Width of an O-Ring Groove to an Edge 7

[Ramadan Ahmed]

Good evening everyone,

I'm designing an o ring groove for a part I need to seal, I want to ask what is the recommended width from the edge of the O-ring groove to the other edge of the my part. I set a value of 1.25mm as shown in the picture but im not sure if it's a good width or not.

can you please help me with this matter?

Thank You

 

[mfgenggear]

Ramadan
Most of ring manufactures have on their website
Their recommended design recommendations.
I took a look at your sketch and I am not sure what I am looking at. Not a typical design.

 

[btrueblood]

Well, you could make the edge a zero distance, if you thought nothing would let the oring move past that edge. Seal might or might not function without an edge present, can't tell from a cryptic screenshot from a cad program. Comes down to the retention of the seal, and what stress(es) the seal will put on the part under the worst case pressure differential, plus some margin of safety.

 

[david339933]

See Attached.

 

[Ramadan Ahmed]

Good evening,
.
This is a clearer image of my groove, the two selected edges is the width I'm asking about. I set a value of 2mm from the edge of the groove to the edge of the hole I want to seal but I'm not sure how to select a correct value for this.

 

[Ramadan Ahmed]

i went through Parker text book to look for this matter but i could not find anything related to the wall or width from the o-ring groove to the hole or slot that would be sealed

 

[Ramadan Ahmed]

Do you know where in Parker textbook i can find information related to the wall thickness of an o ring groove?

this is a picture to illustrate more about what I'm looking for, i would like to know the wall thickness from the groove side to the hole that would be sealed

 

[EdStainless]

It is related to the scale of the part.
If this is a part that is a couple of cm wide with a <1mm O-ring as a seal, then a 1mm lip might work fine.
Think of the O-ring seal on the back of a wristwatch.
But if this is larger with any real forces on it then you would need something more robust.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[BrianE22]

Is there an internal or external pressure in the part?

 

[Ramadan Ahmed]

There will be no pressure the part is basically a camera which will be used in normal air pressure (1 bar).

but for any future design, is there a way or a standard chart for the size of this lip ?

 

[btrueblood]

Okay, if there is no significant pressure differential across the oring, then the only design consideration for the land width is durability in use (is this likely to get banged up if the lid/cover/whatever is opened frequently) and how difficult it might be to form the groove and land repeatably (if it's a milled groove, you might want to keep it thick to absorb cutting forces and not cave in; if alternatively it's a molded feature, you might get away with a much thinner land width). I don't think you will find recommendations in the Parker handbook, it's going to be a gut call.

 

[BrianE22]

There are "mill cutting force calculators" online that would help you pick a minimum thickness.

 

[SwinnyGG]

I typically try to leave the 'lip' on the inner side of the o-ring feature as the same width as the o-ring groove itself, for forming reasons. On cast, or injection molded parts, the thinner the lip is the harder it is to create, and if it's too thick you just waste material.

Packaging or other concerns sometimes affect that dimension and could result in changes.

There is no general 'rule of thumb' for this dimension that I'm aware of.

 

[mfgenggear]

Just remember, the smaller the thickness of an edge.
The easier it will, can get dings.
It's better to have a little extra wall thickness.
Give your self a liberal edge distance.