Why do bearings rust, and how to prevent bearings from rusting?

Bearings may rust due to the presence of moisture and oxygen, which are the primary causes of rust (iron oxide) formation, as detailed below.

1. Material composition. Most bearings are made of steel, which contains iron, which tends to rust when exposed to moisture and oxygen. Bearings can also be made from other materials such as stainless steel or ceramic, which are less susceptible to rust but are still susceptible under certain conditions.

2. Moisture. Moisture or moisture is a key factor in the formation of rust. When moisture comes into contact with the bearing surface, it can penetrate microscopic defects, scratches or gaps in the protective coating on the bearing surface, thus affecting the bearing.

3. Oxygen. Oxygen in the air reacts with the iron in the bearing to form iron oxide, commonly known as rust. This reaction is accelerated in the presence of moisture.

4. Pollutants. The corrosion process is exacerbated by the presence of contaminants in the environment, such as salt, dirt or chemicals, which introduce impurities and create conditions conducive to rust.

To prevent bearings from rusting, various protective measures can be taken, including lubrication, sealing, and coating. Among them, proper lubrication can form a protective layer on the bearing surface to protect the bearing from moisture and oxygen and reduce the risk of rust. Seals and dust covers effectively protect the internal components of the bearing from external contaminants and moisture. Additionally, some bearings are coated with zinc, nickel, or other anti-corrosion coatings to provide additional protection against rust.

In addition to the above methods, stainless steel bearings can also be used directly. Stainless steel bearings can reduce the possibility of rusting because stainless steel contains chromium, which will form a passivation layer to help prevent corrosion. Controlling bearings to minimize their exposure to moisture, humidity and contaminants, if possible, will also help prevent corrosion and extend bearing life.