SAE AMS 2400
Plating, Cadmium
Specifies electrodeposited cadmium plating on metal parts, including thickness classes and supplementary treatment.
What SAE AMS 2400 specifies
SAE AMS 2400 controls aerospace cadmium electroplating for corrosion resistance, lubricity, and galvanic compatibility with aluminum. Class 1, 2, and 3 minimum thicknesses are 0.0005, 0.0003, and 0.0002 in (12.7, 7.6, and 5.1 µm). Type I is as-plated cadmium; Type II receives a supplementary chromate treatment. High-strength steel requires tightly controlled stress relief and prompt post-plate hydrogen-embrittlement relief. Because cadmium and hexavalent-chromium treatments are regulated, buyers should use this finish only where its aerospace function and customer authorization justify it, and state type, class, significant surfaces, masking, and bake requirements.
SAE AMS 2400 types and classes
Every designation the document defines, with the thickness it requires and the tests it imposes.
| Designation | Meaning | Thickness | Requirement / test |
|---|---|---|---|
Class 1 | Thickest standard cadmium class. | ≥ 13 µm ≥ 0.5 mil | Thickness, adhesion, corrosion, and embrittlement controls. |
Class 2 | General aerospace cadmium thickness. | ≥ 8 µm ≥ 0.3 mil | Thickness, adhesion, corrosion, and embrittlement controls. |
Class 3 | Thin cadmium for dimensionally restricted surfaces. | ≥ 5 µm ≥ 0.2 mil | Thickness, adhesion, corrosion, and embrittlement controls. |
Type I | As-plated cadmium without supplementary conversion treatment. | — | Appearance and applicable corrosion test. |
Type II | Cadmium with supplementary chromate treatment. | — | Appearance and applicable salt-spray test. |
Tests and the drawing call-out
Tests the document imposes
- Coating thickness
- Adhesion
- Corrosion resistance
- Hydrogen-embrittlement relief and periodic embrittlement test
- Visual examination
How to cite it
Drawing call-out
CADMIUM PLATE PER SAE AMS 2400, TYPE <I|II>, CLASS <1|2|3>, <COLOR>, <EMBRITTLEMENT-RELIEF BAKE>Angle brackets mark the choices the drawing must make; every finish page shows a completed example.
Finishes specified to SAE AMS 2400
SAE AMS 2400 — frequently asked
What are the AMS 2400 thickness classes?
Class 1 is at least 12.7 µm, Class 2 at least 7.6 µm, and Class 3 at least 5.1 µm. Select the class from corrosion and dimensional needs.
What is the difference between Type I and Type II?
Type I is as-plated cadmium. Type II adds a chromate conversion treatment for improved corrosion performance.
Can cadmium be used on any commercial part?
Cadmium is toxic and heavily regulated, so it should be reserved for authorized aerospace or similarly critical uses. Zinc-nickel is often evaluated as an alternative.
SAE AMS 2400 is copyrighted by SAE International. This page explains the document so a drawing can be read; it does not reproduce the standard. Purchase the current edition from the publisher. Official source ↗