Current Type for welding Aluminum
Current Type for welding Aluminum
(OP)
I have been researching welding units both MIG and TIG. Something has struck me as odd everywhere I read that you must have AC to weld aluminum when discussing generalities but then getting into specs of weld units and I see DC mig machines that are quite good at Aluminum. What is it about MIG that lets DC work for it but to TIG you need AC?





RE: Current Type for welding Aluminum
i beleive that welding alum must be with dc reverse polarity ......because alum forms oxides too fast and that causes internal cracks.......and because alum is a very good conductor of heat and not very high melting point ...because of all this u must weld it with dc reverse polarity....and i beleive that tig and mig makes no big dfferences.regards
RE: Current Type for welding Aluminum
I understand it is possible to weld thin aluminium with pure DC reverse polarity but have never seen it done.
RE: Current Type for welding Aluminum
RE: Current Type for welding Aluminum
RE: Current Type for welding Aluminum
http://www.esab.com/index.asp?item=14
RE: Current Type for welding Aluminum
In order to perform a good welding job on aluminium, besides an experienced and certified welder, it is needed to have an alternating current welding machine with a HIGH FREQUENCY UNIT built-in.
That high frequency unit basically helps to start the electric arc without any contact between the non consumable Tungsten electrode and the base material (working piece), keeping the electrode from contamination.
In addition, this high frequency alternating current allows the electric arc to disperse and pierce the aluminium oxide that forms on the working piece surface.
As an option for welding aluminium, a direct current welding machine, reverse polarity can be used.
Ricardo
RE: Current Type for welding Aluminum
I have been involved with studies that showed MC actually got better penetration. The balance was ~70%DC+. Theory being that the workpiece heated up as it is far more difficult to emit an electron from Al then from W. Therefore the base metal was much hotter, resulting in deeper welds.
Slightly off topic, but Ricardo's post mentioned the cleaning issue.