Fast fixture time for structural adhesive?

[proth]

I am looking for an adhesive to bond two pieces of stainless steel sheet metal together. It is a vertical joint with a 0.5" x 0.5" bond area. The "hanging" component weighs 0.01 pounds.

I need a structural adhesive that can hold the 0.01 pounds almost instantly (within 5-6 seconds). Once it is applied and can hold the 0.01 pound component in place it will then be subject to 5 minutes at 250 deg F.

My biggest goal is to avoid any sort of clamping.

 

[IRstuff]

Crazy glue? or the gel form thereof?



TTFN

 

[proth]

I need to apply this to 2,000,000 parts and the cyanoacrylates are not withstanding our humidity/cold cycle testing. We have had a little luck with strutural acrylics and are testing a few epoxies but the fixture time is very slow.

 

[IRstuff]

And what other requirements are there? Vibration? What temps, what humidity?

TTFN

 

[proth]

1) zero vibration
2) 95 deg F/95% humidity
3) -35 deg F cold

 

[IRstuff]

Have you tried hot glues:

http://www.glu-stix.com/shop/page/product_detail/Product/02aca1e2478d7530bd5a60c6b099276f.html

http://www.glu-stix.com/shop/page/product_detail/Product/67136cccf00d511637cd2e7ece2b38b7.html

http://www.glu-stix.com/shop/page/product_detail/Product/5c5f7517b30add4c70eb3cd776a69d91.html

TTFN

 

[proth]

Thank you for your comments and ideas! This has been a particularly tough application for us so I appreciate your patience and creativity.

Would the hot melt be strong enough? To give you a better idea of the design there would be a 100 lbs of force being applied in shear to the 0.5" x 0.5" bond area. There is a slight peel requirement as well. We have found that an acrylic with 3400 psi shear combined with 23 pli peel has worked very well but we're back to the fixture time issue.

 

[unclesyd]

Here a company that has provided some different approaches to several tricky bonding problems.

http://www.jodantech.com/default.asp

Way out of the box.
These people make some unique adhesives.

http://www.parkell.com/

 

[IRstuff]

Your problem continues to be very misleading. Your original statement that the hang weight was 0.01 pounds was a complete red herring, since the actual requirement is to sustain a 100 pound shear.

I suggest that you spot weld. It's fast and it'll be strong enough to meet your known requirements.

TTFN

 

[MadMango]

Give Sika a call, they should have exactly what you are looking for. You could also try 3M's VBH tape a shot.

[green]"Art without engineering is dreaming; Engineering without art is calculating."[/green]
Steven K. Roberts, Technomad
Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[proth]

Thank you for your replies!

We are looking to replace spot welding. It needs to only hold 0.01 lbs within 5-6 seconds. Once the adhesive is cured (many of the adhesives I have found have a 24 hour cure time) it will then be subjected to the load and atmosphere I reference above.

 

[IRstuff]

OK, let's back up.

Tell us what you've tried that does work, excluding cure time.

TTFN

 

[Compositepro]

Other alternatives to consider are using a pressure sensitve adhesive like double sided tape or hot-melt for instant fixturing and a second setting adhesive for strength, or something like a urethane hot-melt that then crosslinks by reacting with moisture. Although spotwelding sounds easiest and most robust.

 

[MikeHalloran]

A lot of otherwise magical adhesives are not magical at all at -35F.

The adhesive you seek is commonly called a Pop Rivet.



Mike Halloran
Pembroke Pines, FL, USA

 

[proth]

We have only been able to find one product to work and that is a two part acrylic from 3M. We have tried Devcon and Loctite products but they have failed up to this point. The adhesives typically fail the humidity testing where we cycle between -35 deg F and 95/95 humidity for 5 days. Each day the parts spend 8 hours at -35 deg F and the rest of the day at 95/95. This is then repeated for 5 days. Most adhesives fail after day 1.

 

[ScottyUK]

Your bond area is quite generous. Have you consulted the manufacturer for surface preparation requirements? Some adhesives can lose a large amount of strength if the bond surface conditions are not 'just right'.

Have you tried Dow Corning? Some of the silicone family of adhesives has remarkably good mechanical properties, especially in relatively thin film applications between two relatively rigid substrates. They're available with rapid thermal curing. I don't have the p/n's of the materials we used to use in the hybrid electronics industry, but these materials were qualified for the full military temperature range. We used a screen printable material as well as automated luer-lock syringe dispensers, both of which might be well suited to your high volume.

----------------------------------

Sometimes I only open my mouth to swap feet...

 

[Ron]

Hey Mike...thought I'd try marketing your idea...couldn't get those little suckers to come out the end of the tube <g>

 

[MikeHalloran]

You just need a stronger tube squeezer...


Mike Halloran
Pembroke Pines, FL, USA

 

[unclesyd]

You might want to give these people a call. It looks like some of their transfer adhesives might work.

http://www.scapana.com/index.jsp