Adhesive replacing rivets or bolts

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Bill-Higdon

Well-Known Member
Joined
Feb 6, 2011
Messages
1,276
Location
Salem, Oregon, USA
3M™ Aerospace AC-130-2 Clear BMS5-162 Type I, Form 2S Spec Surface Pre-Treatment
Skygeek has it in various quantities. I wrote a repair procedure using it and a specific (High Toughness) Scotchweld epoxy for a structural repair 100 feet above the waterline on an aluminum mast on a government asset. The Structural Technical Warrant Holder of the time said "That ought to work, but I'm not putting my PE stamp on your procedure."

In the end, we were not able to use it anyway; the job was in Hawaii and I could not get the prep materials shipped in time to meet the deployment schedule. SO I tripled the already generous bonding area of the doubler plate, and we used the highest grade epoxy we could get on the islands, a product for masonry bonding with a handy static mixer, buffed the crap out of everything with rough Scotchbrite, and prayed. Some kid in a bosun chair did the repair, and I never saw it.

It held for next decade, till we transferred that asset to a Foreign Government and took off the TACAN antenna. I have NO DOUBT it would have eventually failed from corrosion of the substrate at the bond line.

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Would I trust this the BMS5-162 for a garage-level homebuilder? MAYBE. For one thing, the Pre-Treatment is EXPENSIVE. You STILL need a "clean break" surface to start with. But there is enough literature on it's use that I'm fairly positive it would be both structural and durable IF done properly.

Some ideas I've wanted to try -
  • use the MUCH cheaper PreKote (used for paint) as an adhesion promoter.
  • Try the acrylics used for bonding in automotive applications
  • Try moisture cured urethanes like 3M 5200 or the equivalent Sika products
  • Build some lap shear panels and borrow BoKu's "BreakATron"
3M has been pushing Silane treatment for a long time
 
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