Pre-treatment dimensional tolerances calculator

Published on 20/10/2020 by Giacomo Bordiga

Cartouche technical drawing showing surface treatment

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.

Final dimension, after surface treatment


Surface treatment



Machining dimensions, before 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.

SHAFT

Tolerance+machining = Tolerance+final – 2 × Thicknessmax
Tolerancemachining = Tolerancefinal – 2 × Thicknessmin

HOLE

Tolerance+machining = Tolerance+final + 2 × Thicknessmin
Tolerancemachining = Tolerancefinal + 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.

SHAFT

Tolerance+machining = Tolerance+final – 0,6 × Thicknessmax
Tolerancemachining = Tolerancefinal – 0,6 × Thicknessmin

HOLE

Tolerance+machining = Tolerance+final + 0,6 × Thicknessmin
Tolerancemachining = Tolerancefinal + 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.

SHAFT

Tolerance+machining = Tolerance+final – Thicknessmax
Tolerancemachining = Tolerancefinal – Thicknessmin

HOLE

Tolerance+machining = Tolerance+final + Thicknessmin
Tolerancemachining = Tolerancefinal + Thicknessmax

Fotografia profilo Giacomo Bordiga
Ing. Giacomo Bordiga
Operational Management
Linkedin giacomo@microncoatings.it +39 3282811559 Whatsapp