Gas-shielded welding processes

Gas-shielded welding processes for aluminum

Welding under shielding gas is the welding method by which the peculiarities of aluminum welding can be handled best. The shielding gases used are usually inert gases such as argon (grade 4.8) or argon/helium mixtures (see Shielding gas for welding). In practice, there are numerous modified processes applied for certain welding tasks.

Gas-shielded arc welding is performed using a non-consumable electrode (TIG, see TIG process, Fig. 1) or a consumable electrode (MIG, abbreviation for metal inert gas, Fig. 2).

Manual TIG finishing welding with fillers of the same kind (see Welding filler) is used to eliminate the casting defects (cavities, mechanical damage, dimensional variations) that occur in casting practice.

The series welding of castings is mainly based on the MIG process due to the high welding speed. It uses direct current and an electrode of positive polarity. Today, MIG pulse welding is performed by robots and welding parameter programs in order to control the material transition from the wire to the casting with very differing wall thicknesses.

The plasma MIG process which exhibits an ideal arc formation and gas shielding is suitable for applications having high demands regarding tightness, surface quality and mechanical stresses, e.g. high-voltage enclosures (weld seam in Fig. 3).

Additional references:
Aluminum welding
Welding filler
Welding of die castings

Literature references:

DVS - Deutscher Verband für Schweißen und verwandte Verfahren e. V., DVS technical codes 0913-1 to -3, www.dvs-aft.de
DVS 0913-1 MIG welding of aluminium – Material-specific basics
DVS 0913-2 MIG welding of aluminium – Devices, processes, auxiliary materials
DVS 0913-2 MIG welding of aluminium – application-oriented notes

 

 

  • Fig. 1: Principle of the TIG welding process, source: Wikipedia Commons
  • Fig. 2:  Principle of the MIG welding process, source: Wikipedia Commons, author: Nathaniel C. Sheetz1) Feed direction2) Contact bush3) Welding wire4) Shielding gas5) Molten material6) Weld bead7) Base material
  • Fig. 3: Plasma MIG weld seam
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