These taps are designed for machine tapping in ductile materials. Also known as Cold Forming Tap, Roll Forming Tap or Fluteless Tap. Emkay Tools Hi-Performance Thread Forming Taps have no flutes or cutting edges but have special roll forming lobes with circular lands and short taper leads for through or blind holes. Since the displacement of metal has to be considered, specially calculated pre-tapping drill sizes are necessary.
For tapping depths, more than twice the tap diameter, roll taps with oil grooves are recommended. These grooves provide a passage for the lubricant and also for the escape of air and oil to avoid a piston effect in blind holes.