Seeking assembly suggesitons

[groston]

All,

We are a startup company (i.e., limited available cash) that makes a product with a custom molded enclosure. Inside the enclosure is a circuit board with three indicator LEDs, thus we have a clear window in the enclosure, see attached image. The current process for assembling the window is to put a small bead of solvent bond cement on the surface shown and then place the window into the opening. (For reference - the window is 0.50" dia by 0.19" thick.)

This process works and has minimal cost, but it is slow and messy. Can any of you suggest alternative approaches for assembling the window? Note that we do require a good seal between the window and the enclosure as we do plan to have the enclosures certified (ideally to IP67).

Thank you for your assistance!

[JayDub]

groston,

Remember in engineering school when they showed that graph of how the cost of a design change increases exponentially as the project progresses? Well, thank you for a good illustration of why manufacturing should be considered long before design freeze.

A couple of options come to mind. You could over-mold the window. This will probably require a mold change so you can place the window and hold it securely. Whether this will work, and how good a seal you get, depends on the compatibility of the materials involved. Another option would be sonic welding, but for that you need energy directors, which means redesigning the window component, at least. If it is currently a simple disc cut from a sheet, this may be cost prohibitive. Not too bad if it is currently molded though. If these ideas look too drastic, talk to Nordson about optimizing/automating the adhesive application process.

[Suhas]

Totally Agree with JayDub. Overmolding. Actually, it may be easier that you think, not sure.
Suhas

[rickbatey]

Only way to over-mold is if the two parts are of the same resin family plus you'd be handling a clear insert that can be scratched or easily damaged. You could redesign everything and make this a 2K molding process, adjust the design for ultrasonic welding, or even get a used robot to do automated assembly. But you might be better off looking at spin welding or hotplate welding with some design tweaks. Since the window is round, with same resins being used, a spin welder might be fastest method. Have you asked an OEM ultrasonic company to look at the parts? You could buy a new horn and a used machine for a fair price. Of course a Baxter robot is about $30K nowadays.
Rick.

[Qanalyist]

If it works and is cheap are you not in production nirvana? However, there are optically clear resins used to seal LED displays and lights, you could throw away the 'window' and just syringe in some of this gel to fill the hole and let it set. That stuff is designed for this application/ outdoor weather proofing of LED's.