Using adheasive instead of weld on aluminim

[ewalk]

I am building an aluminum toolbox and would like to eliminate as much weld as possible for cost reasons. Are the adheasives strong enough to use without any machanicial fasteners? Any suggestions on design of the joints?

 

[loughnane]

VHB by 3M.

Shooting from the hip I would recommend you check out the 5915 grade.

Keep in mind if you decide to go this route that VHB is fantastic in shear + tension, but will allow a little bit of flex (but no disengagement) in twist.

Also, if you are doing super high volutmes it might not be cost effective as full curing time will certainly lead to a longer cycle time than welding (even if you accelerate curing with heat).

Call up 3M (or a distributor like Gleicher Manufacturing... they're a great help) and discuss your application.

Chris Loughnane - Product Design

http://www.pdnotebook.com

http://www.twitter.com/DesignNotebook

 

[KENAT]

Rivets?

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(probably not aimed specifically at you)
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[dik]

"Pop Rivets"

POP1, aka Dik

 

[MikeHalloran]

VHB found a home adhering zinc diecast logos and such to painted steel in automobiles. It typically eliminates at least two studs, with corresponding nuts and washers or pushons, and especially the punched holes that accumulate road salt that eventually breaches the paint and holes the panel.

I am aware of a very small sample of such logos that 'just fell off'. Given that the parent population is huge, the bond failure rate may be very low, but it is finite. And the applied load is almost vanishingly small.

I recall repairing or replacing some object having a structural VHB bond not long ago, but I'm not recalling what the object was. I do recall being surprised and disappointed that the object 'just fell apart'.

My oldest toolbox was made for the US Army some time prior to 1960, of thin steel, with some lockseam edges and very little welding. It has been repainted twice and is still in service. Given the quantity of hard steel that's been carried around in it over the decades, I'd have to assert that it has no non-structural parts.

IOW, IMHO, I wouldn't use VHB for a structural application at all, and I'd want to have a backup, like pop rivets or RTV, for a decorative application.

Let's guess for now that your toolbox is currently constructed with folds and corner welds.

To replace the welds with VHB, you have to add flanges to get enough bond area. You have to buy more metal to make the flanges, and worry about another set of tolerances for the bending operations, also added.

You also can't have a U-shaped part bonded on three/six edges, because you can't shear/slide the adhesive face during assembly. The face of the tape has to meet the metal in a normal direction, in the exact location it needs to be, exactly once. Then you have to apply a little pressure, again in the normal direction, to set the bond. That makes assembly of a box more complicated than it would be with, e.g., corner welds.

Given that you have to add operations and flanges to use VHB, it would be little more difficult to use lockseams instead, perhaps with some sealant.


Mike Halloran
Pembroke Pines, FL, USA

 

[KENAT]

Some of the earlier/conservative aerospace use of adhesive also used rivets at least at the ends/corners to prevent pealing.

Posting guidelines faq731-376

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(probably not aimed specifically at you)
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[ewalk]

You guys are great. I have used the VHB for decal plates it is great stuff. Love it...

Is there an adheasive out there that has the peel strength of VHB and the ease of application of a caulk gun?

You can go to

http://www.precisionmetalkraft.com

to view the tool box that I am building.

I am looking outside the "box" for more cost effective reliable methods.

Thanks again you guys are great.

 

[MikeHalloran]

Well, the diamond plate eliminates the lockseam option.

Nice product. No way would I risk its reputation on VHB.



Mike Halloran
Pembroke Pines, FL, USA

 

[ewalk]

Mike,

Thanks for the vote of confidence...I'm and innovator, so finding a newer, better, cheaper, different way of doing things is what I like to do.

Best regards,
ewalk

 

[Ron]

Agree with Mike...stick with welding.

 

[MikeHalloran]

Play with some cardboard models and see if you can end up with a lot of folded edges and just a few welded edges. ... which you can probably do by wasting some material. E.g. making a five-sided box from a cross-shaped blank instead of three rectangles. Use the waste corners to make dividers or accessory trays or something else.

I'm tempted to suggest automating the welding, but I'm aware of an ancient effort to do so that required milling the blanks in order to make them weld at a consistent speed (whereas a welding person compensates automatically).





Mike Halloran
Pembroke Pines, FL, USA

 

[loughnane]

It's a good point on the difficulty of using flanges + VHB together, especially considering the fact that it is a PSA. That alone writes it off, but don't be dissuaded for structural apps... I've used it bonding plastic to sheetmetal in an app where it's seeing some serious loads, and it's held up great.

Not to mention the mirror panels @ chicago o'hare... 23 years and counting.

Chris Loughnane - Product Design

http://www.pdnotebook.com

http://www.twitter.com/DesignNotebook