The laser beam can be guided to a robot head by light-conducting filaments, spot diameters of a few tenths of a millimeter allow accurate joint preparation, reproducible fixing of the components and precise programming of the tracking path. Component tolerances can be compensated within certain limits by the cold-wire feed, while "hot-wire feeding" (in which the filler is brought to temperature by resistance heating) gives even better process reliability and welding speed. Tests on aluminium light-weight structures led to interesting results: a hot-shaped section of AlMgSi0.7 with 3 mm flange thickness could be welded to a 1.6 mm thick AlMg3 sheet at speeds of more than 2 m/min (laser power 3 kW). Good welding results were also achieved on panels for rail vehicle construction. This suggests opportunities for combining laser welding with a MIG arc, as described below. Whether the term "hybrid welding" is particularly appropriate for this, is an open question; the term "laser-MIG welding" seems to describe what is involved well enough.
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