Detecting bearing failure modes at higher frequencies, and earlier in their progression, is key to extending the bearing life and ensuring the reliability of a machine.

Bearing failure generally progresses through four main stages and across a wide range of frequencies.  Vibration monitoring will typically enable identification of Stages 2 to 4 of bearing failure. By this time, irreversible bearing damage has occurred, and management of the asset is the primary goal. Adding ultrasound detection to a condition monitoring program makes it possible to detect bearing failures in Stage 1 and optimize lubrication to stave off permanent damage and extend the life of production assets.

• Stage 1, manifesting symptoms between 20 – 40 kHz, can most easily be detected through ultrasonic monitoring and is mitigated through precision lubrication practices. While bearing wear fatigue is inevitable in the long term, proper lubrication will extend the life of bearings to the degree possible.
• By the time a bearing has reached Stage 2, damage to the bearings has already occurred and is visible upon inspection. It is critical to at the very least identify the signs at this stage, if not plan maintenance to address it at the next planned shutdown. Maintenance may include replacing the bearing, depending on the fault condition and its severity.
• Stage 3 is a worsening of the condition, resulting in severe bearing damage and visible peaks at the defect frequencies, in addition to higher energy at the bearing resonances. At this stage, bearing performance significantly declines and can more directly affect the process being run by the machine.  If the next planned shutdown is not in the near future, maintenance should occur immediately to prevent progression to stage 4.
• Finally, Stage 4 is the most severe stage of bearing failure and can result in a total breakdown and inability to support the load or operate effectively. If maintenance actions are not taken immediately, a catastrophic failure can occur.

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