Electroplating: Zinc, Nickel, Chrome & Specs
A sacrificial corrosion layer with real dimensional cost — the plating thickness belongs in the drawing, not in an assumption.
Request a quoteWhat actually happens to the part
The part is made the cathode in an electrolytic cell. Metal ions in the solution deposit as a layer on the surface, then a conversion or passivation layer is added for corrosion resistance.
| Parameter | Value |
|---|---|
| Zinc (blue/silver) | Economical sacrificial protection |
| Zinc-nickel | Longer life than plain zinc |
| Nickel | Hardness and wear resistance, can be brittle |
| Chrome | Hard, wear resistant, expensive |
| Thickness | Typically 5–25 µm |
| Passivation layer | White or black chromate over zinc |
| Surface roughness | Ra 0.2–0.8 µm, usually improves on the raw surface |
| Typical lead time added | Add 4–7 working days |
What this finish does to your tolerances
This is where most prototype surprises come from. A finish is not decoration — it moves dimensions, and the drawing has to account for it.
This is the finish to watch. A 25 µm plating adds 12.5 µm per surface, so a bore shrinks by 25 µm and a shaft grows by 25 µm. Every plated mating dimension has to be called out, and threads need masking or a class allowance.
Suitable for
- Steel
- Aluminium (with a strike layer)
- Brass
- Copper
Not suitable for
- PEEK, POM and other plastics — plating needs a metallic underlayer
- Precision fits that were not called out on the drawing
- Food-contact surfaces without a compliant finish specification
What engineers ask about Electroplating: Zinc, Nickel, Chrome & Specs
Why did my plated part not fit?
Almost always plating thickness that was not accounted for in the drawing. Plated holes are smaller and shafts are larger. We ask for the plating callout before quoting, and we will flag any dimension that the plating will move.
Is chrome plating the same as chrome electroplating?
Hard chrome is an industrial electroplate and contains hexavalent chromium, which carries regulatory restrictions in some regions. Decorative chrome on consumer parts is a different specification entirely.