Welding Aluminum...

I'm trying to understand the process behind welding aluminum.
I think I understand the physical basis for AC TIG on aluminum,
the ac tries to reduce/remove the oxide to give a clean weld. The welder manually adds filler rod and all is well;-)
My real question is how does aluminum wire feed welding work? Do you still use AC? If you don't use AC how do you keep the aluminum oxide off the weld?
What is typically used to weld Aluminum in a production environment?
How are large things like welded aluminum boats constructed?
Can some one reccomend a good background article on the basics of the different welding technologies?
Paul
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you MIG aluminum with a spool gun. the wire is not stiff enough to push all the way through a MIG lead (maybe 060 wire is, but large wire is not so common) and done with DC. the metal needs to be real clean to start with. the IG in "mig" helps shield the al, and a procedure for moving fast enough is learned with experience. if you dont move fast enough the al ahead of your path may get hot enough to start oxidizing....
AC gives some other adjustable chracteristics, such penetration or cleaning effects.
i'm just a hobby weldor, so others here may lend some more "welding tech talk" to what i have said.

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snipped-for-privacy@netburner.com wrote:

I am not an expert, don't even play one on TV. But you weld aluminum with DC when using wire feed. With TIG you don't want to use DC with electrode positive, because it gets the tungsten too hot. But it can be done. But with wire feed getting the wire too hot is not a problem.
MIG is usually used to weld aluminum boats. In a production environment, it might be TIG or MIG. Depends more on what is being welded.
Dan
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Here you will find general knowledge on TIG and MIG (GMAW) welding
http://www.millerwelds.com/education/bookspamphlets.html
other pages
http://www.google.com/search?hl=en&q=mig+aluminum&btnG=Google+Search
Richard

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Aluminum boats are almost exclusively done with MIG. TIG is too slow. Pulsed current is very popular for aluminum boats because it leave a cleaner weld ( no spatter) and vertical welding is easier. With proper equipment and skill even thin material is welded with wire feed... The thinnest I saw was a repair on a large hovercraft with 2mm damaged skin. It was repaired with MIG in pulse mode. A friend of mine had to qualify on this flat, vertical, and overhead. It was way beyond my skill level. Randy
I'm trying to understand the process behind welding aluminum.
I think I understand the physical basis for AC TIG on aluminum, the ac tries to reduce/remove the oxide to give a clean weld. The welder manually adds filler rod and all is well;-)
My real question is how does aluminum wire feed welding work? Do you still use AC? If you don't use AC how do you keep the aluminum oxide off the weld?
What is typically used to weld Aluminum in a production environment?
How are large things like welded aluminum boats constructed?
Can some one reccomend a good background article on the basics of the different welding technologies?
Paul
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R. Zimmerman wrote:

In production shops it is common to use a push-pull feeder for the wire. This way you can run BIG spools of wire and still have perfect wire feed of the soft AL wire.
These units are not cheap but will pay for themselves in time saved in one boat or less.
A spool gun is great for a hobby welder or for repair welding but one pound at a time is just wasting time when welding hull plating.
michael
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