Bearings are probably the more complex designed component of any rotating equipment; yet, they are the most misunderstood by the maintenance practitioners who handle them on a daily basis.” —Holcombe Baird, Reliability Center, Inc.
If experiencing premature bearing failures, you should not only look at bearing lubrication practices but also at bearing installation practices. When using an induction heater it is important to make sure that the heating is steady and even; fast is not always good, especially if you do not know what is happening with the temperature of the OD of your bearing. Remember that the inner race heats faster than the outer race. Precision bearings are prime candidates.
In the picture above, on the left you see a single temperature probe, placed on the ID of the bearing, and by the time the temperature of the ID reaches 110° C, the temperature of the OD is only 60° C. This could be a huge problem if the clearance between the ball or roller bearings and the raceways of the ID and OD is not enough to handle the temperature difference. In these cases the bearing balls or rollers get squeezed between the OD and ID damaging the bearing before it is even installed.
Read my entire article at Reliable Plant
Many thanks to Rick Trichka with TM Induction Heating and to Robert “Bob” Latino and Holcome Baird at Reliability Center, Inc. for their input.
by Ana Maria Delgado, CRL
Rotating equipment produces a sound (ultrasonic) signature during operation. This signature can be measured and trended over time. As the machine components begin to fail a change in the ultrasonic signature will occur. The change in sound level can be used to alarm that could be related to lubrication or bearing damage. A key factor to using an ultrasound tool successfully to determine machine health is collecting the measurements at the same location every time. The first step is to identify a measurement test point for each bearing to be monitored. One method for data collection is to use a magnet that should be attached to a metal pad epoxied to the measurement location. The use of a magnet and mounting pad will allow for repeatable and consistent data for accurate trending and alarming. If access to measurement locations is restricted, then a sensor can be permanently installed so that measurements can be taken remotely. Ultrasound is an extremely valuable tool which can be used to detect bearing problems with slow speed applications.
Ultrasound is an important part of any reliability based condition monitoring program and can provide early warning of mechanical failure. This early warning can lead to reduced downtime and increased plant reliability.
by Dave Leach CRL CMRT CMRP