Tap - Definitions
Naming the geometries
Explanation of symbols
d1 = Thread diameter
d2 = Shank diameter
d3 = Chamfer diameter
d4 = Neck diameter
d5 = Recessed square diameter
d6 = Neck diameter
d7 = Web diameter
l1 = Total length
l2 = Thread length
l3 = Useful length
l4 = Chamfer lead length
l5 = Square length
l6 = Flute length
□ = square dimension
Z = Number of flutes
v = Back taper (axial relief)
xr = Chamfer angle
Nb = Width of flute
m = Width of land
ha = Chamfer relief
hf = Relief on flanks
hr = Chamfer relief
αp = Relief angle
γp = Rake angle
Centerings
Manufacturing - construction dimensions
Tap flutes
Form A, C, E
- straight-fluted
- for through and blind holes
The flutes can hold a part of the chips. Chips get only partically removed in cutting direction. For this reason it is not recommended to use the tap for deep holes.
Form B
- straight-fluted with spiral point
- for through holes
Due to the spiral point the chips are getting removed tightly rolled in cutting direction and prevents chip-packing. Coolant-lubricant can flow freely.
Form C, D
- 8 - 15° left twisted spiral flutes
- for through holes
Due to the left-hand spiral flutes the rake angle remains constant and ensure stable chamfer teeth to produce threads in high-strength materials. The left-hand spiral flutes forces the chips to remove ahead of the tap.
Form C, E
- 10 - 15° right-hand spiral flutes
- for blind holes
Especially suitable for automatic lathes and multi-spindle machines. Due to the chip removal against the cutting direction a secured tapping process is assured in hard conditions, even for threads with cross holes.
Form C, E
- 35 - 50° right-hand spiral flutes
- for blind holes
Due to the high spiral flutes, the chips can be removed securely also in long-chipping and deep blind holes.
