How to manage Small Sealed for life Bearings in Motors
How long do Sealed Bearings Last for?
My experience tells me that small motors which often are critical to processes don’t have an asset strategy and are left to “Run to Failure”
Why? The shear number of these relatively cheap and off the
shelf motors means many facilities choose to “Run to Failure”,
but often the accumulative downtime means significant production
losses are racked up over a year.
Best Practice Lubrication extends to Sealed Bearings as half of Motor Failures are Bearing related, and Sub optimal Lubrication being the top failure mode. So the numbers stack up to make Sealed Bearing Lubrication a top priority.
A small motor up to to 22kW is the economical replacement size before Overhauling.
These motors nearly always has Sealed for Life Bearings, but that Life isn’t the life of the bearing it’s the grease.
Grease Service Factor typically means Sealed Bearings deplete the grease depending on the environment in about 10,000 hours.
Many motors don’t run continuously so even at less than 1000 hours per year the grease life is 10 years. Multiply the several hundred in a small facility the failure rate can be 10% in easy numbers.
Can your plant accept a failure every month maybe more often and suffer downtime because no asset strategy exists?
Early in my career our strategy was to attempt to overhauls motors and replace bearings, but the Planning & Scheduling is a nightmare.
Where do you start, what was overhauled last year, what resources do I have in the shutdown?
Time Based overhauls don’t work because it’s costly, every machine is in a different environment and Maintenance induced failures are a problem (That’s the settling period after Shutdown, more downtime)
We implemented Vibration Analysis in an attempt to pick off the bad ones, and schedule overhauls but the Shear number of critical small motors makes this often uneconomical and VA is focused on the larger rotating assets.
In this Example all the bearings are from the same machine, same age, same running hours in the same environment and Load:
I replaced all the bearing this morning
This Sealed bearing has suffered Grease Depletion and the thickener remains.
In this Bearing the Grease has suffered Moisture Ingress and Grease has depleted.
In this Sealed Bearing the Grease has depleted and the Cage has failed. The bearing is at risk of complete failure and secondary damage & downtime.
This example shows Sealed Bearings even on the same machine & conditions decay to failure at different rates.
So time based replacements DON'T WORK, and there's way too many to have on your Vibration Analysis Database.
So What to do?
When bearings start to suffer grease depletion the friction increases, and that friction is best suited to be measured with Ultra sonics.
Using a LubExpert instrument with your existing Lubrication resourced program those Sealed bearings can be measured and trended. What’s the bonus is Time Waveform & Spectra Data similar to Vibration Analysis can be collected in the background and analyzed in software with automated alarm reports.
Quoting Haris from SDT, “Sending the Nurses instead of Doctors for the first line of Defense”
So your overhauls or replacements can be condition based keeping a minimized Stock/Rotables, that strategy can be easily setup with 3Phi Reliability Best Practice Motor Management Audit.
You gain control while minimizing the total cost of Ownership.
So think What do you do with Conveyors, Oil Pumps, Fans, Pumps, Agitators, Rotary Valves, Chain drives, Augers, Elevators, and Blowers?
When the Nurse detects an Alarm then you send for the Doctor, and analyze the Time Wave form and Spectra Data. So this strategy compliments your Vibration Analysis program and actually makes it more efficient.
https://www.3phi-reliability.com/optimal-lubrication has integrated the LubExpert into Best Practice Motor Management as
Lubrication is a large contributor to Motor/Asset failure approximately 50%.
3Phi Reliability are trained & qualified LubExpert Implementers, and combined with Motor Circuit testing have a track record of eliminating motor failures and returning Energy Savings.
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