There is provided a drill insert for drilling metallic or other materials, comprising a drill insert body with first and second lands at the outside diameter of the body that interface with the wall of a drilled hole. There is provided a coolant relief arrangement at the outside diameter of the drill insert by a plurality of coolant supply channels extending between the leading edge and trailing edge of the interface, to provide coolant relief to the outside diameter of the drill insert at the interface with the drilled hole. The drill inserts of the invention provide reduced friction and heat generation while maintaining high stability, and operate to prevent accumulation of materials on surfaces of the drill inserts at the outside diameter of the drill insert. This enables higher penetration rates and operating speeds while maintaining integrity of the drill inserts.

A cutting tool has a rake face and a flank face. The flank face is provided with a coolant supply hole. A ridgeline between the rake face and the flank face forms a cutting edge. An outer shape of the coolant supply hole in a cross section orthogonal to an axis includes a first portion facing the cutting edge, and a second portion opposite to the cutting edge when viewed from the first portion. The first portion has a concave portion extending toward the second portion. The concave portion is defined by a first side portion and a second side portion facing each other, and a bottom continuous with both the first side portion and the second side portion. In the cross section, an angle formed by a tangent of the first side portion and a tangent of the second side portion is not more than 160°.

In a rotating tool with a coolant hole, a coolant hole extending to a front side in the direction of an axis opening to a tip flank face of a drill main body that is rotated around the axis. In a cross section orthogonal to the axis, the coolant hole is provided with a first concavely curved portion located on an inner peripheral side of the drill main body and formed in a concavely curved shape recessed to the inner peripheral side, a second concavely curved portion located on an outer peripheral side of the drill main body and formed in a concavely curved shape recessed to the outer peripheral side with a larger curvature radius than the first concavely curved portion, two third concavely curved portions having a center of a curvature radius located inside the coolant hole with a smaller curvature radius than the second concavely curved portion.

A cutting tool body includes a first member and a second member, both having a substantially cylindrical shape, and arranged such that a tool body central axis coincides with a central axis of each of the first and the second members. The first member has a tool characteristic of a first magnitude and the second member has the tool characteristic of a second magnitude, different from the first magnitude. The cutting tool body includes a transition member arranged between the first and second members and connected at a first end to the first member and at a second end to the second member. The tool characteristic in the transition member is of the first magnitude at the first end and of the second magnitude at the second end. The transition member has a transition region between the first and the second ends in which the tool characteristic transforms from the first magnitude to the second magnitude.

A cutting tool body includes a first member and a second member, both having a substantially cylindrical shape, and arranged such that a tool body central axis coincides with a central axis of each of the first and the second members. The first member has a tool characteristic of a first magnitude and the second member has the tool characteristic of a second magnitude, different from the first magnitude. The cutting tool body includes a transition member arranged between the first and second members and connected at a first end to the first member and at a second end to the second member. The tool characteristic in the transition member is of the first magnitude at the first end and of the second magnitude at the second end. The transition member has a transition region between the first and the second ends in which the tool characteristic transforms from the first magnitude to the second magnitude.

A cutting tool has a rake face and a flank face. The flank face is provided with a coolant supply hole. A ridgeline between the rake face and the flank face forms a cutting edge. An outer shape of the coolant supply hole in a cross section orthogonal to an axis includes a first portion facing the cutting edge, and a second portion opposite to the cutting edge when viewed from the first portion. The first portion has a concave portion extending toward the second portion. The concave portion is defined by a first side portion and a second side portion facing each other, and a bottom continuous with both the first side portion and the second side portion. In the cross section, an angle formed by a tangent of the first side portion and a tangent of the second side portion is not more than 160.

A drill is provided with a flank at a leading end portion of a body. An oil hole is provided at the flank, having a fan-shaped cross-section. The fan-shaped cross-section is formed by being surrounded by a front-side inner wall surface, a rear-side inner wall surface, an outer peripheral-side inner wall surface, and an inner peripheral-side inner wall surface. Compared to a round hole, a discharge performance of cutting fluid of the oil hole is high. The rear-side inner wall surface curves in a circular arc shape toward the front in a rotation direction. Thus, the drill can secure a distance between a ridge section of the flank and the rear-side inner wall surface to be wide, can suppress stress acting on a section between the ridge section of the flank and the oil hole, and can thus increase a discharge amount of the cutting fluid and also secure a tool rigidity.

A drill body of an indexable insert drill includes at least two chip flutes separated from each other in the circumferential direction of the drill body by intermediate ribs, each chip flute and each rib extending in a helically curved path. An insert seat is located at a transition between each chip flute and a front face of the drill body. Coolant ducts are arranged in and extending along a respective one of the ribs. Each coolant duct extends in a helically curved path and has an upstream end with an inlet opening and a downstream end with an outlet opening. Each coolant duct has a cross-sectional area that varies in the axial direction of the coolant duct, such that it has a smaller cross-sectional area at its outlet opening than at its inlet opening.

A tool arrangement with a tool receptacle and a tool, with at least one fluid channel for supplying a fluid to the tool provided in the tool arrangement. In order to allow an improved supply of alternative fluids to the tool, the fluid channel has at least one throttle point for maintaining the pressure in the fluid channel upstream of the throttle point, and the throttle point is suitable for keeping the pressure on the fluid sufficiently high such that no excessive premature evaporation of the fluid takes place.

In a rotating tool with a coolant hole, a coolant hole extending to a front side in the direction of an axis opening to a tip flank face of a drill main body that is rotated around the axis. In a cross section orthogonal to the axis, the coolant hole is provided with a first concavely curved portion located on an inner peripheral side of the drill main body and formed in a concavely curved shape recessed to the inner peripheral side, a second concavely curved portion located on an outer peripheral side of the drill main body and formed in a concavely curved shape recessed to the outer peripheral side with a larger curvature radius than the first concavely curved portion, two third concavely curved portions having a center of a curvature radius located inside the coolant hole with a smaller curvature radius than the second concavely curved portion.