Custom Molded O-Rings for Specific Applications

Customer Problem: A manufacturer of military and aerospace systems was having trouble with seal retention during assembly.  They were using standard round O-rings.  Because of hoop stress, round O-rings tend to rebound to a circular shape causing them to pull out of non-circular groove paths.  The current off-the-shelf O-rings were popping out of the groove.  This led to assembly issues and could potentially cause pinching or missing seals.

Customer Requirements: 

  • An elastomer needed to be selected that was chemically compatible with the
    coolant fluid.  
  • The seal had to hold 50 psi operating pressure with 150 psi test pressure. 
  • The seal needed to conform to the path of the groove design.
  • The seal needed to meet typical outdoor environmental temperatures.

Solution: It was determined a custom molded shaped seal with a round cross-section out of EPDM elastomer was the best solution.  Using a custom shape alleviated the hoop stress allowing the seal to stay in the groove during assembly.  EPDM has excellent chemical resistance to many coolant fluids and met the temperature requirements.  By utilizing a readily available compound, multiple sizes and variations were ran for development and testing, leading to a design produced in several different configurations. 

Conclusion: Sealing Devices can offer custom molded O-rings and Seals to fit where standard off-the-shelf solutions will not work while still providing the sealing capability for specific applications.  Sealing Devices advised on the groove geometry, seal geometry, and tooling.