Welding metalwork pieces such as those made from
aluminum is relatively easy as it melts at a much lower temperature and
does not crack after solidifying. Aluminum welding is done according to
the type of aluminum used such as commercial grade aluminum having 99
percent purity, non-heat treatable alloys containing small amounts of
manganese (Mn) or magnesium (Mg), and heat treatable alloys containing
copper, silicon, zinc, or magnesium.
Work pieces made from these
types of aluminum are easier to weld whereas aluminum work pieces
containing copper or lead additives are difficult to weld and often
lead to cracking while welding.
Aluminum welding methods include
MIG and TIG welding, apart from conventional techniques such as gas,
plasma, resistance welding, and welding with covered electrodes. The
TIG technique is used when there is a need for good surface finishes
and when welding from one side is not accessible, such as when welding
pipes, and when repairing castings. The MIG technique is better suited
for welding thicker aluminum work pieces at a faster rate and for
achieving long, continuous welds. This technique has a lower heat
input, which results in less distortion in the welding zone.
The
latest aluminum welding technique involves the use of pulse arc welding
combined with MIG that give much better results as compared to
conventional methods. This technique gives better control of the molten
pool in the case of thin material, makes the arc more stable, reduces
spatters, and mitigates the risk of welding imperfections.
Welders
need to take a few precautions while welding aluminum work pieces as
the higher melting point of oxide that forms on its surface, when mixed
into the molten pool, can cause welding defects. The surface of work
pieces that are to be welded need to be scraped or brushed clean using
stainless steel wire brush immediately before welding.