Unlubricated, cryogenic bearing 1

[iainuts]

We've been having problems with some bearings in cryogenic hydrogen service ( -420 F). The bearing is in the liquid hydrogen flow stream and can not be lubricated.
Size: 20 mm ID, 47 mm OD, 14 mm wide.
Style: Roller
Speed: 12,000 RPM
No lubricant.
Operating temp: -420 F
Load: Indeterminate, supports rotating pump shaft. No large radial loads. Weight supported may be aprox. 10 pounds.

I've gotten some quotes back on a replacement bearing.
1'st quote:
Ceramic rollers, corrosion resistant high nitrogen steel, Teflon impregnated PEEK cage, C5 clearance.

2'nd quote:
Corrosion resistant, high nitrogen steel rings and rollers, glass filled Teflon cage with molybdenum disulfide added, C5 clearance.

Both bearings have the same load rating which is on the order of 5000 pounds.

Any thoughts on what might work best for this application would be appreciated.

 

[diskullman]

How about a standard bearing, C4 clearance, with graphite solid lubricant, heat treated for corrosion resistance. Look up Unique Technologies

http://www.uniquetechnologies.com

the whole process may add $50 to the standard bearing, so it would be an inexpensive test

Russell Giuliano

 

[iainuts]

Hi Russell. From your web site, it says:

Bearings using Cobra Solid Lubricants maintain constant low starting torque even with temperatures in the cryogenic range.
(also)
Low temperature – as low as minus 250F

What minimum temperature has this lubricant been tested at?

Who makes your bearing parts? (races, balls, etc...)

Do you have any experience with similar (cryogenic) applications?

 

[diskullman]

I am not with Unique Technologies, contact them directly. You may supply your own bearing for treatment with Cobra Lubricant. Ask for Gary

Russell Giuliano

 

[volpegrigia]

The bearings they quoted you are designed to operate in cryogenic fluid and they have been tested in the shuttle turbo pumps (used to fuel the motors with both components, fuel and oxidizer).
The lubrication in such application is critical specifically due to the fact that the cryogenic fluid in the contact zone (ball raceway contact) vaporizes forming bubbles (Some cavitations effects with peculiar properties). NASA has several papers on the subject (specifically the bearings for turbo pumps, their failures and method to prevent them) that can be of help to you.

 

[iainuts]

Hi Russ,
Sorry if I made some error in assuming you worked for Unique Technologies. I guess because you've signed your name with that heading, such as in this thread that I'm confused:

http://www.eng-tips.com/viewthread.cfm?qid=116417

And because there's a Russ in customer service at UT. Oh well, my appologies.

Hi Volpe, The bearings I've been quoted haven't been tested in the shuttle, though I've heard about the ones you're refering to. Can you provide a link to the papers? I'd be interested in reading more about them.

 

[diskullman]

No problem, I was FORMERLY with them, and left on good terms. They have an amazing product that works well with many difficult applications. Your temperature range may be lower than they have seen in the past, however it may be worthwhile to try a test sample, if that can be facilitated without any harm.

Russell Giuliano

 

[JamesBarlow]

"Hi Volpe, The bearings I've been quoted haven't been tested in the shuttle, though I've heard about the ones you're refering to. Can you provide a link to the papers? I'd be interested in reading more about them."

http://gltrs.grc.nasa.gov/

The above link is a little tough to get exactly what you want, since NASA has papers on nearly every subject you can imagine, but it's an amazing source of free papers written by some of the best minds in the various industries.

 

[pagheca]

Hi,
I have a similar problem, and was wondering if you found a solution. In my case, the speed is very low but we need a system running for very long time and a severe constraint on max friction. Magnetic bearings and Superconducting magnetics bearings cannot be used in our case.
Any pointer to manufacturers of bearings for cryogenics application would be welcome.
Regards

 

[iainuts]

Hi pagheca. I found a solution but haven't tested it out yet. SKF is recommending ceramic ball bearing with stainless races (first quote above). Lead time is 5 to 6 months and we still don't have them on order as we're researching alternatives still.

 

[ischgl99]

If you haven't already, might want to try Barden Bearings as well, they have experience with many unusual applications.

http://www.bardenbearings.com

 

[unclesyd]

Never purchased any ceramic bearings from them but have purchased many miniature bearings.
They have both full ceramic and Hybrid bearings.

You might give them a call and see what they have to offer.

http://www.bocabearings.com/main1.aspx?p=showsearchforpage&cat=industry&label=cb