Flush retention of a thin disc plaque 1

[IndustDesign]

Hi all,

I'm working on an application that requires a small (1.5mm thick) laser cut aluminium disc (a plaque) to be retained flush within a plastic object (analogy would be if you wanted a fridge magnet to be attached permanently, flush with the door). Whilst disassembly should not be necessary, I'd like to avoid adhesives if at all possible as it will be exposed to liquids (maybe this is irrational though?).

I think fasteners are out because of the flush constraint (laser cut so no countersinking - any fastener head would protrude), I'd thought about a press fit, but given how thin the disc is and the plastic female component, I'm not sure that this would be secure enough.

Any ideas on how this could be done?

Thanks for any help!

 

[zeusfaber]

Unless you want to make expensive changes to the back of your plaque and/or the recess in the plastic part, this sounds like an exercise in selecting the most appropriate combination of adhesive and surface preparation. Deep surface prep with an element of undercut, combined with a generous dose of a resin that penetrates into the gaps before setting - having been selected to wet both materials effectively, to set to be less stiff than either parent material and to be resistant to the liquid in the environment should give you a useful combination of bond and seal.

For volume manufacturing, I wonder if you could make ultrasonic welding work. Probably a bit Gucci for this job.

A.

 

[hydtools]

Investigate inlay methods.

Ted

 

[TugboatEng]

Glue it! An elastomer adhesive will allow for differential thermal expansion between the materials.

 

[IndustDesign]

Thanks all, appreciate your input - sounds like adhesives might be the way to go after all.

Do you think the press/interference fit would fail (I tend to think so?

 

[TugboatEng]

I wouldn't recommend interference fits with materials that have low tensile strengths, creep, or widely different coefficients of thermal expansion.

Polycarbonate, for example, will crack around any press in inserts, eventually.

 

[IRstuff]

3M makes a gazillion varieties of double-sided tape

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[MintJulep]

Do you ***really*** need an aluminum piece?

https://www.weetect.com/screen-printing-on-polycarbonate/

 

[SnTMan]

What I find so rewarding about participating on this site is attempting to answer questions about designs for unknown uses, service conditions, desired life, contractual requirements and so forth such that we can provide a spectrum of advice ranging from "use adhesives" to "screen print it".

I'll add mine: "Wish it into existence".

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[MintJulep]

Human nature.

People start on a path, and run into an obstacle.

The ask for help overcoming the obstacle.

They never step back and ask, "am I on the right path?"

 

[MacGyverS2000]

Multiple sources for aluminum-looking, laser-cut plastics, plastic-coated aluminum, even direct-laserable aluminum sheets (e.g., AlumaMark)... perhaps one of those would work, and you could use everything from tape/glue to ultrasonic welding to keep it in place.

I think you need to revisit your application...

Dan - Owner

http://www.Hi-TecDesigns.com