FromRubber Custom Injection Molded Plastic Seals for Night Vision Device

A night vision device is a closed optical housing, and every seal inside it does more than keep dust out. Light that leaks past a tube mount or an eyepiece gasket shows up as veiling glare on the image, and a gap that passes moisture fogs the optics from the inside, where nothing can be cleaned. That is why the seals on this kind of device are usually custom molded plastic seals rather than cut foam or rubber strip.

We mould them as thin-wall plastic seals and retaining rings in ABS, PC, PP or nylon. The polymer follows the duty: PC and ABS where the part also clamps or locates a tube, PP where a soft flexing lip is wanted, nylon where the part is thin, threaded or takes a screw. Wall sections are kept uniform so the part does not sink or bow, and the mating faces are held flat enough that the seal closes on a full face instead of on one high point.

Two details decide whether the part works. The first is the flash line: it is placed on a non-mating face, because a witness line across a light-tight joint opens a path for both light and moisture. The second is orientation: where a seal is not symmetrical, the locating tab or keyway is moulded in, so the part cannot be fitted reversed on the assembly line.

For a quotation, send the mating housing or its drawing, the gap the seal has to close, the surface finish required on the optical faces, the polymer you have in mind and the annual volume. Where the housing already exists, we can scan the cavity and work from measured geometry instead of a nominal drawing.

Tooling, moulding and inspection run in our own plant, so a change to a seal face or to the blackout finish is handled by the same team that cut the tool, and a moulded plastic seal can be re-cut without re-sourcing the whole assembly.