smart51
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| posted on 10/8/09 at 03:13 PM |
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what adhesive for aluminum and MDF?
I want to laminate a sheet of aluminium to a sheet of MDF. I want a non-brittle adhesive that can cover the whole surface without giving air bubbles
and can be squeezed out to remove excess. I don't want the two to ever peel apart.
My first thought is PU adhesive only it is to thick to cover a 300 x 350 mm panel. Epoxy can be a bit brittle and silicone is not adhesive enough.
A liquid PU would be great. Any ideas?
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twybrow
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| posted on 10/8/09 at 03:23 PM |
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What surface prep are you doing on the Ali, as ali will oxoidse over time, and your bond may fail. Normally this is solved by doing a surface
treatment on the ali prior to bonding...
So this is a structural load bearing bond then?
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smart51
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| posted on 10/8/09 at 03:29 PM |
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It is for a speaker baffle. Not exactly load bearing but subject to a lot of vibration. I want something very thin but stiff and acoustically dead.
MDF is dead but not stiff and as I only have 50mm of height I can't use a thick piece. Aluminium is (relatively) stiff and also acoustically
dead and is the new wonder material in acoustic circles. A laminate of the the two is just what I need.
Surface prep of the face to be adhered will just be panel wipe. The aluminium comes with a peel film on it so shouldn't be oily. Won't a
good adhesive keep out moisture so prevent corrosion?
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Richard Quinn
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| posted on 10/8/09 at 03:35 PM |
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Epoxy isn't brittle. I used to make racing model powerboats with very lightweight deck mouldings (1 layer of 200gsm cloth) and you could pretty
much bend them in half lengthwise.
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twybrow
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| posted on 10/8/09 at 03:40 PM |
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Sod the MDF/Ali, just make it all out of GRP! throw in some carbon, and a thin core and you will have a very stiff, very light structure, that is
accousticaly very good at damping!
A solvent wipe is not surface prep - that is just a degrease. I am talking acid etch, vapour blasting, primers etc. Epoxy would do that just fine -
how much vibration does an aircraft/car suffer from, and can be made using epoxies. Why not back the epoxy up with a few mechanical fasterners
(rivets) to help with the bond?
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Madinventions
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| posted on 10/8/09 at 04:01 PM |
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I did exactly the same thing for some speaker cabs for a customer some time ago and just used good old EvoStick! Don't get the gloopy stuff in
a tin, go for the aerosol version and make sure you've got a hard rubber roller handy.
Spray both materials with contact adhesive and wait for it to go tacky. Then just start to stick the two pieces together starting from one edge. Use
the roller to make sure there aren't any air bubbles. Wait for it all to set, then go around the edge and trim off the excess.
I did this to a whole 8' x 4' sheet before cutting it into sections on my table saw. You may need a few extra hands and arms to help you
though if you do it this way!
Ed.
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MikeRJ
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| posted on 10/8/09 at 04:40 PM |
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A contact adhesive (such as Evostick) is perfect for this kind of application. Smells lovely too
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smart51
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| posted on 10/8/09 at 07:53 PM |
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OK, here's an odd ball thought. I've got loads of gelcoat and polyester resin. If I abrade the aluminium up a lot will that make a good
bond?
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twybrow
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| posted on 11/8/09 at 09:18 AM |
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That should help with the bond. Abrade then clean and degrease.
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