Home / Precision Gear Racks / 1.1.2 Conversion / hardness / strength

Conversion / hardness / strength

Conversion / hardness / strength

Module and pitch conversion

Converting a module m into a pitch p (straight toothed) and transverse pitch ps for helical tooth racks.

Module m 2 3 4 5 6 8 10 12 16 20
Pitch p (mm) 6.28 9.42 12.57 15.71 18.85 25.13 31.42 37.70 50.27 62.83
Transverse pitch ps1) (mm) 6.67 10.00 13.33 16.67 20.00 26.67 33.33 40.00 53.33 66.67

1) where β = 19°31'42"

Converting pitch into a module

Pitch p (mm) 5.00 7.50 10.00 12.50 15.00 20.00
Module m 1.59 2.39 3.18 3.98 4.77 6.37

Formulae

  • p = Pitch (mm)
  • ps = Transverse pitch (mm)
  • m = Module
  • β = Helix angle
  • p = m × π (straight toothed)
  • p = m × π / cos β (helical toothed)

Hardness and strength

Condition of teeth Material Tensile strength Rm (N/mm²) Hardness HRc Hardness HV1
soft C45 ~650 - -
tempered 42CrMo4+QT max. 1000 - -
induction hardened C45 - 55…60 -
42CrMo4+QT - 59±3 -
case hardened 16MnCr5 - 58+3 -
nitrided 42CrMo4+QT, 16MnCr5 - - 550…700
through hardened X90CrMoV18 - 56±2 -

Diagram

Gear rack hardness and strength diagram
ESC