How to choose and use structural adhesives

How to choose and use structural adhesives

Structural adhesives offer many benefits for joining parts together without impairing the look or feel of the finish. There are various types of structural adhesive from which to choose; therefore, knowing which type to use and when is important to ensure a safe and effective result.

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Choosing structural adhesives

Structural adhesives vary significantly according to their strength; in addition, there are other considerations when deciding which adhesive is right for your particular application.

You will need to consider whether the part you are joining will be affected by hot or cold temperatures or will be exposed to water, particularly rain. The sun’s rays can also impact the effectiveness of an adhesive, so you will need to choose a type based on whether the joined part will be exposed to the sun.

Think about whether the joint will come into contact with any other fluids, such as diesel, or whether it will need frequent cleaning with detergents or other chemicals. This will also impact your choice of structural adhesive.

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Special attention must be paid when selecting an adhesive based on whether it will be used for food packaging or medical products. Also, think about whether the bonded joint will be affected by vibrational impacts.

The answers to these questions will help you to make the right choice of structural adhesive for your specific needs. Bear in mind that whether you choose a metal bonding adhesive from a specialist such as or another type of adhesive, it is a good idea to test it first to make sure it is spot-on.

Types and uses

Structural adhesives are categorised according to their chemical make-up, with most consisting of epoxy, urethane, acrylic or cyanoacrylate chemistries. Viscosity can be influenced by the use of thickeners or dilutants, while fatigue resistance can be achieved by adding toughening agents to the adhesive.

Epoxies tend to be used when a really strong bond is needed, especially with metals. Epoxies are used extensively in construction and manufacturing.

Acrylics are often used on plastics, while cyanoacrylates offer good bonding strength on rubber and plastics. Urethanes do not offer the best strength overall; however, they are very flexible and are commonly used on wood, metal and plastic.

Once you have decided which adhesive to use, it is vital that you understand how to handle and process it safely and correctly.