29. Fan’s bearing lubrication

Statistics performed by manufacturers are showing that early malfunctions are essentially due to the following reasons:

  • Inappropriate mounting: 16%
  • Incorrect lubrication: 36%
  • Pollution: bearing ways contamination: 14%
  • Fatigue: overload – incorrect or insufficient maintenance: 34%

The bearings installed on the industrial fans are operating often at high speed and with average low radial loads.
Despite the wrong idea that the main goal of the bearing lubrication is to restrain the frictions, they are first used to create at the pieces surface very strong adhesive film, forbidding any possible
metal/metal contact to avoid galling.

An excess of lubrication is generally creating an increase of frictions and therefor a heating that might be injurious for the component length-life. We use mainly grease and oil eventually loaded with solid lubricant as for example graphite or Molybdenum disulfide.

Grease lubrication

The grease is chosen as lubricant for bearing in the case of normal speed and temperature operation. The grease own several advantages in regards with oil: it allows a non-sophisticated installation, therefor less expensive, with a better adherence and ensure a protection against humidity and impurities.

Oil lubrication

Oil is the most appropriate lubricant when the speed and/or operating conditions are not allowing the use of grease or when the heat should be removed from the bearing.
The grease is the most easy use lubricant and do not requires complex sealing systems. For that reason, this is the lubricant type the most used for bearings.