SPIRAL FLUTE - These taps are used to produce a thread close to the bottom of a blind hole and therefore have a very short lead. The right hand spiral cut of the flutes acts to force the swarf away from the cutting teeth to the rear of the flutes and out of the hole. They are better on materials which form long continuous stringy swarf, rather than chips. They are also better to tap a thread in a hole where there is a break in the material, e.g. another hole, as the spiral fluting helps the tap to pick up on the other side. Spiral flute taps can have slow or fast helix angles.
Advantages :
• Can be used in both blind holes & also in through holes
• Chips are pushed upwards due to spiral flute – Chip clogging avoided
• Full thread depth can be achieved and this design prevents tap breakage