Using ultrasound to improve lubrication practices
Keeping a handle on lubrication is easy, right? All one needs to do is make sure the right lubricant is used in the right amount and at the right time. Not so fast; if only it were that simple. Author: Adrian Messer – UE Systems
It has been estimated that 60-90% of all bearing failures are lubrication related. Bearing failures most often lead to unplanned downtime which can impact production as well as affect all related components around the bearing. Downtime is costly. While the costs varies by incident and by plant, it can add up. Since the most common cause of bearing failure is lubrication related, it’s clear to see that lubrication is serious business. And for the longest time, that “serious business” has been conducted in a way that on its face makes perfect sense – but in fact borders on haphazard.
Many technicians, unfortunately, have relied on “preventive”, time-based lubrication alone. That is, every X number of months, the grease gun comes out, and the bearings are lubricated. After all, under-lubrications can be lethal, causing equipment failure, costly repairs and replacements, significant unplanned downtime, and lost profits. But by relying solely on time-based lubrication, or even a combination of planned maintenance and temperature readings to serve as a proxy for lubrication status, one runs the risk of something just as bad, if not worse: over-lubrication. In fact over-lubrication has been reported both anecdotally and in presentations at various conferences to be the primary cause of premature bearing failure.
Relying on time-based, periodic lubrication assumes bearings need to be greased at defined time periods. Often this evolves into a well-intentioned guessing game at best. Adding more lubrication to a bearing that is already adequately greased is a real risk.
By using ultrasound technology (along with standard practices such as removing old grease and replacing it with new), technicians can combine standard time-based maintenance with condition-based, predictive maintenance, gaining in the process both a clearer picture of what’s really going on and better reliability.
How ultrasound works
Ultrasonic equipment detects airborne and structure borne ultrasounds normally inaudible to the human ear and electronically “transposes” them into audible signals that a tech can hear through headphones and view on a display panel as decibel (dB) levels. In some instruments, such as the Ultraprobe® 15,000 Touch, the received sound can also be viewed on a spectral analysis screen. With this information a trained technician can interpret the bearing condition in order to determine what, if any, corrective action is needed.
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Another Time Wave Form of a bearing in the process of being lubed over 13 seconds. Again, a distinct before and after lube can be seen.
Bearing beginning of over lube: Bearing lube example I:
This is a Time Wave Form of a recorded ultrasound of a bearing in the process of being lubed. The approximately 1 minute sound files shows the bearing before and after lubrication.
Bearing lube example II:
LUBE MAGAZINE NO.133 JUNE 2016
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