Dave Fawthrop wrote:
On Sun, 01 Apr 2007 18:35:22 +0100, Alex Coleman wrote:

|!On my rather old tube of 'regular' Araldite it says it is ok for metal.
|!
|!If this is so then why would I ever use one of those 2-part adhesives
|!sold specially for metal? I mean the sort of thing that is usually
|!coloured grey and can often be bought in car accessory shops?
|!
|!I need to glue an aluminium ring (about 1.5 inches diameter and about
|!4mm thick) to a plastic base. There will be some light to moderate
|!stressing of this arrangement when it is in use.
|!
|!I figured the Araldite was just fine for the plastic but what about the
|!metal?

Yes! But!
Everything needs to be *real* flat, *real* smooth, and *real* clean, and
not have release agent on it, also both bits need to be rigid. We used to
do it for aircraft components. So if you can do the first two bits within a
few thou (you can measure to 1/10mm can't you), degrease the aluminium and
roughen up the plastic with fine emery and degrease, to get rid any release
agent, get some *new* araldite, then it *may* work, otherwise give up the
idea of araldite.

But wouldn't the aluminium be anodised and epoxy primered first? That's
the way that I remember in the aerospace industry. The paint had a much
higher bond to the metal than the 'Hysol'* had to the paint and the
bond was very impressive.


*Hysol is a variant of Araldite and much better all round. It could be
used as an adhesive when mixed in the two parts, or used as a liquid
shim, when various fillers were added, that removed the need for
accurate flatness / surface conformity.

Dave