High spiral flutes of 45° or greater – Ideal for ductile materials like aluminium and copper. When used in other materials, they often cause chips to nest because the spiral is too fast and the chip area is too tight for chips to form properly.
Spiral flutes 38° – 42° – Suitable for medium to high carbon steels or free machining.
Stainless steels are machined. They produce a chip that is sufficiently tight to allow for easy evacuation. Pitch relief is available on larger taps to help in cutting.
Spiral flutes 25° – 35° – For free machining, low or leaded steels, and free machining bronzes or brasses. Spiral flute taps used in brass and strong bronzes typically work poorly because the little fractured chip does not flow smoothly up the spiral flute.
Spiral flutes 5° – 20° – A slower spiral is preferred for stronger materials such as stainless steel, titanium, or high nickel alloys. This permits the chips to be drawn somewhat upward while not compromising the cutting edge as much as higher spirals would.