Lincoln SAE 300 Magnetism

G6 at Snook, TX

Well-known Member
We had an interesting thing happen today. The SAE 300 I have was welding progressively worse throughout the day and it was acting like the pipe was severely magnetized. (We're rebuilding a stock pen with old oil field tubing.) Anyhow, it got to the point we switched to a Lincoln Ranger and there was no issue with magnetism at all.

The local welder mechanic we talked to suggested that the SAE had developed magnetism in the stinger (+) lead. The leads are wrapped around a standard homemade lead tree. Unwrapped the positive lead, stretched them out on the ground, and viola the SAE was back to normal.

For those who know, is that an occasional but common problem? Or if it recurs a symptom of a greater problem in the machine itself. The leads are 200' in total with them being 2/0 cable except a 25' whip end that is #1 cable. I'm in central Texas, it has been hot, and we've welded pretty hard the last three days. The machine is mounted on a trailer and properly grounded.
 
I worked for a pile driving outfit in
Anchorage for a few months one summer.
They drove used 6" well pipe through the
permafrost for foundations for a bunch of
duplex townhomes. We set I beam on top of
the pipe and welded it on. Then they
built the buildings on that.
The well pipe was highly magnetized. What
we did was wrap your stinger lead several
wraps around the pipe. Sometimes
clockwise, sometimes counter clockwise.
You had to experiment - number of wraps,
CW/CCW, etc. Sometimes you could wrap the
ground lead one way or the other around
the pipe and that would help. It was
kinda freaky how that magnetism would
blow your arc in odd ways. Never heard of
your leads getting magnetized though.
 
Welding is totally out of my realm of
knowledge but the tree you have your lead
wrapped on could it become magnetized and
create the issue? Just asking.
 
From another non-welder: My guess is the issue is not actually magnetism but rather the inductive effect the coil of wire has on the welding current. Therefore unwrapping the coil fixed the problem.
 
I'm not a welder but I worked at Lincoln in R&D for a number of years and did some robotic welding on linepipe. Sometimes moving the ground from one side of the joint to
the other had an effect. I think in your case it was just having the lead coiled. I worked in the robotics division for a while. The robotic cells came with a standard
25 foot controller-to-robot cables. In a small cell that was too much. Some customers didn't like the messy pile of cables so they hung them in nice neat coils which
screwed up the signals. I also notice that arc blow affects aluminum much more than steel. I designed a fixture for a customer to weld an aluminum drip pan. They built
the fixture from a large block of steel. Wasn't necessary for a light part but that's how it's often done. After 50 or 60 parts the welds went to h**l. Turned out the
block was magnetized. After degaussing the welds were good for a while.
 
Update: We unrolled the leads yesterday and had good success. Welded all day today and had nary a problem. Laid good beads and was smooth as a professional machine like an SAE should be.

What we experienced yesterday was the arc blow that s typical with magnetism. The fellow who was welding for me referred to it as some of the worst magnetism he'd experienced and it progressed from bad to worse as yesterday unwound.

We have come across plenty of pipe magnetized and we have done the wrap trick which works fairly well.

Thanks for the replies.
 
> What we experienced yesterday was the arc blow that s typical with magnetism.

Well, if you coil the leads, they will generate a magnetic field while you're welding. And that COULD magnetize any nearby steel, including whatever they're wrapped around. I can see if there's pipe laying in the vicinity of the coiled leads, some of the magnetic flux COULD pass through the pipe and affect your welding, even though the coiled leads are a long distance from where you're welding. Maybe.
 

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