Why You Should Avoid Welding Anodised Aluminium

Industrial & Manufacturing Blog

Anodising refers to the process by which a metal is placed in a chemical bath so that it forms an oxide coating on its surface. For instance, aluminium will form a dark-coloured coating of aluminium oxide. That coating is porous and can be dyed easily. However, anodising makes it hard to weld the metal. This article discusses why metal fabrication hobbyists should not try to weld car components made from anodised aluminium.

Electrical Insulation

One of the biggest reasons why hobbyists should not try to weld anodised aluminium is that the coating on its surface (aluminium oxide) is a poor conductor of electricity. Consequently, it will become very hard for your basic welding equipment to form an electrical arc that can weld the metal successfully.

Elevated Melting Point

The welding process entails directing intense heat towards the metal that you wish to weld. That heat melts parts of that metal so that a weld joint is formed from the fusion between the metal component and the filler wire. Aluminium usually melts at a temperature of 1,218 degrees Fahrenheit. However, the aluminium oxide coating on the surface of the metal has a much higher melting point of 3,762 degrees Fahrenheit. That coating triples the amount of heat that will be needed to weld the anodised aluminium metal. Such a high temperature may be hard to achieve with your basic welding equipment.

Furthermore, the coating on the metal will form a gummy puddle on the weld joint if you succeed in attaining the high temperature needed to weld through the aluminium oxide coating. That puddle will make your car component visually unappealing.

Increased Surface Porosity

As already mentioned, the aluminium oxide coating on the surface of the sheet of metal is very porous. Consequently, the coating will keep absorbing vapour or moisture from the air during the welding process. That water will keep being released as the weld seam cools. The released water will leave microscopic holes that will make the welded part extremely porous.

As you can see, it may be hard for you to get satisfactory results when you attempt to weld car parts that you are fabricating from anodised aluminium. Consequently, you have two options to choose from if you wish to have parts from andised aluminium. First, you may have to use a sanding tool to remove the coating from the metal before you weld it. You can then ask a professional fabricator to anodise the component afresh. Secondly, you can ask an expert fabricator to use specialised equipment to weld the anodised aluminium component for you. Pick the option that is easier for you to implement. Contact a metal fabricator for more information.


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