HELI-COIL spiral point taps have been designed primarily for the machine tapping of through holes. A spiral point is ground into the lead threads at an angle to the tap axis. This produces a tap with initial left hand flutes having a progressive cutting rake towards the point of the tap.
The swarf produced by this type of tap is pushed ahead of the tap and falls free as it emerges through the hole, thus eliminating the hazards caused by chips accumulating in the flutes during cutting. This type of tap, due to its improved cutting action, is suited to the tapping of precise deep holes in a single pass at very high peripheral speeds.
Spiral Flute Taps
HELI-COIL spiral flute taps have helical flutes that are ground in the same direction as the thread. This feature directs the swarf back out of the hole and makes this design of tap appropriate for the machining of blind holes particularly in materials that produce a continuous chip.
Because they are designed for tapping of blind holes they are manufactured with a bottoming chamfer lead.