Adhesive bonding (also referred to as gluing) is a joining technique to join materials by applying an intermediate layer of adhesives or glues. This joining technique involves glues, epoxies, or various plastic agents that bond by evaporation of a solvent or by curing a bonding agent with heat, pressure, or time. Adhesive bonding is similar to soldering and brazing of metals in that a metallurgical bond does not take place though the surfaces being joined may be heated but they are not melted.
Many of adhesive bonding materials make superior stress-bearing components. Adhesives distribute stress load evenly over a broad area, reducing stress on the joint. As adhesives are applied inside the joint, they provide smooth surface appearance. Adhesive also form a seal as well as a bond, which can help protect a joint from corrosion. Adhesives can easily join irregularly shaped surfaces, or dissimilar materials at low processing temperature with very little weight to the materials being joined.
Adhesives often require surface preparation treatments including cleaning the surface of the materials to be joined. Oil and grease on the surface seriously lower the surface energy of the metal surfaces and thus impair the bonding strength. The amount of time required for fixture and full strength is also one of the limitations of adhesives.
Very often Adhesive bonding is applied in combination with resistance welding and mechanical joining in a Hybrid joining process.