Coatings applied to mechanical parts change the dimensions depending on the thickness and type of treatment performed.
With the following calculator, it is possible to calculate the pre-treatment machining dimensional tolerances that must be met to obtain the correct tolerance of the finished part after surface treatment.
Formulas for calculating tolerances
Electroless nickel plating
As for the electroless nickel plating, the nickel layer thickness is all excess metal. The dimensions should therefore be recalculated considering a diametral increment equal to twice the thickness.
SHAFTTolerance+machining = Tolerance+final – 2 × Thicknessmax
Tolerance–machining = Tolerance–final – 2 × Thicknessmin
Tolerance+machining = Tolerance+final + 2 × Thicknessmin
Tolerance–machining = Tolerance–final + 2 × Thicknessmax
Aluminum natural anodizing
On the other hand natural anodizing, treatment grows 30% outward and 70% inward on the surface. The dimensions should then be recalculated considering an increment diametral equal to 0.6 times the thickness.
SHAFTTolerance+machining = Tolerance+final – 0,6 × Thicknessmax
Tolerance–machining = Tolerance–final – 0,6 × Thicknessmin
Tolerance+machining = Tolerance+final + 0,6 × Thicknessmin
Tolerance–machining = Tolerance–final + 0,6 × Thicknessmax
Aluminum hard anodizing
For hard anodizing, on the other hand, the treatment grows 50% outward and 50% inward on the surface. The dimensions should then be recalculated considering a diametral increase equal to thickness.
SHAFTTolerance+machining = Tolerance+final – Thicknessmax
Tolerance–machining = Tolerance–final – Thicknessmin
Tolerance+machining = Tolerance+final + Thicknessmin
Tolerance–machining = Tolerance–final + Thicknessmax
