This was to investigate if 3D printed O rings can provide an effective high pressure seal. The answer is YES if using a suitable flex filament.

Samples were printed using 2 filaments, Recreus Filaflex Shore 82A and Esun TPU Shore 95A, and aluminium alloy parts made to test them at high pressure as both a face seal and a radial seal. Seal groove dimensions were as from Dowty Seals catalogue.

The radial seal set-up was leak tight with the Filaflex 82A seals at 80 bar (1200 psi) for several hours. The Shore 95A seals were too stiff to fit / remove easily so unsuitable as a radial seal and weren't tested.

The face seal set-up was leak tight with both materials, again at 80 bar for several hours in each case. All at a cool temperature - about 10 deg C.

Elastomer O rings are most commonly Shore 70A, but can be up to Shore 90A. So the Filaflex 82A is within the normal hardness range and I think entirely suitable for lowish temperature (up to about 60 deg C?) applications. For larger section seals at least, it should be possible to produce a 'softer' seal by adjusting the infill density (my samples were 100%), but I haven't tried this.

If anyone thinks they have real world use for this I would be most interested to hear from you. Elastomer seals are cheap enough, but typically there is a minimum order price or quantity, so for maybe for one-off repairs, prototypes or non-standard sizes (in non safety-critical applications!) there may be a use.

The attached Fusion 360 file has 2 variable parameters; the O ring inner diameter and the cross section diameter. The section isn't actually circular, but has a flat and 45 degree angles on one side to give a clean print with no support material.