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  • help with brass sleeve

    Discussion in 'The main mechanical design forum' started by caligula, Apr 2, 2010.

    1. caligula

      caligula New Member

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      Hi all,
      Could somebody help me with a small design aspect. As part of a college assignment, The torque on a brass sleeved shaft needs to be calculated. I just need to know , what the purpose of the brass sleeve is???? why would you shrink fit a brass sleeve onto a shaft, why not just make the shaft to the correct spec in the first place???
      thanks
      :D
      great site by the way
       
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    3. kenny82

      kenny82 Well-Known Member

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      Hi - i think it needs to be made out of brass because of maybe low friction perhaps.... what are the materials of the shaft and the other part? Perhaps they both need to be made from the same metal and the bearing must be a diferent metal or it will seize up :( i'm not 100% sure on all this so perhaps some others should say their opinions too...
       
    4. mvalenti

      mvalenti Well-Known Member

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      Its a scheme to keep the brass manufacturers in business! Dont fall for it! Go with your gut! Abolish Brass! Ok, levity aside.... I second what Ken said. its probably used as a bushing/bearing of sorts. Could even be ment to wear out so the shaft and/or mating piece doesnt, pull the old off, press on the new...
       
    5. ConnectUTS

      ConnectUTS Active Member

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      caligula:

      Brass and brass filled with a lubricant is a common low cost bearing material. When using brass bushing as bearing it is most common to press the brass bushing into a mounting hole and then allowing the shaft to spin freely inside the bushing.

      I do not know of too many applications where the bushing is press fit on the shaft then allowed to rotate freely in hole on the mounting block or pillow block.

      Why do you wan press the bearing onto the shaft instead of the conventional method?

      When you ask for the torque on a bearing that is not usually a value that you need to be concerned about. Are you really looking for the speed and load rating for the shaft bearing surface?

      If so there are equations that are given in most technical data manuals for sleeve bearings (bushings) that provide this type of information.
       
    6. caligula

      caligula New Member

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      Thanks for the replies.... a big help.
      I can assume that the brass is used as a bearing.
      Thanks again.
       
    7. ConnectUTS

      ConnectUTS Active Member

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      Yes, that is correct. The brass bush would be used as a bearing. Brass is a good material for bearings against steel and many aluminum alloys.

      Niel
       
    8. stewlenox

      stewlenox Active Member

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      Brass is also used in explosive environments to prevent sparks.
       
    9. caligula

      caligula New Member

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      I cant really say why the brass sleeve is a shrink fit as this is a college question? The torque is just an extra calculation that is expected as part of a design.
       
    10. GarethW

      GarethW Chief Clicker Staff Member

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      Here's a link to some Frictional Coefficients for different materials. If your shaft is made from steel, brass is a good bearing material because it has a lower coefficient than e.g steel against steel or aluminium against steel.
       

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