A thread forming tap includes a partial thread. The partial thread is provided, in the axis direction view, with a protrusion formed so as to protrude in the radial direction and a clearance section formed so as to have a smaller diameter than the protrusion, and as a result of the foregoing, if a thread forming tap rotates in a state where the inner circumferential surface of a pilot hole and the partial thread come into contact, the protrusion of the partial thread can be caused to engage with the inner circumferential surface of the pilot hole. Due to this configuration, rubbing in a state where the partial thread is pressed against the inner circumferential surface of the pilot hole can be suppressed, and as a result, chipping of the partial thread can be prevented.

A thread forming tap includes a partial thread. The partial thread is provided, in the axis direction view, with a protrusion formed so as to protrude in the radial direction and a clearance section formed so as to have a smaller diameter than the protrusion, and as a result of the foregoing, if a thread forming tap rotates in a state where the inner circumferential surface of a pilot hole and the partial thread come into contact, the protrusion of the partial thread can be caused to engage with the inner circumferential surface of the pilot hole. Due to this configuration, rubbing in a state where the partial thread is pressed against the inner circumferential surface of the pilot hole can be suppressed, and as a result, chipping of the partial thread can be prevented.

A thread cutting tap and a method of treating the thread cutting tap, which includes a thread cutting portion including a plurality of cutting lands, is provided. Each cutting land has one or more thread cutting teeth in the chamfered section. Each thread cutting tooth includes a primary cutting edge. The method includes immersing at least the thread cutting portion in a bed of granules and effectuating relative movement between the thread cutting portion and the granules for generating an edge rounding of a first magnitude at the primary cutting edge of each tooth, and then exposing a subset of the thread cutting teeth to a dynamic plastic deformation treatment. The subset includes all the thread cutting teeth in the chamfered section, so as to generate an edge rounding of a second magnitude, greater than the first magnitude, at the primary cutting edge of each tooth in the subset.

A thread cutting tap and a method of treating the thread cutting tap, which includes a thread cutting portion including a plurality of cutting lands, is provided. Each cutting land has one or more thread cutting teeth in the chamfered section. Each thread cutting tooth includes a primary cutting edge. The method includes immersing at least the thread cutting portion in a bed of granules and effectuating relative movement between the thread cutting portion and the granules for generating an edge rounding of a first magnitude at the primary cutting edge of each tooth, and then exposing a subset of the thread cutting teeth to a dynamic plastic deformation treatment. The subset includes all the thread cutting teeth in the chamfered section, so as to generate an edge rounding of a second magnitude, greater than the first magnitude, at the primary cutting edge of each tooth in the subset.