Slow-speed bearings, which in many plants are critical assets, can be very challenging to inspect. However, by using ultrasound technology, the inspection and condition monitoring of slow speed bearings is easier than one might think.
While vibration analysis has long been the instrument of choice to use for bearings and other rotating equipment, ultrasound has also been finding its place has a condition monitoring tool. One particular scenario in which ultrasound may be used first over vibration analysis is with the monitoring of slow speed bearings.
Video: Using Ultrasound to Inspect and Monitor Slow Speed Bearings
Because most high-end ultrasound instruments have a wide sensitivity range and frequency tuning, it is possible to listen to the acoustic quality of the bearing, especially at slower speeds.
In extreme slow speed bearing applications (usually less than 25rpm), the bearing will produce little to no ultrasonic noise. In that case, it is important to not only listen to the sound of the bearing, but more importantly to analyse the recorded ultrasound sound file in a spectrum analysis software, focusing on the time wave form to see if there are any anomalies present.
If “crackling” or “popping” sounds are present, then there is some indication of a deformity occurring. In bearing speeds above 25rpm, it is possible to set a baseline decibel level and trend the associated decibel level readings over time
Video: Example of a Bad Slow Speed Bearing