As they are intensively used, commercial vehicles can accidentally be damaged, and need to be repaired. This usually includes a welding operation, which is today as easy for aluminium vehicles than it is for others, thanks to ever increasing performance and efficiency of aluminium welding equipment.
Aluminium Welding Procedures
Like other metals, aluminium should be welded according to a strict procedure, in a properly equipped workshop, by a qualified operator, and when required, under the supervision of an official body.
Aluminium Welding Processes
Main welding processes used to repair aluminium vehicles are TIG and MIG arc welding. Other techniques like laser welding and resistance welding are also in progress, but they should, in first instance, penetrate the manufacturers market.
The following section describes the typical weld repairs operations.
Nothing should be done before knowing the type of goods that the vehicle has transported!
Once determined, appropriate precautions should be taken (e.g. degassing, dust removal, etc…).
Choice of alloy
The alloy of the semi-finished product (e.g. patch) used for the repair must be the same or compatible with the original alloys (see manufacturer’s manual).
This comment is also valid for the filler wire that might be used during welding.
• For cutting out, cutting wheel in carbide is preferred, rather than high-speed steel (HSS) or abrasive wheels that might introduce inclusions into the weld seam.
• Grind the area to be welded to remove all traces of paints and other residues.
• Degrease the surface prior to welding (using baltane or equivalent solvent).
Selection of Welding Process
As it allows better penetration, TIG is usually preferred for minor repairs where access from behind is not possible.
When fast welding is required (e.g. to control deformation, or because of long welds), preference should be given to MIG.
The choice will also depend on the thickness of the parts to be welded.
• Change the path of welds in order to avoid going over an original weld
• For minor repairs, the patch must match to the shape of the breach, but, to avoid cracking, it should be slightly enlarged by hammering to compensate for contraction following welding.