There are several things to be aware of when gluing aluminum to a surface. Small aspects such as the cleanliness of the surface being glued and the pressure applied to the contact points can help to provide strength to a weld that it might not otherwise have. The type of adhesive also can make a huge difference in the type of bond that is established with the aluminum. Important design aspects can determine exactly how to glue aluminum, if it should be done at all. Thinking about the amount of stress that will be applied to the glued area can be vital before starting to perform any type of gluing, because this also can help guide the tools and procedures that need to be used.
Successfully gluing aluminum begins by preparing the surface. This step is sometimes skipped, but it can make a massive difference in the end. The surface needs to be absolutely clean and free from any dirt, debris or oils. Once cleaned, it is important to understand that an aluminum surface oxidizes within one hour after having contact with air, creating a type of skin on the surface that is not good for adhesives. This means the surface to be glued needs to be sanded until the non-oxidized aluminum is revealed, and the bond needs to be made within one hour to prevent the oxidization from occurring again.
The overall design that requires gluing aluminum should be considered. The area of contact where the gluing will occur should be flat and have enough surface area to allow enough of the adhesive to create the bond. In instances that call for gluing aluminum to curved surfaces, or surfaces that are very rough or irregular, alternative methods of attaching the pieces should be explored.
When selecting the adhesive, consider the type of project involved. For nonporous bonds, such as aluminum to metal or glass, one good choice is an epoxy resin. When gluing aluminum to wood, polyurethane glue might work the best, because epoxy tends to have difficulty with porous surfaces. Flexible or temporary bonds can be achieved with silicon glues.
Whatever the choice of glue is, it is vital to follow all of the manufacturer’s instructions and use only the amount necessary. Gluing aluminum usually requires relatively expensive products, and using too much of one is more likely to waste expensive adhesive than to strengthen the bond. Safety warnings about toxic fumes or corrosive effects need to be followed exactly. Another tip when actually gluing is to make sure the pieces being joined are not clamped too tightly together because, unlike other types of glues, epoxies and polyurethane adhesives work best with only firm contact, not crushing pressure.