Is there any O-rings suitable for vacuum sealing?

I have been using vacuum work holding for some large plate work for the past year or so. Any time I have a thru hole I will mill a gasket groove and fill it with gasket stock.

I have a job in now that have more holes at random intervals making it hard to isolate a group of holes altogether. I was wondering if anyone has had any luck with any actual O-rings? I know the gasket material is softer than an O-ring but if i could get away with pushing a ring into a groove rather than cutting and laying in a small loop of gasket material I could save a ton of time.

Anyone have any source for O-rings made of gasket?

A neoprene or similar O ring will absolutely hold a vacuum. I have some equipment that is pumped down to a 5 micron vacuum with a diffusion pump and it is sealed with nothing but an O ring and a little Dow Corning vacuum pump grease. You can buy "endless" O ring material which could meet your need. I have made some vacuum clamps by milling a groove with ball nose mills and dropping in an o ring. Works great.

I used to buy endless o-ring from the guys I got Evinrude/Johnson parts from. The old, small OBs use it to gasket the halves of the lower gear-case. IIRC, choices were Neoprene and Viton, but it wouldn't surprise me if orange hi-temp silicone was available from them or your tooling guys. btw, 'Ultra Blue' is my choice when a dab is needed to seal butt ends, but may not be needed with a vacuum setup.

A properly designed o-ring groove will let the o-ring compress until you have 100% metal to metal contact. Download the Parker catalog with all the design details. https://www.parker.com/literature/ORD 5700 Parker_O-Ring_Handbook.pdf

As Crossthread mentioned, O Rings work for vacuum. That is one of the standard uses for them, depending on the level of vacuum needed and issues such as cleanliness. The design of the O Ring groove is somewhat to very important, depending on the application. O rings of various types may be obtained from Mcmaster.com. A source of both a wide variety of sealing materials, and also information on O Ring sizes, compounds, and gland design is Marco Rubber - O-Ring, Seal, Fitting, & Component Super Store (Kalrez, Viton, Parker, Metric, Custom). They are distributers of sealing materials ranging from garden variety to the highest end sorts. They have always been very helpful and easy to talk with. One thing to note: O Rings are usually specified by the INNER diameter and nominal thickness of the rubber cross section. There are detailed guides on Marco Rubber for designing glands for different sealing configurations. For the application you describe, it will not be difficult.

Also, as Crossthread mentioned, one can obtain rolls of O Ring stock which can be cut to length (usually at an angle) and
then glued together to make a custom size. See McMaster-Carr. Superglue might be adequate for your need. One can obtain kits of various sizes in a variety of compounds from mcmaster.com. Search on "O Ring Kit".

Good luck!
Michael

The cross section tolerance on O rings is half that of cord stock so because of that alone I would not be building my own, get the real thing. Just use the softest ones you can get and factor .002"- .003" compression.

Quite common to get down to 10 ee-5 torr with buna rings if you don't set the joint up to fail with a virtual leak. There has to be a "pump-out" groove or two, to the high vac side on any vacuum joint. Ditto for blind hardware on the high vac side.. their always has to be a leak path for entrained gas. Moisture ie especially evil.. water goes to ice at room temp under vacuum, and then slowly sublimates away..... slowly..... very slowly.

We always use Viton seals. They last longer and can tolerate higher temperatures in the workpiece being held.

I think the point of the OP is being missed.

Yes, O-rings are standard sealing devices for vacuum. BUT! Have you ever tried to get 20 o-rings to seal at once with only the vacuum it's self to initiate the compression?

Vacuum chucks do need "soft" o-rings. Mu preference is to make sealing rings from tubular stock, Nice and compliant. But there you are again needing to make up a bunch of sealing rings.

I'm sure someone like Boker could stamp out as many soft seals as one would care to order. but getting 30-40 [ieces at 3/4" Id and 1 inch OD for example, I don't know .

I've not run across any sources for ready made vacuum sealing rings such as might be useful for vacuum chucking.

My application is glass, but it's the same all in all. Just when I make a mistake and put a hard o-ring next to a soft sealing ring, the glass breaks! ;-)

Use low durometer silicone or similar o-rings. Remember though, you can have the biggest pump in the world and you still only get 14.7 lbs/in^2 pushing the parts together.

Regular o-rings are 70 durometer (Shore A), you might want to try around 50 durometer. The Parker book is going to give you squeeze values around 25%, but that's way more force than you need because vacuum chucking can tolerate leakage. You won't be able to go all the way down to .002-.003" compression because of the tolerance on the o-ring thickness, but you might get away with a 5% squeeze and put a lot less force on the glass. The thinner o-rings can be less forgiving, so I like to use the .139"-section sizes. This is assuming you'll keep milling the groove and just want to avoid cutting custom gaskets. Also, you don't need to get as fiddly as a round-bottom groove. A plain round pocket with the same OD as your o-ring and 90-95% as deep as the o-ring is thick should do you just fine.

Conrad Hoffman said:

Use low durometer silicone or similar o-rings. Remember though, you can have the biggest pump in the world and you still only get 14.7 lbs/in^2 pushing the parts together.

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My experience with vacuum chucking using multiple sealing elements is that getting the FIRST "lbs/in^2 pushing the parts together" is the hardest. ;-)

eta

I've used closed cell foam, but again, I have had to make every one of them!