Important formulas

Cutting speed and rotational speed

v = (D・π・n) : (π)

v = (v・1000) : (D・π)

n = Machine rotation speed (r/min)
v = Cutting speed (m/min)
D = Nominal diameter (mm)

Calculation of the core hole Ø

d₄ = D - P*

D = Nominal diameter (mm)
P = Pitch

* Does not apply to TR / Rd or chonical threads

Oversize on the tap for a given coating thickness

h = 2・(a : sin α)

a = Layer thickness
α = 1/2 flank angle

sin 30° = 0,5
sin 27,5° = 0,461
sin 15° = 0,259

Calculation of oversize corresponding to the layer thickness

a_e= (P²・0,5) : (z・l₄)

P = Steigung
z = Nutenzahl
l₄ = Anschnittlänge

Torques and power range

M_D= (k_c・h²・d₁) : (8000) Nm

P = (M_D・n) : (9500) kW

P_m = (P) : (η_M) kW

kc = Cuting Force (Nmm₂) (acc. to able)
h = Thread pitch
d₁ = Nominal diameter (m)
n = Rotation speed (rpm)
P_m = Required machine drive power
η_M= Machine efficiency

Material	R_m/UTS (N/mm²)	K_c-Value (N/mm²)
Unalloyed construction metal	-700	2300
Free cutting steel	-700	2300
Structural steel	500–950	2500
Medium strength tempered steel	500–950	2600
Nitrided tempered steel	950–1400	3600
Tool steel	950–1400	3600
Stainless and acid resistant steel, austenitic	500–950	3200
Aluminium alloys, long chipping	-550	800
Copper alloys, long-chipping	300–700	1100
Grey cast iron	100–400 (120–260 HB)	1250
Alloy grey cast iron	150–250 (160–230 HB)	1600
Malleable cast iron	350–700 (150–280 HB)	1100
Aluminium alloys, short-chipping	-400	680
Copper alloys, short-chipping	-500	720

Conversion inch to mm

1 Zoll = 25,400 mm

> e.g. pitch of 28 TPI = 0,90 mm