Glue/adhesive instead of welding

Steel and aluminum boatbuilding. See: "Boatbuilding Methods", in left-hand column of the Home page, for information about alloys.

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cac
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Location: Stockbridge, GA
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Glue/adhesive instead of welding

Post by cac » Tue Apr 17, 2007 7:38 pm

Any thoughts on the practicality of the new adhesives taking over some/all the welding on metal boats?

Lots of the industrial world are using various glues and adhesives for things like trailers, truck cabs, truck bodies, etc. Looks like if it could hold up in over the road use, then we're getting close.

Being able to join stringers to the hull or whatever with a glue gun could open up a lot of metal building for those of us who don't weld or are not confident in our welding.

Thoughts?

A couple of articles:

http://209.85.165.104/search?q=cache:QH ... =firefox-a
http://news.thomasnet.com/fullstory/471884
Check out Craft a Craft - Boat design, home building, and cruising in a nutshell
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gregggrundon
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Location: Kwajalein

Bonding vs. welding

Post by gregggrundon » Sun Jun 10, 2007 2:57 pm

Cac,

Have you contacted Locktite to ask what they think of marine applications?
I like the idea if it woould hold up.

Gregg
Jolly Roger 30'(Extended)
Marshall Islands, R. M. I.

canadianwelder
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Location: Vancouver, Canada

Post by canadianwelder » Wed Jul 25, 2007 7:19 pm

When you consider the forces placed on a boat, full fusion of all joints would be crucial to the integrity of the structure.

Kevin Morin
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Re: Glue/adhesive instead of welding

Post by Kevin Morin » Thu Sep 04, 2014 2:58 pm

Older Metal Thread bumped to offer some clarifications and impressions.

Metal frames that are glued or not welded would probably react differently in three or four important ways compared to the welding or full fusion of those elements.

Aluminum is pretty thermally reactive and so the expansion and contraction of the frame pieces compared to the sheeting materials may tear at the interface of glue/tape/adhesive to metal. Even in Southern lattitudes water temp is not exactly air temp. so launching a metal boat with adhesives instead of welded joints seems like it would introduce some large stress to the glue joint?

A welded joint will by the nature of the melted then solid metal react to temperature the same way as the rest of the structure or skin/hull panels. So this seems a pretty significant difference when discussing the idea of a glue/calk/adhesive joining of metal?

Shock is the term for impact (resistance) or exposure to impacts- so shock loads to flexible joints is not the same as it is to more rigid (welded) joints. So a joint that was structural or even skin-to-frame seems like it would have some absorption of impact energy in the softer adhesive but that also seems like it would work to limit the bond between the metal's being adhered by the goop/tape/calk/glue?

Ultimate yield or tearing apart. Steel is pretty tough to tear apart, aluminum is too but not as tough as steel, however both seem like they'd be a long way tougher than tapes/glues/adhesives and similar chemicals? So the implication of a glued together boat frame is the joint would have to be designed so much larger in area and heavier in cross section to allow a limited yield material to be part of the stronger materials like steel or aluminum. IF the glue's yield were half of the metal the joint would have to twice the size of the original to compensate for that limit in yield.

Wood glues, especially the epoxy group of glues, meet or beat the underlying material's yield strength.
That implies that an adhesive applied to wood is not a reasonable comparison to metals joined with glues because of the difference in the bond to the two types of materials.

3M offers a series of products that are used to bond aluminum panels to welded trailer frames, and they seem to perform well? On the other hand those trailer frames (box utility trailers) all seem to have welded main frame elements?

I'm first to agree that welding aluminum (especially) is expensive and the skill set is mainly acquired by lots and lots of practice with this expensive system with expensive consumables of argon and wire. So I agree that it is appealing to look at newer 'space age' modern chemical products to joint metal boats allowing the work to be done with less expensive joining methods; my take on the physics of the potential joints and seams is that there is no chemical 'miracles' on the horizon to make this realistic.

There is no simple, cheap, fast way to overcome the welding hurtle in a metal boat but welding is like any other skill; with time and practice anyone can learn to do the work. As someone in debt for years to afford the power supplies and equipment needed I can also understand the burden of the expense and the difficulty of justifying such a large cost if you're only using these specialized tools once in a blue moon.

But on the other hand I'm not aware of anything in the market place that will allow anyone to build a one-off metal boat except for welding. Maybe the current generation of adhesives, tapes and glues will become a substitute in time, but for now I'm not aware they could do the whole job?

I know we hear stories of 'jet fighter wings' made with glue(s) but I'm not sure the underlying frame of that wing skin is glued together?

Cheers,
Kevin Morin
Kenai, Ak
Kevin Morin

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