General notes on welding - AH60.00-P-0005-01N

All models 

General information on welding aluminum: 

Metal electrode inert gas welding (MIG) is the process used most frequently for repairing aluminum. In this process an arc is present between the component to be welded and the wire electrode to be melted. The wire electrode serves as the welding material and transfers the energy required to melt the metal.

The process uses direct current; the electrode is the positive pole.

Welding aluminum requires a great deal of practice and experience. It required steady guidance of the arc and a change in the motion sequences. The welding rate is approximately three to four times higher than with steel. Welding is accomplished at an angle of approx. 75 to 80° from right to left with slight jabbing motion. This allows the welder to clearly see the electrode tip and the welding operation. If held to flat, the heat and protective gas dissipate too highly over the surface. This can lead to faulty welding results.

Preparation of aluminum welding areas: 

Repair welding on aluminum body/body parts cannot be compared with conventional sheet steel weld joints. For this reason it is absolutely  necessary to prepare the welding areas observing extreme cleanliness and to perform a test spot-weld  on a specimen panel (e.g. cut from old damaged part) before performing any welding work on the vehicle or components.

Approved welders are listed under the following link:

Insert gas welder (aluminum)1

Typical welding errors: 

• Fissures  in the weld result, for example, when the welding current is to high or when the wrong wire electrodes are used.

  When repairing cracks, grind out the weld over the length of the fissure down to twice the depth of the crack before rewelding. After rewelding check again for fissures.

• Fissures  in the external paneling can be repaired by first drilling a 2 mm diameter hole at both ends of the crack to prevent further cracking. Then the crack and holes can be welded.
• Pores  in the weld are the fault which occurs most frequently, whereby the tendency to form pores decreases at increasing solidification interval. Pores result from inclusion of gas bubbles during poor cooling. Other causes for pores include:

• instable arc,
• incorrect burner position
• quantity of inert gas too low
• effect of air drafts,
• nozzles too small or clogged by metal spatter.
• contamination in area of weld from grease, oil, paint or dirt

If pores are present, grind out weld and weld over, then check weld seam.

End craters 

Craters are formed at the end of each weld seam, which require filling. This can be accomplished by not switching off the burner immediately at the end of the weld seam. The molten welding wire then fills up the crater.

Cold weld points 

The danger of cold weld points exists at the beginning and end of a seam; this can impair the strength of the connection by notching. For this reason an additional length of approx. 5 mm should be provided at the beginning as well as at the end of the weld.