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Pressure coating

  1. Jan 15, 2014 #1
    I have assembled a simple roller transfer mechanism for applying thread sealant ( toothpaste consistency ) to external threads. Since I did not get uniform coating, I placed the unevenly coated component in a small pressure vessel at 3 kg/cm2, hoping that the pressure would even out the uneven layer.However, the coating remains unchanged. Why is this so ?
  2. jcsd
  3. Jan 16, 2014 #2


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    Is it a commercially available sealant, manufacturer, product name ?

    I would expect external pressure to have an effect on a fluid that contained gas bubbles. The thread sealant I use is an incompressible liquid without gas bubbles.

    You might get the fluid to spread by vibrating the bolt, maybe ultrasonic. That could encourage a liquid to flow and wet all the thread surface.

    If your roller applicator rolls with the bolt then a fluid may not be spread evenly on the roller or bolt. By having a differential rotation between the bolt and the application roller you should paint a more uniform coating by equalising the fluid distribution on the application roller(s).
  4. Jan 16, 2014 #3
    Thank you.
    Yes, Vibraseal.
    The bolt rotates freely on it's axis & moves against a (fixed) rubber roller axially rotating in the opposite direction.
    The point is,if an irregular blob of grease is placed in a small pressure chamber & pressurised at, say 3 kg/cm2,would it not spread itself uniformly against the inner walls?This does not seem to be happening.
  5. Jan 16, 2014 #4


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    I think you should try to explain why you think the grease would somehow find internal surfaces when under pressure, when it could not find them at atmospheric pressure.

    What is it about the geometry of the grease blob that is effected by pressure ?

    Where have you seen environmental pressure spread a grease ?
  6. Jan 16, 2014 #5
    Perhaps my thinking has been very wrong on this & a pressure differential is required for the grease to change shape.Thanks for making me think.
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