Types of metal bonding adhesive

There are many types of metal bonding adhesives available depending on the application required. What is the material you intend to bond? Do you need it to support a heavy load? These are considerations when choosing the ideal adhesive.

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Context

Metal bonding has changed considerably. Historically, metal was bonded together using methods such as welding, soldering and brazing. These had many problems associated with them, such as discolouration, distortion and weld worms. Surfaces had to be drilled in preparation, which was time consuming, and load bearing was not equally distributed. The creation of adhesives has eradicated these problems.

Classification

Adhesives can broadly be separated into two categories: structural and non-structural. Structural are designed for heavy loads, whereas non-structural are most often used for augmenting seals. Adhesives come in many states, including liquid, paste and granules. They can also be in tape form.

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Benefits of adhesives

When choosing an adhesive, it is important to consider the application and how it will perform. There are benefits of using a metal bonding adhesive such as http://www.ct1ltd.com/product-applications/metal-to-metal-adhesive/. Some of these are that two materials with differing melting points can be bonded; the stress load has more even distribution, reducing stress on the join; adhesives form a seal in addition to a bond, which protects it from corrosion; and two irregularly-shaped items can be bonded together more easily.

Structural adhesives

Heat and chemical resistance are significant considerations for metal bonding. If the substrates have differing thermal expansion coefficients and are cooled and heated often, the bond may become weakened. For aluminium and steel that form an oxide layer, moisture prevention is necessary. The following adhesives can offer a high-strength bond with resilience in harsh environments: two-part no-mix acrylics; two-part epoxies; two-part mix acrylics; and polyurethanes. There are shortcomings with all these options, such as slow curing or reduced efficacy at lower temperatures in the case of polyurethanes. The substrates and application must be carefully considered before choosing.

Machinery adhesives

These adhesives are used for applications such as thread-locking, cylindrical assemblies and sealing between flanges. It is in liquid form until application, at which point – when exposed to oxygen – it cures rapidly to form a tough adhesive with little flexibility. As a liquid, it covers all surfaces easily and helps to prevent corrosion. These qualities make anaerobic adhesives ideal for use with machinery.