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What is pitting corrosion and how can it be prevented?

2018-08-14

Definition of pitting corrosion

Pitting or pitting corrosion is a type of localized bearing damage that can initiate corrosion cracking and corrosion fatigue. Externally, pitting looks like depressions (ulcers or cavities) on the surface of the metal.

Despite the fact that outwardly the damage does not look significant, it is dangerous for the bearing, because as the number of such damages on the raceways increases, the working surfaces of balls or rollers become rough, the bearing begins to make noise and overheat. And this already reduces the service life of the bearing. Therefore, the presence of such a defect must be carefully monitored and, if possible, to prevent its occurrence and spread.

Causes of pitting corrosion:

The presence of solid particles in the lubricant (debris or contamination);

Exposure to atmospheric humidity;

Lack of or insufficient lubrication.

Poor lubricant quality (e.g. low viscosity)

How can I prevent pitting corrosion?

Select the correct bearing type and bearing design (quality seals, etc.)

Ensure the integrity of the bearing seals during operation.

Carefully filter the lubricating oil.

Use a grease which is suitable for the temperature and speed conditions of operation.