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

Model 215 

General information on welding aluminum: 

Metal inert gas welding (MIG) is the procedure used most frequently for repair welds on aluminum. With this process, the arc burns between the component to be welded and the melting wire electrode. It serves as auxiliary material and transfers the energy required to melt the metal.

Welding is accomplished using direct current, the electrode is the positive pole.

Welding aluminum requires a high degree of practice and experience. It requires smooth guidance of the torch and a different motion sequence. The welding speed is approx. three to four times higher than with steel.

Welding is accomplished from right to left at an angle of approx. 75-80° slightly "stabbing". This ensures that the welder can clearly see the electrode tip and welding operation. If held too flat, the heat and inert gas is distributed too highly over the surface. This can result in faulty welding.

Typical welding faults: 

• Cracks  in weld result from excessively high welding currents or wrong wire electrodes, etc.

  Repair of such cracks requires grinding out the weld over the length of the crack and twice the depth of the crack before welding over. Then it is necessary to check again for cracks.

• Cracks  in the outer paneling can be repaired by first drilling a 2 mm diameter hole at each end of the crack in order to prevent further cracking. Then weld crack and holes shut.
• Pores  in the weld are one of the most frequent faults, whereby the tendency to form pores decreases with increasing solidification intervals. Pores result from the inclusion of gas bubbles when the weld cools down quickly. Other causes for pores are:
  • instable arc,
  • incorrect torch position,
  • quantity of inert gas too low,
  • effect of air drafts,
  • nozzle too small or clogged with metal spatter,
  • contamination in the area of the weld from grease, oil, paint or dirt.

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

Craters at end 

A crater is produced at the end of each weld, which must be filled. This can be achieved by not switching off the torch immediately at the end of the weld. The melting welding wire then fills up the crater.

Cold points 

The danger of cold points exists at the beginning and end of the weld which could have a negative effect on the strength of the connection as a result of notching. This should be taken into consideration by adding approx. 5 mm to the length of the weld at the beginning as well as end of the welds.