Adhesive bonding

Adhesive bonding is the joining together of two metals or a metal and a non-metal using a thin layer of adhesive. The strength of the adhesive bond is determined by the bond strength between the adhesive and the material to be bonded (adhesion) and the mechanical strength of the adhesive itself (cohesion).

Adhesive bonding of aluminium-based materials uses a thin layer of an adhesive to produce a joint with other metals or non-metals. Suitable adhesives are usually liquid plastics that form a joint with the surface of the workpiece either by supplying heat or, at room temperature, by addition of a hardener.

The strength of the glued joint is determined by the strength of the bond between the adhesive and the material being bonded (adhesion) and the mechanical strength of the adhesive (cohesion). As the strength is lower than that of the metals, the bonded area has to be correspondingly larger. The glued joint should be designed in such a way that the forces to be transmitted only act in the direction of the plane of adhesive bonding.

Adhesives that achieve good adhesion on metals and show good strength and durability are called structural adhesives. They are mainly macromolecular duroplastics (synthetic resins). Adhesives do not usually attack aluminium.

Adhesively bonded joints are two-dimensional with completely sealed glued joints. This means that compared with srewed, riveted and welded joitns the load transmission is more uniform without any stress peaks at the edges of holes or other points and thus to better fatigue resistance as well as a crevice free, liquid-tight joint without the need for additional sealing measures. There is no need for insulation measures when joints are made with other metals.