Electroless plating properties
Coating thickness of Electroless Nickel Plating
Thickness Uniformity
NIPLATE® coatings offer a consistent uniform thickness over the entire surface of the workpiece, regardless of its geometry. Unlike electro-deposited coatings such as chrome plating, NIPLATE® coatings do not exhibit the "edge effect," which causes increased thickness on the edges of the substrate. This uniformity of thickness eliminates the need for subsequent additional machining on precision mechanical parts.
Hole isolation and additional post-treatment machining
Given the uniformity of thickness over the entire component, precision mechanical parts can be coated without the need for subsequent additional machining. Parts can be machined factoring in deviations due to the coating's machining allowance and fully coated, falling within even tight tolerances.
In the case of extremely tight tolerances, hole isolation can be carried out if necessary. Since the isolation operation is expensive, it is recommended to include isolation only in cases where tolerances cannot be met by calculating deviations and tolerances in advance.
For assistance in determining pre-treatment machining dimensions, you can use our pre-treatment dimensional tolerance calculator.
Selecting the Thickness
The coating thickness is chosen according to the required resistance to corrosion or wear. It usually ranges from a minimum of 3–5 µm to a maximum of 50–70 µm. The thickness tolerance is minimal, generally ± 10% of the nominal thickness, with a minimum of ± 2 µm. The standard tolerances are as follows:
| Thickness | Tolerance |
|---|---|
| 2–20 µm | ± 2 µm |
| 21–30 µm | ± 3 µm |
| 31–40 µm | ± 4 µm |
| 41–50 µm | ± 5 µm |
| 51–60 µm | ± 6 µm |
Recommended nickel plating thicknesses for corrosion resistance
Choosing a thickness is not always simple and straightforward, partly because the applications of nickel-plated parts are so varied. Sometimes only field testing can define the correct thickness.
The following table shows approximate values of electroless nickel plating thickness depending on the operating conditions.
| Operating conditions | Description | Coating thickness on iron and aluminum alloys | Coating thickness on copper alloys |
|---|---|---|---|
| 1 – Light | Indoor use in a warm, dry atmosphere | 8±2 µm | 5±2 µm |
| 2 – Moderate | Indoor environment where condensation may occur. Indoor industrial environments in dry conditions. | 15±2 µm | 8±2 µm |
| 3 – Heavy | Outdoor use with frequent wetting by rain, moisture, or water. | 30±3 µm | 15±2 µm |
| 4 – Extremely heavy | Outdoor use in a maritime environment and aggressive environmental conditions with frequent wetting by rain, moisture, or water containing pH-neutral or slightly alkaline salts. | 50±5 µm | 20±2 µm |
PRACTICAL RECOMMENDATIONS
- Our technical department is at your disposal to help determine the correct nickel plating thickness, taking all the relevant factors into consideration.
- Machining should include the thickness of the coating as a machining allowance. For example, a thickness of 10 µm shrinks holes by 20 µm or 0.02 mm.
- For metric threads, factor in a diametric deviation equal to 4 times the treatment thickness during machining.
- Use the pre-treatment dimensional tolerance calculator to determine machining dimensions so that final dimensions can be met.