A cutting tool part includes a cutting portion. The cutting tool part further includes a plurality of guide pads projecting radially outwards from the cutting portion. At least the cutting portion and the plurality of guide pads are made through additive manufacturing, the plurality of guide pads being integrally formed with the cutting portion in a unitary one-piece construction. A rotary cutting tool is provided having a cutting insert releasably attached to the cutting tool part.

A drill is provided with a body having a rod shape configured to rotate about a rotational axis, a cutting edge that is located at a tip portion of the body and extends from an outer periphery of the body toward the rotational axis when viewed from the tip portion, a flank located at the tip portion and disposed along the cutting edge, a covering layer that covers at least the tip portion of the body, and one or more recessed portions disposed on the flank at positions close to the cutting edge.

A drill is provided with a body having a rod shape configured to rotate about a rotational axis, a cutting edge that is located at a tip portion of the body and extends from an outer periphery of the body toward the rotational axis when viewed from the tip portion, a flank located at the tip portion and disposed along the cutting edge, a covering layer that covers at least the tip portion of the body, and one or more recessed portions disposed on the flank at positions close to the cutting edge.

According to one implementation, a drill has at least one cutting edge. A projected shape of a passing area of a ridgeline of the at least one cutting edge when the at least one cutting edge is rotated around a tool axis becomes a line-symmetric and discontinuous line along a parabola, two parabolas, an ellipse or two ellipses. The projected shape is drawn on a projection plane parallel to the tool axis.

A drill has a body extended along a rotation axis from a first end toward a second end. The body has an outer peripheral surface, a cutting edge, a flank surface, and a flute. The cutting edge has a first cutting edge, a second cutting edge extended from the first cutting edge, and a third cutting edge extended from the second cutting edge. The flank surface has a first flank surface which is located along the first cutting edge and has a first clearance angle, a second flank surface which is located along the second cutting edge and has a second clearance angle, and a third flank surface which is located along the third cutting edge and has a third clearance angle. The second clearance angle is smaller than each of the first clearance angle and the third clearance angle.

A drill has a body extended along a rotation axis from a first end toward a second end. The body has an outer peripheral surface, a cutting edge, a flank surface, and a flute. The cutting edge has a first cutting edge, a second cutting edge extended from the first cutting edge, and a third cutting edge extended from the second cutting edge. The flank surface has a first flank surface which is located along the first cutting edge and has a first clearance angle, a second flank surface which is located along the second cutting edge and has a second clearance angle, and a third flank surface which is located along the third cutting edge and has a third clearance angle. The second clearance angle is smaller than each of the first clearance angle and the third clearance angle.

The outer peripheral surface is provided with a first margin contiguous to each of the cutting edge and the flank face, and a second margin that is located on the rear side with respect to the first margin in a rotation direction and that is separated from each of the flank face and the thinning face. An outer peripheral portion of the first margin and an outer peripheral portion of the second margin have respective back tapers having the same angle. In a direction parallel to the axial line, a distance between a front end of the first margin and a front end of the second margin is more than or equal to 3 mm and less than or equal to 5 mm.

The outer peripheral surface is provided with a first margin contiguous to each of the cutting edge and the flank face, and a second margin that is located on the rear side with respect to the first margin in a rotation direction and that is separated from each of the flank face and the thinning face. An outer peripheral portion of the first margin and an outer peripheral portion of the second margin have respective back tapers having the same angle. In a direction parallel to the axial line, a distance between a front end of the first margin and a front end of the second margin is more than or equal to 3 mm and less than or equal to 5 mm.

A drill according to an embodiment includes a bar-shaped drill body extending along a rotation axis, a cutting edge located at a front end of the drill body, and a first flute extending spirally from the cutting edge toward a rear end of the drill body. The first flute includes a first region which is located close to the front end and has a helix angle θ1, and a second region which is located closer to the rear end than the first region and has a helix angle θ2 smaller than the helix angle θ1. The second region includes an elongated protruding part along the first flute.

A drill according to an embodiment includes a bar-shaped drill body extending along a rotation axis, a cutting edge located at a front end of the drill body, and a first flute extending spirally from the cutting edge toward a rear end of the drill body. The first flute includes a first region which is located close to the front end and has a helix angle θ1, and a second region which is located closer to the rear end than the first region and has a helix angle θ2 smaller than the helix angle θ1. The second region includes an elongated protruding part along the first flute.