Setting Up for Aluminium Welding
Aluminium welding is possible with
just about any MIG welder, but aluminium wire is much weaker, more sticky,
and expands more than steel wire so you'll need to take a few steps
required to set up the welder to prevent wire feed problems.
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Crumpled Aluminium Wire!
Aluminium wire is much softer than steel wire. I took a photo of my
first aluminium welding experience. The wire folded up in the wire feed
as soon as I struck an arc!
This was very frustrating and you'll find a few posts in the forum
about this and the rest of my learning experience. The main problems
were down to the wire liner and tip. |
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Oversized Tip
There are a couple of reasons the wire crumpled up in the rollers.
The first is that aluminium expands much more than steel when it gets
hot and seizes inside the brass tip.
The way around this is to use an oversized tip. I used a tip designed
for 1.0mm steel wire for running 0.8mm aluminium wire. |
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Plastic Wire Liner
Aluminium wire is "stickier" than steel wire and will tend
to pick up on a steel wire liner. Replacing the steel liner with a plastic
one seems to get around this problem. Teflon liners are recommended.
I've extended the liner as close as possible to the wire rollers to
reduce the distance the aluminium wire needs to travel unsupported.
Halving the distance between the rollers and the liner will quarter
the chances of the wire crumpling up. |
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Pure Argon Gas
The final step is to arrange a supply of pure argon shielding gas.
The photograph shows a small 60l gas bottle connected to the gas hose
via an imperial brake pipe fitting (naughty).
These bottles last for about 1 metre of welding, and I got through
three of them in my early stages of practicing before deciding a full
sized bottle would be much more economical. |
Wire Diameter
The wire feed speed for aluminium welding is about twice that of steel welding
with the equivalent diameter wire. That means you can use a thicker wire for
aluminium. A thicker wire will be less prone to birds nesting. Use 1.0mm diameter
aluminium wire instead of 0.8mm wire.
Wire Roller Tension
The roller tension can be vastly reduced as the rollers will grip the aluminium
wire much better than steel wire. Excessive tension could cut a sharp edge into
the wire which might wear through the wire liner and increase friction. Rollers
with "U" shaped grooves rather than the standard "V" shaped
grooves are available and would presumably reduce this problem.
The set up above, combined with a straight as possible welding cord should
result in a trouble free wire feed for aluminium welding.