Rolling-Element Bearing Defects Missing at The Calculated Frequency?

Rolling-element bearings are critical components in many industrial applications, including pumps, compressors, and turbines. They are designed to support the rotating shaft and provide efficient, low-friction transmission of power. However, due to the harsh operating conditions and the nature of the rolling contact, bearings are prone to failure.

The frequency spectra of a healthy rolling-element bearing typically exhibit a series of harmonics of the fundamental rotational frequency, known as the bearing defect frequencies. The defect frequencies are related to the geometry and kinematics of the rolling elements and raceways, and they depend on the number of rolling elements, their size and spacing, and the speed and load of the bearing.

However, rolling-element bearing defect frequencies may not always be constant. In other words, they do not always show up at the calculated bearing defect frequencies. Why? This can be attributed to several possible factors:

• Manufacturing imperfections
• Shaft rotating speed that may be changed
• The actual application of the bearing on the shaft (load directions)
• Bearing stage of wear (this reason will make the frequencies continuously change; as the stage of wear changes, the frequencies change as well)

This blog post was written in conjunction with Aly Attia, MDI