Practical Solutions to Machinery and Maintenance Vibration Problems
Chapter 8, Vibration in Bearings
Section 9, Estimating Remaining Bearing Life
The writer views all of the symptoms only as warnings. It is analogous
to measuring just how
For bearings with symptoms of imminent failure, it is suggested that the analyst indicate to the operator: "From the best vibration and IBF knowledge we have today (which is incomplete), the symptoms indicate the machine should be shut down as quickly as possible. However, if you have reasons to want to take your chances and continue running, there is always a possibility that this particular failing bearing may run much longer than symptoms indicate. But at this level, the risk is yours. I can only report that I recommend changing the bearing." For bearings that are deteriorating but not as close to imminent failure, a rough estimate may be given, but in the same spirit as the analogy of the tire.
Operating under the same operating conditions as before, it is reasonably
possible to predict how long a bearing will last if the symptoms and
data are compared with that bearing's previous symptoms of failure.
Most of the time, however, this experience is not available, so it is
not recommended that specific bearing life predictions be made. Many
factors other than bearing conditions, such as speed, also affect decisions
as to whether a bearing should be changed or allowed to run. Try to
avoid specific time predictions, since errors in time prediction often
lead to a loss of credibility even though the defective bearing has
been correctly identified.
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