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  • Holy Grail of Mechanical Design?

    Discussion in 'The Leisure Lounge' started by Paul T, Oct 21, 2012.

    1. Paul T

      Paul T Well-Known Member

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      Aerostatic or Aerodynamic is only types I'm interested in. I cannot afford aerodynamic foil bearings at this stage.

      I can afford aerostatic porous carbon media air bearings but there is no off the shelf bearing I can use without a complete redesign and lots of money spent.

      It will be cheaper to manufacture a custom set.

      I am just having a little difficulty locating some graphite/carbon with the correct porosity properties. I am told that this material is produces in Japan and Korea mainly for this type of graphite.

      The original patent states "nearly frictionless bearings" and this is what I must have to replicate it.
       
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    3. s.weinberg

      s.weinberg Well-Known Member EngineeringClicks Expert

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      I don't know a whole lot about air bearings, but why carbon? It's non-contact, right? Can't you use any stiff, porous material? I'd think there would be a whole lot of cheaper, better options than carbon.

      I assume you want your porosity carefully controlled, right? Something like straight radial holes throughout? Otherwise, I imagine your air bearing support would be completely irregular.
      So something like filter media would be out. (this kind of thing: https://www.mcmaster.com/porous-carbon/porous-conductive-carbon/ )

      My first inclination is to get something metal, and have it radially 'drilled' on an EDM machine.
      Barring that, see what kind of minimum pore size you can get from a high-end 3D printer and have them printed.

      My non-expert 2 cents
       
    4. Paul T

      Paul T Well-Known Member

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      This is the type of bearing I am trying to replicate.

      Although I am trying to use just one thrust face which will sit almost against the rotor with around 4 micron tolerance.

      This is the recommended setup by OAV.

      They use a 0.0007" / 17 micron axle / bearing gap and <16RMS axle.

      The other side will sit up against the housing.

      I checked out the link your provided. Thanks.

      I emailed McMaster Carr to see what they say.

      Ideally I need 3/4" / 19mm x 4" / 100mm round bar or block.


      I was aware of the many different porosities.

      The air bearing companies are very secretive about their material understandably.
       

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