Because active metal.
Glue to attach aluminum to aluminum.
A good water washing should do the trick.
Cyanoacrylate also known as instant adhesives super glue crazy glue ca glue etc.
The sanded area will help the glue adhere better to the metal.
Most epoxy metal glues for homeowners tell you to assemble the parts within a minute or two of applying the adhesive.
For most everyday situations and simple diy projects a liquid adhesive or glue for metal is the best solution.
Metal to metal epoxy glues typically instruct users to clamp the parts together for the first 30 to 60 minutes while the adhesive sets but to wait up to 24 hours before putting the glued.
If the aluminum needs to be scrubbed to get it really clean use 00 or 000 grade steel wool to do the job.
Everyone who works with metal from metal workers and mechanics to jewelers and hobbyists knows gluing metal needs good preparation.
All grades will bond aluminum well.
These aluminum adhesives are ideal as sealants retainers and fip gaskets.
Short ish video comparing how well or poorly four different common adhesives bond aluminum to wood specifically maple.
Wash the side of the aluminum which is to be bonded thoroughly with a mild soap and water to remove dirt and oil.
This glue is best for gluing very small pieces of flat aluminum or gluing small pieces of other material to aluminum.
Bonus content at the end of the vi.
Anaerobic cure mechanism anaerobic adhesives cure in the presence of metal and absence of oxygen.
Sand the area that is to be glued.
For bonding aluminum to dissimilar surfaces with different coefficients of thermal expansion consider toughened 737.
Dry the pieces of aluminum with a rag.
Preparing the aluminum for gluing.
Hot glue with thin lightweight aluminum you can glue the metal using hot glue provided that the metal has a few holes drilled in it through which the melted glue can flow then harden.
For very high strength use a metal bonder such as 170 or the original 910.
The oil if left on the aluminum will interfere with the bonding process.
Waiting too long will ruin the bond.
Metal glue is a great way to join metal to metal or metal to other materials.