Adhesive Bonding is the process of joining two surfaces together, usually with the creation of a smooth bond. This may involve the use of glue, epoxy, or one of a wide range of plastic agents which bond either through the evaporation of a solvent or through curing via heat, time, or pressure.
Glues have tended to create relatively weak joins but with the use of new self-curing adhesives these bonds are now close to the strength of the materials themselves. As a result, gluing is now the preferred method of joining for many applications, particularly when the bond is not exposed to prolonged heat or weathering.
Many modern glues are carbon-based petrochemical derivatives, which can be used for a variety of joining applications including bonding metal and dissimilar materials. This type of adhesive uses either direct contact or a third surface, such as an adhesive tape, to create the bond.
Among the composite applications that are commonly bonded using adhesives are fibreglass, and fibre-epoxies like boron-epoxy and carbon-epoxy. Due to their shear strength and toughness, modern adhesives can also serve to join structural materials, of which plywood is a common and well-known example.
What are the Advantages of Adhesive Bonding?
One of the main advantages of adhesive bonding is that it allows for the even distribution of stress loads, thereby reducing the stress on the joint. Since they are applied inside the join, adhesives are also invisible within the assembly.
The properties of glues mean that they can form both an adhesive and sealant at the same time, while also resisting vibration and flexing stresses. The ability to act as a seal allows adhesives to help protect a join from corrosion.
While adhesive bonding can be applied to metal-to-metal, plastic, glass, rubber, ceramic and many other material combinations, the process can be used to join irregularly shaped surfaces while offering virtually no change in the dimensions or geometry of the parts.
Adhesives also add very little by way of weight to the materials being joined and can be used to quickly bond dissimilar substrates and heat-sensitive materials.
One of the greatest advantages of adhesive bonding is the versatility it affords, allowing for joining of a wide range of items as well as being easy to automate.
What are the Disadvantages of Adhesive Bonding?
There are, however, a number of limitations to using adhesives. Firstly, they are prone to failure when exposed to high heat or weathering. Adhesives can also take time to fully fix and acquire full strength. They also often require surface preparation treatments including cleaning the surface of the materials to be joined. Other surface treatments associated with adhesives include abrasion to create a stronger bond.
Adhesives can also cause problems related to disassembly when compared to other, less permanent joining techniques.
Where is Adhesive Bonding Used?
Adhesive bonding is used across many industries including automotive, aerospace, medical and even textiles. Due to the versatility of this process for a range of material types the only real limitations arise with use, such as for outdoor applications that need to withstand weathering.
Adhesive Bonding Services
TWI has been at the forefront of adhesives and sealants technology for decades and is now respected internationally as a world leader in both areas.
Find out more about our services in adhesives and sealants