Good Bearing

FFT of a good bearing. Since there are no defects, the sound will be a smooth rushing sound.

The spectral view will not show any harmonics or large peaks.

Bad Bearing

This is an FFT spectrum view of a bad bearing. As a bearing enters the failure stage there is a rise in the decibel level of 12- 16 dB over a baseline. This rise in amplitude is usually accompanied by a change in the sound quality.

Note that on this bearing we can now observe fault frequency harmonics which we can use to confirm & analyze. The integrated bearing fault calculator can confirm inner/outer ring, ball pass or cage defects.