BONDING
There are many adhesives recommended for bonding aluminium
Araldite 2015 is a good choice of adhesive as it approved
for use in the marine industry however other glues may be used depending upon
the application.
A glued strip 25mm wide and 1m in length with a high-quality bond (17N/mm²)
will carry 52 tonnes in shear force (7 African elephants!).
It can be seen that there is plenty of safety margin if your glued joint isn't perfect. For safety-critical applications, the addition of
mechanical fasteners such as rivets is recommended. I would also recommend performing a "water break test" to prepare surfaces prior to bonding to ensure you have a clean surface.
BONDING ADVICE
FROM HUNTSMAN FOR ARALDITE 2015
The ideal thickness for 2015 adhesive is between 0.1 and 0.5 mm. so 0.25 mm is perfect.
Bonding on anodized surface is highly recommenced, as well as a roughened surface (sand paper/ sandblasting/ etc..). degreasing is
also important and you can use isopropanol or acetone (never use surfactant).
SUBSTRATE PREPARATION
In order to obtain the optimal adhesion on both substrates, it is highly
recommended to prepare the substrates before bonding. In most cases, abrading
the substrate (for example with sand paper) and degreasing by wiping with a
solvent like acetone, ethanol or isopropanol will help to increase the
durability of the bonded assembly.
Substrate abrasion /
Roughness
The ideal roughness to bond metal substrate is 3 < Ra (micrometer)
< 5.
ESSENTIALS FOR
MAXIMUM BOND STRENGTH
Araldite® adhesives are simple to use, but to ensure
successful bonding the directions given in the instructions supplied with the
adhesive must be strictly observed.
In particular:
1.- Resin and hardener must be correctly proportioned
and thoroughly mixed together.
2.- Joint surfaces must be degreased and, when
necessary, pre-treated.
3.- Curing temperature and curing time must be
correct.
4.- Jigs or other fixtures must be used to
prevent the bond surfaces from moving relative to one another during the curing
process.
5.- Though only light pressure is needed, it
should be applied as evenly as possible over the whole bond area. Excessive pressure
leaves the joint starved of adhesive. In laboratory conditions, the pressure
applied is generally 30 – 50 N for a bonding area of 312.5 mm2. This figure may
be adjusted when using products with high viscosity.
Further aluminium bonding advice
http://www.henkelna.com/us/content_data/213261_LT3371_Metal_Bonding_Guide_022011_LR451580.pdf
http://www.aluminiumdesign.net/design-support/joining-aluminium/#toc-adhesive-bonding | 