Stainless Needle Bearings

[AdamUu]

I am designing a valve for use in liquid oxygen. I want to use needle bearings but they need to be stainless steel for fluid compatibility reasons. My search for off the shelf solutions has come up blank and custom bearing quotes have been prohibitively expensive.

Does anyone know who makes stainless radial needle bearings? I need approximately 5/8 to 3/4" ID.

 

[MikeHalloran]

Even stainless needle bearings need grease to stay alive.
That alone may be a problem in oxygen service.
Given the presence of grease, you don't need stainless.
But again, the grease itself may be a problem.
How do you feel about plain teflon bushings?




Mike Halloran
Pembroke Pines, FL, USA

 

[AdamUu]

I need stainless for following reasons:

Flammability - Steel combusts much more readily than stainless. Yes, they will both burn with enough motivation.

Cryo toughness - steel can become brittle at -290F (liquid oxygen). Some alloy steels can maintain usable toughness at cryo but probably not hardened steels.

Corrosion resistance - Considering the cryo temps, lube is out of the question (Molycote is OK).


We are considering some teflon filled bronze bushings. Loads are too high for a plain teflon bushing.

The application is 1/4 turn at slow speeds and only a few thousand cycles. It is my hope that an un-lubricated bearing would last. Our goal is to keep the friction as low as possible to minimize the size of the actuator and increase reliability.

 

[caoimhin1]

I would def heed MikeHalloran's advice and go for a plain bearing. Stainless or bronze backed, with PTFE lining. High load and slow oscillation means plain bearing. Might need to pay a bit for a bushing to cope with the cryo requirements, but better than paying for a bespoke stainless needle.

 

[unclesyd]

Just one of many that sell cam follower bearings which might work governed by the information given in the OP. There is Krytox grease for O2 though not for cryogenic or high temperature. Moly is used for lubrication at Cryogenic temperatures but I;m not sure about in O2. If it is used it probably would have to sputter on since any other method uses an organic carrier. I would look at Boron Nitride, white graphite, as a possibility for lubrication.

http://www.wbparts.com/rfq/3110-00-925-8601.html

http://www.bearingtrends.com/bearin...els-440c-vs-52100-in-a-corrosive-environment-

http://www2.dupont.com/Lubricants/en_US/uses_apps/Product_Guide.html

 

[AdamUu]

Thanks for the input. It looks like we may have to settle for the teflon impregnated bronze bushing.

The cam follower is interesting but i don't think I can use that packaging. At least is proves stainless needles are being manufactured. I had a vendor quote custom bearings at $400 ea in lots of 180. I'll get fires if I try to spend $72,000 on bearings.

 

[unclesyd]

if you pushed to use a needle bearing you need to look around as they come in all different flavors and sizes. Check the different manufacturers catalogue of these bearings and see if the have a configuration that meets your requirements.

It's here or there, all one have to do is find it. This or something similar spoken by Pogo (1865).