Pre-treatment dimensional tolerances calculator

With the online calculator presented below, you can determine the dimensional tolerances of shafts and holes.
This tool takes into consideration the coatings applied to mechanical parts, allowing you to calculate the dimensional tolerances needed in mechanical pre-treatment machining, in order to ensure the correct tolerance of the finished piece after surface treatment.

Geometry

Enter the data related to the dimension for which you want to perform the tolerance calculation.

Surface	Shaft Hole
Diameter [mm]
Tolerance	A B C CD D E EF F G H JS J K M N P R S T U V X Y Z ZA ZB ZC a b c cd d e ef f fg g h js j k m n p r s t u v x y z za zb zc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Final dimensions

Dimensions and tolerances related to the final dimension, after any surface treatment.

Max Dimension [mm]		Center [mm]
Min Dimension [mm]

Treatment

Please input the data related to the surface treatment to be applied.

Treatment	Electroless nickel plating Anodizing Hard anodizing
Minimum thickness [µm]
Maximum thickness [µm]

Pre-treatment mechanical processing dimensions

Dimensions and tolerances related to the machining dimension, before surface treatment.

Max Dimension [mm]		Center [mm]
Min Dimension [mm]

Formulas for tolerance calculation.

Electroless Nickel Plating

Regarding the electroless nickel plating, the treatment thickness is all oversize. The dimensions will need to be recalculated considering a diametrical increase equal to twice the thickness.

SHAFT

Tolerance⁺_machining = Tolerance⁺_final – 2 × Thickness_max
Tolerance^–_machining = Tolerance^–_final – 2 × Thickness_min

HOLE

Tolerance⁺_machining = Tolerance⁺_final + 2 × Thickness_min
Tolerance^–_machining = Tolerance^–_final + 2 × Thickness_max

Aluminum Anodizing

Regarding the anodizing, the treatment increases by 30% outward and 70% inward from the surface. The dimensions will need to be recalculated considering a diametrical increase equal to 0.6 times the thickness.

SHAFT

Tolerance⁺_machining = Tolerance⁺_final – 0.6 × Thickness_max
Tolerance^–_machining = Tolerance^–_final – 0.6 × Thickness_min

HOLE

Tolerance⁺_machining = Tolerance⁺_final + 0.6 × Thickness_min
Tolerance^–_machining = Tolerance^–_final + 0.6 × Thickness_max

Aluminum Hard Anodizing

Regarding the hard anodizing, the treatment increases by 50% outward and 50% inward from the surface. The dimensions will need to be recalculated considering a diametrical increase equal to the thickness.

SHAFT

Tolerance⁺_machining = Tolerance⁺_final – Thickness_max
Tolerance^–_machining = Tolerance^–_final – Thickness_min

HOLE

Tolerance⁺_machining = Tolerance⁺_final + Thickness_min
Tolerance^–_machining = Tolerance^–_final + Thickness_max