Grease type for motor lubrication

Polyurea thickener greases are used for their long life and heat resistance but there are alternatives greases that are lithium based. Mobil SHC100 grease was designed with use in motors in mind. You will face the problem of most new motors arrive with a polyurea base grease already in the bearings, You may specify with your rebuilder which grease for them to use but new motors will likely need the bearings cleaned out or effectivly purged if you switch over.

Several companies have had sucess by putting a different style grease fitting on their motors such as a buttonhead fitting. If your motors are the only item with the unique fitting and only the motor grease gun has the corresponding adaptor then only motor grease can be applied unless someone goes out of their way to use the wrong grease. It is also a good idea to install purge fittings in plaCe of the purge plug so that excess grease in the bearings has a way out other than into the windings if the plug was not removed when regreasing.

We use SHELL CYPRINA RA/C3 to grease all our motors. We grease only if our vibration guru ask us to grease and we put just the quantity to lower the signal on his tester.
We just built a new paper machine and all motors are TECO-WESTINGHOUSE new series with a grease discharge device. We plan to make a regreasing program for those motors during running like TECO-WESTINGHOUSE recommend us to do. Their grease recommandations are SHELL ALVANIA R3 (lithium based grease) except for the model ADVANTAGE+ (Chevron SRI-2: polyurea based).
Polyurea based grease is use especialy for extremes conditions, so if your motors runs in "normal conditions", lithium based is OK.
If your motors are equip with a grease discharge device, push the polyurea grease with lithium grease until it overflows and the old grease is entirely replaced. Do it during runing and always check the temperature and vibration. Do one motor at a time.
Finaly, ask to your rebuilder what he does when he rebuilt a motor. What is the configuration of the bearing housing. Can he modifies the bearing housing to be able to regrease the motor.
If you plan to start a motor regreasing program you must know where the grease goes at regreasing and you must give that job to a meticulous grease man.

I hope you have already sorted out the problem, but Kyodo Yushi has great greases for motor applications.
For high temp, low noise, reasonable priced urea grease, we can provide samples too.

Please contact us through our homepage.

Shiro

And in addition to above which is all valid information,
The classic wrong grease electric motor “failure" we observe is the use of heavily tackified greases on cylindrical Roller bearings on the drive end of large electric motors,
Usually this happens,
VA says rollers are skidding
Lube man regreases
VA signal increases indicating rollers becoming hung up in the cage,
It appears heavily tackerfied greases in cylindrical Roller bearings tend to roll over and over as a bow wave in front of the rollers extruding the base oil leaving the soap and the NLGI in the localised areas increases to NLGI 3-4 and the rollers stop turning, grease more intensifies the difficulty,
Indications are burnt grease thickener and base oil running out of the bearing, this can often be rectified on the run by watching with VA and injecting the correct viscosity base oil until VA relaxes then re-apply the correct grease once settled,

because polyurea grease thickeners are thixotropic held molecularly they collapse back to base oil viscosity in the load zone then "reset" to an NLGI viscosity when the pressure is off they are far more suitable for the application,
soap grease have a 3 dimensional lattice that does not collapse and regel again as polyureas can.

Regards Rob S

Molykote G-0100 Multi-purpose motor bearing grease has been developed to meet the increasing demands of the industry.

It’s a mineral oil grease thickened by an urea system that offers a wide temperature range, low noise performance, with excellent corrosion and oxidation preventive properties. With a service temperature range of +338ºF and drop point in excess of 482ºF, the product was tested for the application for over a decade before its commercial introduction. It can extend relubrication intervals vis-à-vis the conventional greases used by the industry for electrical motor bearings, and extend bearing life by preventing prevent premature failures.

Along with its high temperature performance, Molykote G-0100 provides all key requirements that is required by an electric motor bearing greases: excellent low torque characteristics, low oil separation, high speeds capability (DN value 600000 = bearing avg.dia x rpm). low evaporation loss, etc. The product is available in 1 kg and 25 kg packs from Dow Corning.

Satish Agrawal
www.projectsalescorp.com

Just a test

Hi Bill,

There are also greases for high and low speed motors, same lithium based.

To have the best lubrication program we must follow the 4 rights. Right product, Right lube point, Right volume, and Right frequency. The best time to re grease is when the machine is running and also maintain the optimum level of grease in the bearing so that contaminants cannot enter.

Regards,
Danny

We always grease our motors with alvania R2 grease. However we have problems with one of our large induction motors.
The configuration is with a cylindrical roller bearing plus ball bearing in the driving end and cylindrical (NU C3 type) roller bearing in the non driven end.
After 20 or 30 minutes working the bearing starts squealing.
If we add grease it stops squealing for a while 20 or 30 minutes and then starts again.
When squealing up to 6 g's rms is registered (high frequency vibration). However when it stops squealing no vibration is registered.
I am thinking in changing the grease to a NLGI3 instead of the NLGI2.
Has any one experience with such a thing?
Thanks in advance

Bill,

Lithium greases are primarily used due to low unit cost but synthetic lithium complex and polyurea greases offer significant advantages such as reduced power loss, reduced starting torque and extended service life by factor ranging from 2-8 depending on product.

However, performance level differ significantly between lithium complex and polyurea greases in the market.

TREF for lithium greases typically range from 45-55, mineral oil based lithium complex 55-65, synthetic lithium complex 65-85, mineral oil based polyurea 70-90 and synthetic polyurea 85-100. This means that the difference in service life between a mineral oil based lithium grease and a synthetic polyurea can be as much as x8 but the difference between polyurea greases in the market >x2-x4.

The strength of polyurea is primarily service life especially at elevated operating temperatures e.g. f.ex. timber dryers and hot air fans etc.

The strength of lithium complex is service life especially at elevated vibration levels f.ex. fan and pump bearings.

I would recommend synthetic polyurea for smaller greased for life motors and synthetic lithium complex for standard motors, fans and pumps.

Albida EMS2 and Stamina RLS2 are pretty awesome products.

Cheers,
GG