Traditionally, metals have been joined either with mechanical fixings, rivets and bolts or with heat methods, welding, brazing and soldering. In recent years, however, there’s been a shift towards the use of glues.
It’s easy to understand why using metal bonding adhesive is an attractive technique. Compared to heat bonding techniques the use of adhesive reduces the chance of distortion and discolouration. They also make it easier to join metals that have different melting points and they make for more even distribution of stress loads.
Adhesives form a seal in addition to a bond, so they can help to protect joints from corrosion and moisture ingress. They make it easier to join irregular shapes too. No wonder the market is expanding – http://menafn.com/1095292692/Structural-Adhesives-Market-size-is-expected-to-increase-USD-183-billion-by-the-end-of-2022.
Types of adhesive
Adhesives used to bond metal fall into two categories. Structural adhesives are used to bond components together and are the main means of supporting a load. Machinery adhesives are used to supplement a mechanical bond to augment the seal or holding force. Examples of the latter would be things like adhesives used to lock screw threads to ensure they don’t work loose.
When buying adhesives from a supplier like http://www.ct1ltd.com/ you’ll find there are generally four different technologies. These are two-part acrylics in both mix and no-mix forms, epoxies and polyurethanes.
Cyanoacrylates, silicones and light cure acrylics are sometimes used too, but they tend to be for specific applications and they’re less suited to harsh environments than the other types.
Each type of adhesive has its own properties in terms of curing times, strength and durability. It is, therefore, important to assess the needs of a particular project and choose the most suitable type for the job.
Preparation
With adhesive as with any type of bonding, preparation is a key element of success. All surface contaminants like oil and grease need to be removed as well as rust or oxidation of the metal. With the surfaces clean it’s possible to form a strong bond that will last for many years without risk of failure.
Assemblies need to be tested at the design stage of the project to ensure the correct choice of adhesive both for the materials used and the use of the finished assembly. The environment in which the finished project will be used is a key consideration too.
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