Air Bearings 1

[jmarc]

Hi,

Could anyone please explain to me how air bearings may be used to support a shaft (approx 1" dia) rotating at high speeds (70,000rpm). It seem to me that mechanical bearings would have a limited life at these speeds.

Many thanks.

 

[diamondjim]

jmarc,
You better give some specific loads
to have any meaningful reply. Sounds
like an interesting question.

 

[FredGarvin]

Air bearings are used extensively in aircraft air cycle machines. I would suggest doing a search on either aircraft cabin environmental controls or air cycle machines.

 

[jmarc]

ok, here's some more information regarding the setup:

shaft is approx 100mm long and supports a rotor at each end. one end is an aluminium impeller approx 400g, and the other is an inconel rotor approx 2000g mass. assembly is to be precision machined and balanced in accordance with aerospace standards.

 

[Binary]

I presume you've solved your problem by now???

 

[jmarc]

Yes and no.
Since the bearings are to be use in a prototype, life was not deemed important. We have ended up using some hibrid bearings (stainless cage with ceramic balls).
Any info on non-contact air bearings would, however, still be of interest.
Many thanks,
jmarc.

 

[FredGarvin]

Misc links:

http://nelsonair.com/NA_primer.htm

http://www.memagazine.org/backissues/july98/features/foil/foil.html

http://www.loadpoint.co.uk/site2/aboutairbear.html

 

[jmarc]

Thanks FredGarvin,
That's the information I was after.

 

[Binary]

Also take a look at New Way Bearings

http://www.newwaybearings.com

- Their bushings are the direction I'd have looked for such a project.