Today I was tigging a tooling fixture out of light steel. After an hour of fitting and welding I started to weld an inside corner on a piece of 12mm wide X 2mm thick strip. The arc turned into a flame and went crazy. A lot of it jumped at 45 degrees straight across to the strip instead of the corner. Some of this flame was coming back up the torch. I reground. Same result. I ground and cleaned a fresh tungsten. Same result. I ground off some carbonised paint 20mm away. Same result. I had used a power file to clean the join, maybe there was some alien metal deposited from the belt. Ground area with a clean disk. Same result. Pulled the torch apart and tightened, some of the joins had seemed loose, could be air in there.... same. There was a little draft, got rid of it ... same. The bottle was getting a bit low, but reset the flow OK... same. The cup was fairly blackened... replaced it.... same. Turned the strip over to try some fresh metal... same.
WTF ! but wait, this had happened to me once before........
Think you know?
There was one of those plasticy right angle welding setup magnets 100mm away. The only thing across the poles was the metal strip. The resulting field in the strip and the mainly open poles was really screwing the plasma. Somehow there must be a good use for this affect.
Rob Sydney Australia