A cutting tool fastener having a rotation axis and configured to secure together, and establish a fluid path between, two cutting tool members, while also accommodating angular and pivotal displacement between the two. The fastener comprising a head with at least one head opening for emitting fluid, and a body which extends from the head and has a body opening for receiving fluid to be emitted via the head opening. The head has a spherical head abutment surface with a bottom spherical seal surface zone. At least a portion of the spherical head abutment surface faces the body, and the head opening opens out to the spherical head abutment surface. The bottom spherical seal surface zone is axially located between the body and the head opening.

A cutting insert for drilling includes an upper surface, a lower surface formed on an opposite side of the upper surface, a side surface connecting the upper surface and the lower surface; a cutting edge formed at an intersection of the upper surface and the side surface, and a ridge portion formed to protrude upward from the upper surface to facilitate chip control. The ridge portion includes a ridge body spaced apart from the cutting edge and disposed at a central portion of the cutting insert for drilling; and a ridge extension portion extending from a vicinity of a corner of the ridge body in a direction parallel to the cutting edge.

A cutting edge includes a nose portion, a first cutting edge portion, and a second cutting edge portion. When a boundary between a first inclined portion and a first breaker portion, a boundary between a first step surface and a second breaker portion, a boundary between a second inclined portion and a third breaker portion, and a boundary between a second step surface and a fourth breaker portion are a first position, a second position, a third position, and a fourth position, respectively, the second position is higher than the first position and the fourth position is higher than the third position in a direction perpendicular to the seating surface, and a distance between the first position and the third position is greater than a distance between the second position and the fourth position in a direction parallel to the seating surface.

A cutting insert in the present disclosure includes an upper surface, a lower surface, a side surface, and an edge. The upper surface includes a first corner part and a second corner part. The edge is located in a region which is located between the first corner part and the second corner part. The edge includes a first edge located at a side of the first corner part, a second edge located at a side of the second corner part, and a third edge located between the first edge and the second edge. The edge has a curvilinear shape being recessed toward the lower surface in a side view. Each of a radius of curvature R1 of the first edge and a radius of curvature R2 of the second edge is smaller than a radius of curvature R3 of the third edge in a side view.

An object is to prolong the life of a cubic boron nitride cutting tool used for cutting a heat-resistant alloy. A cubic boron nitride cutting tool includes an edge tip made of a sintered cubic boron nitride compact including cubic boron nitride particles; and a base metal that holds the edge tip at a corner portion of the base metal, wherein a cutting edge formed on the edge tip of the tool has a positive rake angle.

In an embodiment, a cutting insert includes an upper surface, a front end surface, and a front cutting edge. The upper surface includes a first protrusion and a second protrusion, and a first surface, a second surface, and a third surface, each of which is located between the first protrusion and the second protrusion. The first surface is inclined downward at a first inclination angle. The second surface is inclined upward at a second inclination angle. The third surface is inclined upward at a third inclination angle. The second surface is located lower than an upper end of each of the first protrusion and the second protrusion. The third surface extends further upward than the upper end of each of the first protrusion and the second protrusion. The third inclination angle is smaller than the second inclination angle.

An insert may include a first surface, a second surface, a third surface located on a side opposite to the first surface, a cutting edge located on a ridgeline between the first surface and the second surface, and a convex part located more inside the first surface than the cutting edge. The first surface may include a groove extending from a first end part closest to the cutting edge to a second end part. The groove may include an opening located in the first surface, and a bottom surface. An imaginary plane which is orthogonal to a central axis and is located between the first surface and the third surface may be a reference plane, the bottom surface may include an inclined portion inclined so as to come closer to the reference plane as going toward the first end part in a breaker region.

Drilling tool systems including a drilling body and a drilling inserts are disclosed. The drilling inserts include four indexable cutting edges. The four cutting edges may each comprise a plurality of cutting edge segments. The plurality of cutting edge segments are provided at distinct angles with respect to a reference plane of the drilling insert to provide effective chip breaking and a stronger cutting edge at the drilling insert corners. Furthermore, the side surfaces of the drilling inserts allow the drilling insert to be more stably supported in a pocket of the drilling body. The drilling inserts may be used in a central pocket of a drilling body.

A cutting insert may include a first surface and a second surface. The first surface may include a first side, a first corner, a second corner, and a breaker part. The breaker part may include a first segment, a second segment, and a third segment. The first segment may be an inclined surface inclined so as to approach the second surface as going away from the first side. The third segment may be an inclined surface inclined so as to separate from the second surface as going away from the second segment. In a front view of the first surface, a maximum value at a side of the second corner may be greater than a maximum value at a side of the first corner in a distance from the first side to a top portion of the third segment on an orthogonal line with respect to the first side.

A cemented carbide includes a plurality of tungsten carbide particles, and a binder phase including Co. The binder phase further includes Cr. A region in a cross section of the cemented carbide where a distance X between surfaces of the tungsten carbide particles adjacent to each other having an opposing surface length L of 100 nm or more is 5 nm or less is a WC/WC region. A peak value of atomic percentage of Cr obtained by an elemental analysis in a transverse direction from one tungsten carbide particle to the other tungsten carbide particle in the WC/WC region is a Cr value, and a peak value of atomic percentage of Co thus obtained is a Co value. A ratio of the Cr value and the Co value (Cr value/Co value) is a Cr/Co ratio, and the Cr/Co ratio is larger than 1. A cutting tool includes the cemented carbide.