magnetic work piece holder

[Didd1]

Could anybody tell me does a magnetic field effect the arc when mig welding?
been fairly new to mig welding and just got hold of my first full bottle of CO2 I thought I'd run a few test welds, After two runs I had it set up perfect until I tried welding a T-piece that was held in place by a magnet, when I started to weld I found it tended to spit and the resultwas as though I'd welded it without any gas. I don't think it was anything to do with the way I was welding as I took the magnet away an it seemed to weld fine.

 

[rtbcomp]

I found that it did with my AC buzz-box. I got a heavy vibration (50Hz) when welding near to a magnet and the arc seemed less concentrated.

 

[Fergus]

I tried using a rare earth magnet (from a hard drive) to hold a patch in place and found the same thing when welding near it.

Up to that point is was doing a cracking job...

 

[Didd1]

The magnet in a hard drive are really strong but how does it cope as an earth I kind of like that Idea.

 

[jinjahbiscuit]

The magnet in a hard drive are really strong but how does it cope as an earth I kind of like that Idea.

It's nothing to do with the "earth" - I take it you mean your earth return. It's just a name for some permanent magnets made from alloys of metals like cobalt and neodymium, yes they're stronger than normal ferrite based magnets. They're not even that rare really.

 

[Fergus]

The magnet in a hard drive are really strong but how does it cope as an earth I kind of like that Idea.

I wouldn't bother with them for earthing purposes, it would be a ball of swarf and filings in no time.

 

[lionleg]

They do affect the arc , I forget the technical term for it. If you must use them then remove them after tacking up otherwise you will struggle, especially if you are inexperienced.

 

[Didd1]

Good point Fergus I never thought of that

 

[Jim Davey]

It's called 'arc blow' more of an issue with arc welding than it is with mig but it can be a real pain if the metal you're as become magnetised. There are things you can do such as wrapping the earth leads around the job etc to attempt to counteract the magnetism but it often doesn't work. Using a smaller rod and keeping the arc length short is often a good way to overcome it.

 

[sapperb]

YUP, YUP the magnets do effect your weld result. I use then only when I Tack, that is it.