A cutting head rotatable about a head axis has a cap portion and a rigid mounting protuberance joined to the cap portion. The cap portion has exactly four cutting portions circumferentially alternating with four head flutes and a head base surface facing in an axially rearward direction. The mounting protuberance extends axially rearwardly from the head base surface and has exactly two circumferentially spaced apart convex clamping surfaces. In a cross-section taken in a first horizontal plane perpendicular to the head axis and intersecting the mounting protuberance, only the two clamping surfaces are circumscribed by an imaginary first circle having a first diameter and a center coincident with the head axis. A rotary cutting tool has an elongated tool shank with a head receiving pocket at a forward end thereof and the cutting head of the type described above releasably secured to the head receiving pocket.

An insert includes a cutting portion and a shaft portion. The cutting portion includes: a cutting edge that is located on a side of a first end; an end surface that is located on a side of the side of a second end; and a first through hole extending from the end surface toward the first end. The first through hole includes: a first opening that is located on the side of the first end; and a second opening located on the side of the second end. The first opening is positioned in the rear of the second opening in a rotational direction of the rotational axis.

An insert includes a main body extending from a first end toward a second end. The main body includes a cutting edge, a rake face, and a flute. In the rake face, a second rake angle of a second surface region positioned closer to the second end than a first surface region connected to the cutting edge is smaller than a first rake angle of the first surface region. A third rake angle of a third surface region is smaller than the second rake angle, the third surface region being adjacent to the flute rearward in a rotational direction and on an outer peripheral side of the main body.

A cutting tool assembly includes a tool shank having a coupling opening, and an insert holder having an insert body to which an insert is coupled and detachably attached. A coupling protrusion protrudes from one surface of the insert body and is detachably coupled to the tool shank. Located on the coupling protrusion are a tapered contact portion which comes into contact with the coupling opening and provides a fixing force to fix the insert holder to the tool shank, and a contact surface at a rear end of the tapered contact portion which couples to a fastening member.

A cutting head rotatable about a head axis has a cap portion and a rigid mounting protuberance joined to the cap portion. The cap portion has exactly four cutting portions circumferentially alternating with four head flutes and a head base surface facing in an axially rearward direction. The mounting protuberance extends axially rearwardly from the head base surface and has exactly two circumferentially spaced apart convex clamping surfaces. In a cross-section taken in a first horizontal plane perpendicular to the head axis and intersecting the mounting protuberance, only the two clamping surfaces are circumscribed by an imaginary first circle having a first diameter and a center coincident with the head axis. A rotary cutting tool has an elongated tool shank with a head receiving pocket at a forward end thereof and the cutting head of the type described above releasably secured to the head receiving pocket.

A cutting insert for a rotary drill tool and drill tool assembly in which an insert and a support body are coupled via a plurality of axial support surfaces. The support surfaces include a first declined orientation in the axial direction and a second declined orientation in the circumferential direction, so as to manage and control transmission of loading forces at the region of mounting the insert at the support body.

A cutting tool assembly includes a tool shank having a coupling opening, and an insert holder having an insert body to which an insert is coupled and detachably attached. A coupling protrusion protrudes from one surface of the insert body and is detachably coupled to the tool shank. Located on the coupling protrusion are a tapered contact portion which comes into contact with the coupling opening and provides a fixing force to fix the insert holder to the tool shank, and a contact surface at a rear end of the tapered contact portion which couples to a fastening member.

A cutting insert for a rotary drill tool and drill tool assembly in which an insert and a support body are coupled axially via a complementary shaped projection extending radially outward from the insert and received with a recess indented at a radially inward facing surface of the support body.

A cutting insert for a rotary drill tool and drill tool assembly in which an insert and a support body are coupled via a plurality of axial support surfaces. The support surfaces include a first declined orientation in the axial direction and a second declined orientation in the circumferential direction, so as to manage and control transmission of loading forces at the region of mounting the insert at the support body.

A cutting tool includes a base body and a cutting head at least partially disposed within a modular pocket of the base body. The modular pocket is formed by at least one wall section removably attached to the base body. In one variation, a non-removable portion of the base body also forms part of the modular pocket. In another variation, the modular pocket is formed by two removable wall sections on opposite sides of the modular pocket. In yet another variation, the removable wall sections include a clamping portion to exert a downward force on the cutting head to enable mounting the cutting head in the modular pocket using an interference fit.