Detection of rolling element bearing defects


Gas turbines and balance-of-plant machines use rolling element bearings, and detecting defects at an early stage is critically important to the safe and economical operation of the equipment.  This technical presentation will discuss the available measurement and vibration analysis techniques.

The discussion will open with a basic explanation of how rolling element bearings work and how defects manifest themselves.  The four key frequencies will be explained.  Further, the nature of the vibration will be discussed; the very high frequency “stress waves”, the resonant nature of the high frequency vibration, and the lower frequency vibration.

Then the discussion will turn to the vibration analysis techniques, including velocity and acceleration spectra and time waveforms, acceleration enveloping (demodulation), and commercial techniques such as PeakVue, SPM, SPM HD, SWAN and SEE.  Each of these techniques will be summarized and compared.

The discussion will include the requirements of the measurement techniques; the mounting of the vibration sensor to ensure that high frequency vibration can be correctly measured.

Remaining life prediction will also be discussed based on the common progression of the failure mode and the ways in which the vibration changes.

It has to be said that this paper and presentation will not further the science of bearing fault diagnosis, but it will help a lot of people develop a much deeper level of understanding.

Note: The physical presentation will utilize a large number of software simulations and 3D animations which will make these topics far easier to understand.