Cutting dies tolerances classes

Metric ISO thread acc. DIN 13 - coarse and fine thread

4h = tolerance class "fine"

6h = tolerance class "middle", for small diameters (up to M 1.4)

6g = tolerance class "middle" - standard

6e = undersize tolerance; for bolts that receive a surface threatment or a galvanizing (layer thickness up to 8 µm). Cutting dies with 6e tolerance are cutting about 0,03 mm smaller than normal cutting dies with 6g tolerance.

8e = Untermaß-Toleranz; für Bolzen, die eine starke Beschichtung erhalten (Schichtstärke ca. 16 - 18 µm)

Unified thread UNC, UNF, UNEF, UNS, UN, UNJC, UNJF, etc.

3A = tolerance "fine"

2A = standard tolerance "middle"

1A = tolerance "coarse"

Whitworth pipe thread G (BSP) acc. to DIN-ISO 228

A = Standard tolerance "middle"
B = Tolerance "coarse"

Die nomenclature

technical drawing of a die with a spiral entry

Explanation of symbols

D = Outside diameter
E = thickness
a = width of tooth
c = width of notch

b = diameter of hole for fixing screw
α = rake angle
β = chamfer angle
γ = spiral angle

Preparation of workpiece:

  • concentrical chamfer - ease entry of cutting
  • workpiece diameter must be less than the nominal diameter


  • Standard chamfer (length, see at the item)
  • Spiral entry: free flow of chips ahead of the die and a reducing of cutting torque. This resulsts in an improved surface finish on the cut threads and longer die life
  • 70° (short chamfer) - chamfer length: 1,25 pitch = 70°