compatible grease for Polyrex EM

[rota2]

Hi all!
We have just received a 450 HP Westinghouse motor that has Polyrex EM grease as the lubricant for it's bearings.I would like to get a compatible grease for this motor, any thoughts on how to begin, or is that information is already out there , I am only to source it?
Thanks

 

[electricpete]

Polyrex EM is sheer stabilized Polyurea thickener.

Google "grease compatibility chart" and you will find a bunch of charts that rate compatibility (based on change in worked penetration) of greases according to their thickener. Sheer stabilized Polyurea is compatible with just about all thickeners (much more so than the non-sheet stabilized).

Even so, those charts have their limitations. There are variations of products within classifications. #1 best approach is to use the same lube. #2 is to have the two greases you want to mix tested for change in worked penetration. #3 is to use the charts, which again will tell you the Polyrex EM is compatible with most greases.

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[DaiWei]

No suprise that the motor came with polyrex EM. It seems to be the lubricant of choice amongst motor manufacturers. Any particular reason you want to change? If you have a strategic lubricant partner, ask them. I am in the process of updating our lubricants (consolidation, rationalization) and have found that the technical people from our supplier have been very forthcoming about compatability between existing lubricants and lubricants they make. Even better, they are very open about not having a compatible lubricant. Most vendors will provide test data if asked to show compatibility.

If you really want a specific lubricant in your bearings, you should specify it in the purchase order.

Ken Culverson

 

[fangohorse]

I think the safest way is to test the change of the penetration after mix.

 

[romke]

polyurea greases are often used in applications where very long grease life (up to fill for life) is required. another consideration is the amount of noise generated by the bearings - with some polyurea greses the noise emissions are far less then with others. based on these arguments the grease was most likely carefully chosen. although other greases may well be compatible, mixing may lead to various unwanted effects that only come to light after very long use. you are better of to stick to the grease advised in this case and only consider a changeover when changing the motorbearings - and then choose a suitable grease together with your lubesupplier, the bearing manufacturer and the motor manufacturer.

if for one reason or another you need to regrease the bearings frequently, my advice would be to pump out as much of the original grease as possible the first time you do so, to avoid mixing greases as far as possible.

compatibilitycharts on the subject of grease mixing should be read with care: there is a large difference between what can be acceptable in the case of chassis lubrication of a shovel (frequent relubrication, after a few times all the original grease is gone) and when regreasing electric motor bearings where only a few shots of grease may be needed every 2000 hrs or so and where thus various greases may be in intimate contact with each other over a very long period.

i

 

[electricpete]

If pumping out the original grease means forcing grease in so that the old grease comes out the drain, you need to be careful of the application. This will create big problems for high D*N applications perhaps above 200,000 mm-rpm. They don't like their housings full and will overheat rapidly.

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