Plasma Welding AluminiumPlasma welding is a process that can be used for welding aluminium and aluminium alloys but it is less frequently used than TIG and MIG. The process generally gives high quality welds, normally with very low defect levels, and is usually used on thin sheet or small components. When welding aluminium the process may be used in a similar manner to TIG to create a molten weld pool into which filler metal may be added. It may also be operated to produce a 'keyhole' giving greater penetration and allowing thicknesses of up to about 20mm to be welded. The plasma gas is usually argon and the shielding gas may be argon or helium. Standard TIG filler rods may be used for plasma welding. These are cut lengths of solid wire based on pure Al, Al-Mg or Al-Si compositions. It is normal to try to use a filler material that is as close to the parent material as possible. It is important to be aware that some aluminium alloy compositions tend to crack if welded without filler. Other welding problems that may be encountered when welding aluminium are porosity and solidification or liquation cracking in sensitive alloys. The tenacious surface oxide and all dirt, grease and other contaminants must be removed before. Plasma welding aluminium may present possible electrical and radiation hazards but welding fume generation is normally low, although some ozone may be produced.
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