We all know that ultrasound is one of the most effective technologies for bearing inspection and condition monitoring. But just how easy is it?
The answer, of course, depends on many factors but, as a general rule, inspecting bearings with an ultrasonic instrument is very straightforward: establish contact between the instrument and the bearing (normally a contact module or magnetic module are used) and listen to it.
Video: How to inspect bearings use ultrasound
Sometimes, just by simply listening you will be able to understand if there is something wrong with the bearing. A bearing in good condition will present a smooth rushing sound while a “bad” bearing will present differences in amplitude and a more “rough” sound.
Video: Example of Good Bearing
Video: Example of Bad Bearing
An inspector should also rely on the decibel readings (dB) from the bearing. Normally each bearing will have a dB baseline which represents a good condition and adequate lubrication. Knowing the baseline value and comparing it to the dB reading on the instrument, we can easily how is the bearing’s condition. Normally this is what dB levels represent, against the baseline:
- An 8 dB gain over baseline indicates pre-failure or lack of lubrication.
- A 12 dB increase establishes the very beginning of the failure mode.
- A 16 dB gain indicates advanced failure condition
- A 35-50 dB gain warns of catastrophic failure.
For a more advanced analysis and diagnostic, it is also possible with some instruments to record the sound from the bearing and then analyse it in a sound spectrum software. This is especially useful for slow speed bearings.
Video: Faulty Slow Speed Bearing