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  • Sealing a rectangular hole on a cylinder

    Discussion in 'The main mechanical design forum' started by Mechanic77, Feb 16, 2019.

    1. Mechanic77

      Mechanic77 New Member

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      Hi all,

      I'm a Mechanical design engineer, new to design for sealing.

      I was given a task at my workplace, to design a plastic cylinder (made of ABS+PC) with a rectangular hole (for a lens made of HDPE).
      The hole for the lens should be sealed to the level of IPx5, without the use of screws/bolts/any kind of fasteners.

      please see the attached picture:
      Sealing the lens.jpg


      the main issue I identified is that if I will use any kind of face gasket, it will be very difficult to seal the surfaces at the sides.

      Assuming I will manage to create some kind of force to press the gasket at the front area of the lens (using an additional plastic part, on the inside, which will press the lens against the front area of the enclosure - a "sandwich" configuration: Lens between 2 plastic parts), there will be no such force to press the gasket against the plastic at the sides.

      1. Any ideas on how to solve this?
      2. How can I ensure proper sealing in such challenging design configuration, around the entire lens?
      3. Could someone please refer me to design guide(s) for sealing without fasteners? Does this method (not using fasteners) give reliable results, or there is no way to really seal products reliably without the use of fasteners?

      Thanks in advance!
       
    2.  
    3. Erich

      Erich Well-Known Member

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      I have one word for you. Adhesives.
       
    4. Mark_Armstrong

      Mark_Armstrong Active Member

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      Not my line of work, but I'd look to the adhesives used for attaching windshields to vehicles. Everything is glued in nowadays.
       
    5. Mechanic77

      Mechanic77 New Member

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      Thanks for the answer Erich. It is of course obvious that adhesives will do the work. I was wondering if maybe there was a different way, because for some reason at my work place those in charge try to avoid using this fastening method. maybe because of lack of experience with adhesives.


      Thanks Mark, I'll look into it.
       
    6. s.weinberg

      s.weinberg Well-Known Member EngineeringClicks Expert

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      Welcome to the wonderful world of sealing. Prepare to tear your hair out. Sealing somehow always seems to find a way to suck.

      I'm going to second the use of tapes/adhesives. You'll still have issues, but less than you will otherwise.

      If the powers that be are insistent that you cannot fasten anything in any way, I'm not sure why a cylindrical sleeve wouldn't give you relatively even pressure on the face. Alternately, wall thickness permitting, you could try to get a seal into the wall of the lens or cylinder, and press them together.
       
    7. Mark_Armstrong

      Mark_Armstrong Active Member

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      We've all been at the point where we try to apply new things. The best thing I have found is to use your vendors for legwork.

      Contact several with the application and see what they can offer. Compare their responses and see if any seem to be overpromising.

      Get some samples and try some experiments with the materials.

      It sounds like it will be a fun project.
       
    8. Mark_Armstrong

      Mark_Armstrong Active Member

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      Wait... Do they want the lens to be removable/replaceable?
       
    9. Mechanic77

      Mechanic77 New Member

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      Thanks a lot for your answer!
       
    10. Mechanic77

      Mechanic77 New Member

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      Hi, thanks for your answer,
      No they want the lens to be static, without any option to remove it.

      It's a good idea, I will try to consult our vendors regarding a solution.
       

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