Five tips for using metal bonding adhesives

Unlike welding, adhesive can be spread over broad areas to distribute loads, and assembly involves no destructive and difficult drilling or heating. They can join dissimilar metals and stand up to heat expansion and mechanical flexing. No wonder car and aircraft manufacturers love them!

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Metal bonding adhesive has some drawbacks, but a few tips will help.

Identify the best adhesive

A host of factors can define the ideal properties of adhesives for particular jobs. If your job requires very high bonding reliability in specialised circumstances, there is a useful guide at http://www.adhesivestoolkit.com/Toolkits/AdhesiveSelector/Introduction.xtp.

Fortunately, there are also products that work for a wide range of applications, like CT1, which is available from sites like http://www.ct1ltd.com/.

Be thorough

Gluing metal is not a quick fix. Welding and soldering are quicker than adhesive when you allow for proper surface preparation and curing time.

Surfaces must be free of dirt, grease and corrosion. Sandpapering can achieve this, but don’t skimp if you want a successful bond..

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Curing times are also important. Although some adhesives bond instantaneously, nearly all gain strength over the following 24 hours. Keep your joint protected by clamping, and avoid jolts, vibrations or temperature extremes until it reaches maximum strength.

Perfect mix

With two-part adhesives like epoxy resins, ideal proportions and effective mixing are vital if the bond is going to live up to the strength and permanence the manufacturer claims. Publicly available products are intended to be easily mixed on a piece of cardboard with a lolly-stick, but professionals weigh the relative ingredients of these products carefully and ensure perfect mixing before they are applied.

Thinning

On some jobs, adhesives work better when they can flow into thread or spread out better between bonded surfaces. Many glues are too thick and gelatinous, but even epoxies can be thinned with acetone, a common ingredient in nail varnish remover and paint thinners.

An alternative method is to apply heat. Warm your tins in a water bath before use. Remember not to put metal tins or tubes in a microwave, and never heat flammable adhesives near a naked flame.

Cleaning

Avoid getting adhesive on your clothes, visible surfaces, or the carpet by preparing your work area and pre-planning how to safely apply adhesive and position your parts.

Vinegar or acetone will clear up most dribbles. On garments, combine it with a hand-hot soapy scrub.