Choosing and Using Structural Adhesives
There are several reasons why structural adhesives are chosen for a wide variety of assembly operations. Unlike mechanical fasteners, they don’t damage substrates by needing drilled holes, and there’s no heat distortion (a risk with welding). They can also join dissimilar materials without galvanic corrosion, work with different geometries, and don’t concentrate stress at a few localized spots, thus increasing fatigue resistance. And after the joining processes, structural adhesives don’t require refinishing steps or leave protrusions, so they are aesthetically more pleasing.
Machine Design Magazine takes a look at the structural adhesives engineers should know about before making design decisions.
Compared to other types of adhesives, structural adhesives have the highest load-bearing capabilities; boast excellent environmental and chemical resistance, with no solvent emissions to deal with; and come with a range of cure times and properties. They cure in an irreversible process which helps provide excellent temperature and solvent resistance. They also do not need access to air to dry or cure, nor moisture like one-part silicone and polyurethane sealants.
In fact, structural adhesives have such a wide range of characteristics that engineers may have difficulty selecting which structural adhesive to use. Compared to other adhesives, however, structural adhesives are less intuitive to use and their performance is widely affected by processing decisions. Here are some tips on choosing structural adhesives and how to handle processing decisions.