Why is cadmium plating used to protect precision metal parts?

Cadmium plating is used to protect precision metal parts primarily because it provides excellent corrosion resistance, particularly in marine atmospheres, and is highly resistant to attack by alkali.1

From a technical standpoint, cadmium deposits offer several advantages for precision applications:
* Uniformity: Cadmium plating tends to be more smooth and uniform than electro-zinc coatings, and it features a smaller grain size.1
* Efficiency: Because the deposits are uniform, effective protection can be achieved with thin coatings, which is beneficial for maintaining the tolerances of precision parts.1
* Durability: While cadmium is physically similar to zinc, it is denser and softer, providing a reliable protective barrier for alloys such as steel, iron, copper, and brass.1

Despite these functional benefits, it is important to note that cadmium is a toxic substance. Inhalation of its dust or vapors is hazardous, and ingestion—such as from food or drink prepared in cadmium-lined vessels—can cause severe cadmium poisoning.12