O-ring placeholders... Figuring out


#1

Hello guys,

Any o’ring specialist here ?

  • is it better to choose an o’ring slightly smaller than the space where it would sit into, so that it spreads a bit when being installed ? Or should it be the exact same diameter as the channel width ?

  • what width for the channel it sits into compare to the thickness of the o’ring, knowing that it will squeeze even more when you press-fit the tube ?

  • how deep should the channel be ? 1/3 of the o’ring thickness ? 1/2 ?

  • should the channel shape profile be a square or rectangle ?

  • what o’ring shape would do you prefer ? Round, cut square, quad ?

Thank you


#2

There is quite some science behind Orings. The Parker Oring handbook helped me a lot: https://www.parker.com/literature/ORD%205700%20Parker_O-Ring_Handbook.pdf


#3

O-rings are a thing that engineers don’t know by heart. You typically let o-ring manufacturers advise you on that. They all have PDF guidebooks or even online calculators where you input your parameters.


#4

maybe this helps you

https://www.marcorubber.com/o-ring-groove-design-directory.htm


#6

Found this excellent guide explaining with basic words what to look for :

I did not realize that there should be some angle (alpha on the below graph) along the groove depth. It does make sense.


#7

Its true you should have some angle and radii in the corners and probably the most important factor is the extrusion gap. However, keep in mind that o-rings are capable of sealing pressures up to 5,000psi. So in this application its ok to cut corners and simplify things. The parker o-ring handbook is a great resource.