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I'm trying to streamline our greasing at the plant I work at. Right now we have motors with all manner of odd grease in them, and over time I want to re-pack everything so that I know what's out there. Step one is to decide upon some greasing standards.
I figure we have five categories of bearings that I need to worry about at this plant,
- ball/roller bearings in pumps and whatnot, turning at 1700-ish rpm, which a standard wheel/chassis grease should do fine in.
- ball/roller bearings in pillow blocks turning quite slowly as part of conveyors and whatnot. Any cheap grease should work for these, so the same wheel/chassis grease as the first category should work here.
- large self-aligning bearings in grinders that suffer high impact and need a very EP grease.
- ball bearings in regular speed 3 phase squirrel-cage induction motors turning 1700 rpm.
- big ball bearings in 500HP DC motors running variable speeds, as low as 500rpm.

I'm guessing I might need NLGI 3 for the big DC motors, but I don't know. Can I use the same wheel/chassis grease for the high-speed motors? Is there any real drawback to using EP grease in bearings that don't 'need' it?

I just want to come up with two or three greases that I can standardize on, so that I don't have to worry about incompatibility and whatnot.
Actually, I should probably make sure the greases are all compatible just in case one of the foremen decide to grab a grease gun when I'm not looking. They could pump DC motor grease into a pillow block.

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Mike,
Most motors in the last 20 years come from the factory with a NLGI-2 Polyurea grease like Chevron SRI-2 or Mobil Polyrex EM. When you buy shielded or sealed bearings now days from any of the major bearing manufactures they pretty much always come with Polyrex EM in them unless you specify something special. The only exception on motors that I know of is crane manufacturers like Eaton-Yale and Harnischfeger put a lithium grease in their custom motors.
For pillow block bearings, 3600 rpm and below I would recommend a good grade of EP lithium grease like Mobilith AW-2 or Chevron Duralith EP-2. A lithium grease like this should also work in your grinder bearings.
Big ball bearings on your DC motors should also do well on a polyurea NLGI 2 grease, but the Lithium grease would also work well, just don't mix them.
Couplings should get a good coupling grease like KOP-Flex KSG for 1800 rpm and below, and KOP-Flex KHP for over 1800 rpm.
To recap: I would use a Polyurea grease like Mobil Polyrex EM in motors, and a Lithium EP grease like Mobilith AW-2 in pillow blocks. If your big DC motors are vertical type, you might want to use something like Mobilith AW-3 in the bearings.
RM
Thanks for the in-depth reply!

My lube supplier is trying to convince me that their full-synthetic grease will do everything. I'm not convinced.
I'll follow your advice and go with the polyurea for the electric motors.
Lithium certainly seems sensible for the rest of it. I found some information from the Timken company that seems to indicate that some (most?) pillow blocks come with polyurea grease as well. I have to do more investigation on this... if that's the case then I have already contaminated a bunch of them. That would be unfortunate.

More research is required, it seems. Thanks again for your input.. it's appreciated.
RM
I've been following this thread hoping to get some light on how to avoid what MM had done or had risked to do. We have fans on pillow blocks. These are almost 1 year old and on 24x7 duty. We do not know what type of grease has been used and we had no reply from the supplier. We also need to grease the motors. At most the pillow blocks can be dismantled, old greased removed, cleaned and repacked with new appropriate grease but what about those of the motors? Would appreciate some advise. Thank you.
RM
Everything that I have heard so far has indicated that electric motors usually come with a polyurea-based grease in them. However, I found out today that the big DC motors that we run are lubed with lithium grease at the factory, which really annoys me, because now I have to stock a lithium-based non-EP grease for those motors. That's something else I learned today - you should use a non-EP grease for electric motor bearings. The EP additive can apparently cause mayhem in the windings of DC and AC motors, and the brushes of DC motors.
So now my 'streamlined' greasing schedule is requiring:
- Non-EP lithium for the big DC motors
- Non-EP polyurea for every other electric motor
- EP polyurea for the big pillow blocks
- EP lithium for 'general greasing'.
- EP2 calcium-based for the outdoor forklifts.

It's an irritant, to be sure. I'm sorely tempted to repack the bearings of the DC motors, but they're a pig to move about (over two tons each) and they need to be very accurately aligned when they're replaced. I _might_ be able to repack the bearings in-place. Maybe. I'm looking into it.

Anyway, the bottom line for you is that you could probably get away with using a non-EP polyurea-based grease for both your pillow blocks and the motor. Since fans are non-impact (under normal circumstances) I don't think you would need the EP additive in the pillow blocks, and if I'm wrong then someone will surely pop up to correct me. Of course, you should see if the manufacturer of the electric motors will be more helpful than the pillow-block manufacturer and actually tell you what kind of grease they shipped with... just in case.
RM
I was the one _asking_ the question in the first place... I don't claim to be an expert in lubrication. However, I'll add my opinion.
Vertical shafts should have at least NLGI 2 grease in my opinion. Your pumps probably don't _require_ an EP additive but the additive won't hurt them. The EP additive _would_ hurt the motors that drive the pumps. So, if you wanted to streamline you'd probably be best off (again, if I'm wrong hopefully somebody will say so) with a non-EP NLGI 2 polyurea grease. A lithium grease may well be fine, too, as I am finding more and more evidence that lithium and polyurea aren't as incompatible as I had believed. Perhaps someone else who knows more about such things will help us out with this point? How incompatible _are_ lithium and polyurea?
RM
Regarding compatibility I just found the answer to my question.
The 'old' type of polyurea was not compatible with lithium (or barium) based greases. There is a new kind of polyurea, and this 'modern' polyurea _is_ compatible with lithium based greases.
My next question is who the heck decided to name this new polyurea "di-urea"? I thought it was a joke when I first saw it...
RM
Make sure you have checked all oem specs, calibrated your grease guns and labeled them as dedicated to which application,invested in an ultra-sonic grease gun attachment and learned how to use it and never forget the benefit of automatic lubers or professional training offered by a co. like Noria.You obviously are trying to come up with a plan that is made up from the right grease at the right time in the right amount, Noria will train you and your co-workers to get there. Good Luck
RM
Hello,
Kindly allow me to continue with this thread. Referring to an HVAC fan/motor, the manufacturer/supplier recommends grease Shell Alvania 3 or a BP equivalent of Energrease LS3. According to the grease specs this is an NLGI 3. The fan/motor run on 24x7 however the ambient temperature is 14degC for the supply air fan and 25degC for the return air fan. The fan speeds are approx 1000rpm for the supply fan, and approx 800rpm the return fan, with the motors running approx 1470rpm when at 50Hz (VFD). Motor bearings are 6312 and 6212. I'm not convinced this is the right grade of grease. What harm is expected if these bearings are greased using NLGI 3?

Going back to compatibility, what's the effect of using a lithium based to regrease bearings with polyurea at these conditions?
RM
quote:
Originally posted by Rennie:
Hello,
Kindly allow me to continue with this thread. Referring to an HVAC fan/motor, the manufacturer/supplier recommends grease Shell Alvania 3 or a BP equivalent of Energrease LS3. According to the grease specs this is an NLGI 3.

Since the fans run 24/7 it doesn't really matter that the grease is so thick, because it will stay hot. I certainly wouldn't have expected to need a grease that thick unless perhaps the fans are made to tolerate a mounting with the axis vertical? That could be why the grease is so thick. Anyway, a modern polyurea grease is compatible with lithium-based grease.
RM
The effect of using any other grease with polyurea under any condition is catastrophic failure. Most likely a state of saponification will result and your two greases will become some non-lubricating watery mystery. I'm going to consult a few senior tribologists in my co. and get a handle on the grade 3 grease issue and will report that back promptly. I was an eye witness to a grease failure when lithium complex grease was added to an electric motor shipped with polyurea.
RM
quote:
Originally posted by Monolec:
The effect of using any other grease with polyurea under any condition is catastrophic failure.

The grease company literature that I have been perusing differentiates between 'old' polyurea and 'new' polyurea. In fact, I've seen the 'new' polyurea referred to as 'di-urea' which has to be the ickiest name for a grease ever. Anyway, the 'new' polyurea is listed by these grease companies as being compatible with metal-based greases, unlike the 'old' polyurea.
RM
Mike,

The conventional polyurea thickener is pretty much incompatible with everything regardless of whether the base oil is mineral or synthetic. The newer "polyurea" thickened greases are called, as you point out, "di-urea". I agree that the new name could have been chosen better but these thickeners are also referred to as shear stable and the formulation makes them pretty compatible across the board with the lithium and calcium family thickeners. As with all changes in grease, you have to check the chemical compatibility of the base oil. I have seen the earlier polyurea thickened greases turn to rocks when mixed with lithium complex thickened greases and the fluid leached out of the bearing area in short order. At least with those you knew very quickly that you had made a mistake.

I have been investigating greases for different applications in our facilities and suggest you contact your lubricant supplier (technical side not sales) and get data on tests done to show the compatibility. I have done this and am quite satisfied with the results.

Ken Culverson
RM
quote:
Originally posted by DaiWei:
I have been investigating greases for different applications in our facilities and suggest you contact your lubricant supplier (technical side not sales) and get data on tests done to show the compatibility. I have done this and am quite satisfied with the results.

I have done this, and I have standardized on two greases, both from the same manufacturer, and both lithium-based. One is a non-EP grease used solely for electric motors, and the other is an EP synthetic for everything else. I had planned to go with a polyurea for the electric motors due to the evidence that polyurea is very common in electric motors, and the new stuff seems pretty nice, indeed, but my biggest, most expensive and most important motors are General Electric DC drives (200 and 500HP) and the documentation for them specifies a lithium-based non-EP grease, so I figured I might as well go with that for all of my electric motors, then every grease I use is lithium-based. I haven't regretted the decision so far, but time will tell.
RM