bearings life

The basis of the rating life calculation in accordance with ISO 281 is Lundberg and Palmgren's fatigue theory which always gives a final rating life.

However, modern, high quality bearings can exceed by a considerable margin the values calculated for the basic rating life under favourable operating conditions. Ioannides and Harris have developed a further model of fatigue in rolling contact that expands on the Lundberg/Palmgren theory and gives a better description of the performance capability of modern bearings.

The method “Expanded calculation of the adjusted rating life” takes account of the following influences:

  • the bearing load
  • the fatigue limit of the material
  • the extent to which the surfaces are separated by the lubricant
  • the cleanliness in the lubrication gap
  • additives in the lubricant
  • the internal load distribution and frictional conditions in the bearing.

The influencing factors, especially those relating to contamination, are extremely complex. A great deal of experience is essential for an accurate assessment. As a result the Engineering Service of Schaeffler Group Industrial should be consulted for further advice.

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