Bearing Frequencies and Noise
What are Fault Frequencies?
Fault frequencies, sometimes called fault-forcing frequencies are the frequencies at which a faulty part will generate forces on a machine. These forces often manifest themselves as vibrations and/or noise within that machine.
Rolling element bearings are typically constructed with an outer ring, inner ring, cage, and rolling elements. As the bearing operates, at a fixed system rotational speed, vibrations will be generated. These vibrations will correspond with particular bearing fault frequencies. We show you how to calculate them here.
Measuring Fault Frequencies in Rolling Element Bearings
The types of bearing fault frequencies and measurements to consider are:
- Running Speed (RPM) – Speed of the system rotation
- Ball Pass Frequency of Outer Race (BPFO) – outer race failing frequency is a function of the number of rolling elements that pass a particular location on the outer race each time the system makes a full rotation.
- Ball Pass Frequency of Inner Race (BPFI) – inner race failing frequency is a function of the number of rolling elements that pass a particular location on the inner race each time the system makes a full rotation.
- Fundamental Train Frequency (FTF) – cage failing frequency is the number of turns the cage makes each time the system makes a full rotation.
- Ball Spin Frequency (BSF) – rolling element failing frequency is the number of turn a rolling element makes each time the system makes a full rotation.
By closely controlling bearing raceway roundness, form, finish and harmonics, Schatz produces high quality low noise bearings.
Formulas for Calculating for Rolling Element Bearing Fault Frequencies
