"Nickel plating" refers to two distinct processes: electroless and electroplated. They behave differently, and the right choice depends on your part's geometry and how uniform the coating must be.
Side by side
| Electroless nickel (ENP) | Electroplated nickel | |
|---|---|---|
| How it's deposited | Chemical (autocatalytic) bath | Electric current |
| Thickness uniformity | Even everywhere — bores, threads, recesses | Heavy on edges, thin in recesses/bores |
| Typical thickness | 8–25 µm | ~5–40 µm (uneven) |
| Hardness | High (higher after a high-temp bake) | Moderate |
| Corrosion | High | Moderate–high |
| Look | Uniform satin | Bright, cosmetic |
| Cost | $$$ | $$ |
| Best for | Complex parts, deep features, hardness, all-over thickness | Simple shapes, bright look, lower cost |
Electroless (ENP)
Because the metal is deposited by a chemical reaction rather than by electric current, it builds the same thickness on every surface — the inside of a deep bore is coated as evenly as an outside edge. The deposit is a hard, wear-resistant nickel-phosphorus alloy, and a high-temperature bake (~340–400 °C) hardens it further still — though on age-hardened aluminium like 6061/7075 the bake is kept low to protect the temper, so there it mainly improves adhesion and relieves stress. That makes electroless the right choice for complex geometry and for any part where the plated thickness has to stay in tolerance everywhere.
Electroplated
Electroplating is faster, lower in cost, and produces a bright, cosmetic finish. The limitation is inherent to the process: the electric current concentrates on edges and corners, so the coating builds up thick there and remains thin inside bores and recesses. It suits simple shapes where appearance or cost is the priority.
Plating aluminium
Aluminium grades like 6061 and 7075 won't accept nickel directly — they need a pre-treatment called a zincate step that prepares the surface for either process. We confirm the exact spec at quoting.
Three quick mistakes
- Expecting plating to smooth a rough surface — it mirrors what's underneath, so finish the part first.
- Not stating a thickness or a spec — for electroless nickel, call out ASTM B733.
- Forgetting that the coating adds thickness — it eats into tight bores and close fits.
Quick rule
Complex geometry, uniform coverage, or hardness → electroless. Simple shape, a bright look, or lower cost → electroplated.
