Need help sourcing a custom-made Buna O-ring.

[MechEngineer2012]

I am looking to have a custom-made O-ring produced with tight tolerances. The required cross-section diameter is 0.139" ± 0.004". can you see the attached drawing and advise on the most cost-effective manufacturing method for this O-ring.

 

[dgeesaman]

 dgeesaman - "That photo feels implausible to me, especiall with the groove depth barely reaching the centerline of the o-ring body"

I am on the fence over whether I should post a more complete photo of the example I offered to counter your skeptical remark but the full geometry is part of a proprietary design, so no. The small section of the seal geometry I show works for a device that must maintain a seal with exposure to biological fluids at 300 psi and compatible with autoclave sterilization, and compatible with exposure to laboratory disinfectant solutions. Does this work for 3000 psi hydraulic systems? No. As I stated, the the OP has not said what is their sealing conditions and environment only they need an o-ring with 'tight tolerances'.

I hope it didn't sound like I'm accusing you of doctoring that photograph, because I'm not.

But it's still true that my experience with contouring o-rings into standard rectangular-section grooves / non-circular groove paths has me fully expecting that o-ring to pop out.

There is likely some important detail difference here that I haven't observed that makes it possible and predictable.

 

[Brian Malone]

dgeesman - thanks, all good! The guidance given by the posts that explain sizing the o-ring to avoid/minimize putting it in compression within the groove perimeter is what helps make the seal less prone to pop out. Zero response from the OP, so hopefully they have gleaned a little guidance and have their design progressing.