Skip to main content

Read our primer articles on Grease Guns and Oil Sight Glasses.

How can we lubricate our large motors and know how much grease is in the bearing cavity without over greasing. Ultasonics only tells us when we have enough lubricant to quiet the bearing, it does not tell us we have filled the cavity to the proper level and have the optimum frequency for re-lubrication.
Original Post

Replies sorted oldest to newest

Usually SKF and FAG has the methods but as a rule of the thumb you can provide a first fill of 25-40% of the free space of the bearing and relubrication qty of 10% of first fill.
The time will be calculated depending on the K factor and other acondition listed in FAG and SKF Manual or established by condition monitoring method like SPM or temp and Vibration if it is very critical
Provided that the bearing was filled correctly when it was assembled then ultrasound should provide a reliable method of relubrication. By only using enough grease to quiet the bearing and using the ultrasound to monitor when the noise level increases to a point in which the bearing requires more grease you will over time find you use less grease and increase reliability. Traditional regreasing calculations usually result in the bearing being overgreased after the route and under greased by the next time it comes up on the schedule. By increasing your monitoring and only greasing what needs it you willimprove you results. I would also suggest that you install a different grease fitting on your motors than is commonly used on other items in your plant so that only those involved in electric motor greasing may grease tham to prevent introduction of the wrong grease.
If you have motors that haven't been lubricated for a couple of years and the last time they were lubricated #2 Lithum Complex grease was used which of sourse is not a motor bearing grease but you are now going to lubricate with Exxon Polyrex Em motor bearing grease . Is it better to wait and not lubricate and just let bearings go out or can we purge existing grease with the Exxon Polyrex and get sufficient results . Would appreciate opinions .
You can either just wait until teh bearings go out or continue greasing with the lithium until they do. You should not try to grease with the Polyrex and purge out the Lithium as you are asking for failures. Mobiilith SHC 100 grease is lithium based and is designed for use in electric motors that may be a better option than a grease with mineral oil base and should be compatable with the grease that is in teh bearings now. If you switch to the Polyrex EM for new installations you need to clearly identify which motors are using what type of grease. One way is to put a different style grease fitting on the newer motors so teh old grease cannot be easily put in them. We use button head grease fittings on our motors and standard grease fitting on everything else.
The goal is not to put the correct amount of grease in the cavity - the goal is to lubricate the bearing properly. Pay attention to what your ultrasound is telling you and use that to decide when to add grease. Over the life of the motor you will probably introduce grease onto the windings. This is not the killer it used to be. Motors can take handle this better than they used to. Trust the ultrasonic to tell you what to do and use vibration analysis to back if up if you have that capability.
Hi Andy,

This motor I think is very expensive, right. To protect it, you have ultrasonics. How about installing Memolub automatic lubricator? From motor manual it says relube this much grease after this much time. Dont gamble with manual method, if its not over it is under lubrication. Usually our 240cc of grease can be use for 6months to 1year. Ejecting same amount of grease from first to the last stroke, grease level is always in optimal. Pls call a Memolub distributor for a demo and purchase one to protect your investment. You dont need ultasonics if you have Memolub.

Regards,
Danny
And how does this system monitor the amount of grease in the bearing? Does it monitor the bearing temp? Does it monitor vibration? I doubt it.

The best practice is to stick with your ultrasonic monitor. When you have applied the correct amount of grease the bearing will quiet down. Using a automatic lubricator will most likely lead to a severe over lubrication situation and overheated bearings.
And how does this system monitor the amount of grease in the bearing?

``My answer is no. No monitoring features but it can eject right volume.``

Does it monitor the bearing temp?

``My answer is no. But it can eject at right frequency.``

Does it monitor vibration?

``My answer is no again. Right product, right point, right volume and right frequency does not need ultrasonic.``

Proper lubrication is the answer.

How we do it?

Lets say a motor needs 240cc in one year. If you are using grease gun maybe we will pump it all in one time, or maybe 120cc every 6 months or 60cc every 3months frequency. Do you think it is the proper way?

The best frequency is keeping the grease level in optimal. How again?

Since we know that motor consumes 240cc in one year so we need to devide 240cc by 365 days.

This amount of grease ejected equally at daily frequency will keep the grease in optimum level. Agree? Memolub with its 350psi can be fitted directly or remotely to grease fitting or lube point. It uses cartridges and fitted to lube points directly, the added benefits here is eliminating contamination.

So if we have no contamination, right grease for the bearing, grease level in optimal all the time, of course there will be no overheating, no vibration and no bearing failure. And no need for other gadgets.

And how does this system monitor the amount of grease in the bearing?

``We visited our client during their shutdown free of charge, visually checking the bearing to know if the ejection needs adjustment.``

Regards,

Danny
Post
attend Reliable Plant 2024
×
×
×
×
Link copied to your clipboard.
×