalline diamond compact (PDC) cutter for a tool. The polycrystalline diamond has a cross-sectional dimension of at least 4 millimeters. The substrate includes tungsten carbide. An outer surface of the PDC cutter is at least partially surrounded with at least a single layer of coating by atomic layer deposition. The single layer of coating is configured to protect the PDC cutter from thermal degradation in response to exposure to a temperature greater than 700 degrees Celsius (° C.) and less than about 1050° C.

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.

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 cutting insert may include an upper surface, a lateral surface, and a cutting edge including a boundary between the upper surface and the lateral surface. The upper surface may include a first rising face that extends upward and a second rising face that is connected to an upper side of the first rising face and extends upward. The first rising face may include a first region that extends along a corner portion and a second region that extends along a side portion. The second rising face may include a third region connected to the first region and a fourth region connected to the second region. An entirety of a boundary between the first region and the third region may be positioned above the cutting edge. A boundary between the second region and the fourth region may include a portion disposed below the cutting edge.

A drill (1) is provided with a body (10) and a head (30). The body (10) is formed of cemented carbide, and the head (30) is formed of PCD. Spiral coolant passages (17, 18) are provided inside the body (10). Oil holes (25, 26) are provided in a body-side joint surface of the body (10). The oil holes (25, 26) are outlets of the coolant passages (17, 18). Coolant passages (37, 38) provided inside the head (30) extend from oil holes (45, 46) provided at a tip (31) toward a rear end (32). A head-side joint surface of the head (30) is joined to the body-side joint surface. Two oil holes are provided in the head-side joint surface. The two oil holes are inlets of the coolant passages (37, 38), and communicate with the oil holes (25, 26) in the body-side joint surface.

A diamond tool includes a diamond at least on a cutting edge including one or two or more diamond grains including a diamond phase composed of a diamond crystal structure and a graphite phase composed of a graphite crystal structure. When a ratio I.sub.π*/I.sub.σ* between an intensity of a π* peak derived from a π bond of carbon in the graphite phase and an intensity of a σ* peak derived from a σ bond of carbon in the graphite phase and a σ bond of carbon in the diamond phase is determined for the diamond grain by measuring an energy loss associated with excitation of K-shell electrons of carbon by electron energy loss spectroscopy, the ratio I.sub.π*/I.sub.σ* of the diamond grain on a surface of the cutting edge is 0.1 to 2 and a ratio I.sub.π*/I.sub.σ* of the diamond grain at a depth position of 0.5 μm from the surface of the cutting edge is 0.001 to 0.1.