Larry Jaques wrote:
On Wed, 25 Jun 2008 16:21:41 GMT, with neither quill nor qualm,
quickly quoth:
You can MIG aluminum?!? (I _just_ picked up on that.)
Yeah, you sure can. But like he said, you have to use a different gas.
You have to use pure Argon instead of the standard 75% Argon 25% Co2 which
is normal for mild steel.
You have to use aluminum filler wire of course, and that creates a problem
because it's so soft it's hard to push feed without jamming. The normal
way to mig aluminum is to use a spool gun which pulls the wire from the gun
instead of pushing it from the welder. (or use a push-pull system for a
larger set-up). This makes it rather expensive because of the extra cost
of the spool gun (many hundreds of dollars). The Millermatic 250 series
supports two guns connected to the machine at the same time so you can have
it configured to do either steel or aluminum without changing guns or wire
and the runner cart that goes with it will hold two tanks so you can weld
either by just picking up the right gun.
With the small Lincoln machines you can buy an aluminum "kit" which gives
you a different gun cable liner and I think different feed rollers made to
push aluminum without marking it. Even tho ugh it's a push configuration
I'm told it works. However, you have to take it apart, switch cable liners
and rollers and wire, and switch the gas tanks to convert from steel to
aluminum so it's a real pain to do. And you do have to be very careful
keeping the cable fairly straight. If you try to cheat and not switch
liners, I think for one, it's more likely to jam, and two, you are likely
to get steel dust contamination on your aluminum which will cause problems
with your welds. But, you can mig aluminum with it and the add on kit
isn't that expensive so it's a nice option to have.
The miller units don't have that add on kit. They tell you to buy a spool
gun (for $500 dollars?).
Aluminum conducts heat away from the weld faster than steel so it takes
more heat to weld aluminum than steel for the same size material. As such,
the small mig machines (which can't weld very thick steel to begin with),
have any more trouble trying to weld thicker aluminum.
I much prefer TIG for aluminum and my personal plan is to get a machine
like the Miller Dynasty 200 for steel and aluminum (TIG and Stick). Unlike
MIG, you can use one gas (Argon) for both steel and aluminum with TIG so
it's easy to use one machine for both. Of course, decent TIG machines are
in a different price bracket than the small wirefeed units. I'd like to
get a small wirefeed as well but I'd just use it for steel.
--
Curt Welch
http://CurtWelch.Com/
http://NewsReader.Com/