Method to use welder to de-magnetize tools/parts?

[MR.57]

I was doing some 15-20 amp tig last week and was getting some nasty arc blow. Took me a couple minutes of re-arranging leads before I realized the vise-grip 11R's holding the part were the actual cause. The pliers had been in my welding bucket, stuck to a mag-base torpedo level for a while and had become magnetized.

I solved the problem by beating on the vise-grips with a 2 1/2 lb hammer a few times to knock the residual magnetism from them. Low tech, but it worked like a charm.

The experience got me thinking about demagnetizing though, I remember from working with a Magnaflux machine that there's a way to demagnetize parts using a coil and AC current. A coil was put around the part and the machine "pulsed" a gradually decreasing current AC field.

Could I do this in the field by using my welder by wrapping the work lead around the part and welding on a piece of scrap with AC at decreasing currents? Ex: Wrap lead around part a few times to make a coil, weld on a piece of scrap for a few seconds at 50 amps, 40,30,20,10 etc? Then proceed to weld on part with normal DC current. Would I have to decrease the current in steps or would one exposure to an AC coil at high amps get rid of the magnetism?

Seems like it would work in theory, I've just never actually tried it so I don't know the best way to do it. Obviously I can't use a sledge hammer on more precision parts/tools. AC welding isn't always an option.

Any thoughts?

[letzgoracin301]

I was doing some 15-20 amp tig last week and was getting some nasty arc blow. Took me a couple minutes of re-arranging leads before I realized the vise-grip 11R's holding the part were the actual cause. The pliers had been in my welding bucket, stuck to a mag-base torpedo level for a while and had become magnetized.

I solved the problem by beating on the vise-grips with a 2 1/2 lb hammer a few times to knock the residual magnetism from them. Low tech, but it worked like a charm.

The experience got me thinking about demagnetizing though, I remember from working with a Magnaflux machine that there's a way to demagnetize parts using a coil and AC current. A coil was put around the part and the machine "pulsed" a gradually decreasing current AC field.

Could I do this in the field by using my welder by wrapping the work lead around the part and welding on a piece of scrap with AC at decreasing currents? Ex: Wrap lead around part a few times to make a coil, weld on a piece of scrap for a few seconds at 50 amps, 40,30,20,10 etc? Then proceed to weld on part with normal DC current. Would I have to decrease the current in steps or would one exposure to an AC coil at high amps get rid of the magnetism?

Seems like it would work in theory, I've just never actually tried it so I don't know the best way to do it. Obviously I can't use a sledge hammer on more precision parts/tools. AC welding isn't always an option.

Any thoughts?

Being a NDE inspector we use an AC yoke energize it and slowly drag the legs across the part. then check it with a gauge gauge. also you can use a coil and slowly drag the part through not sure the best way to do it using a welding machine tho

[millrat]

Find yourself an "old" bulk magnetic tape demagnitizer. CL or ebay.

Same principal. Put to the object while slowly pulling it away.

You might even still be able to get one through Radio Shack.

millrat

[kevin]

i had the oppertunity to see this on a larger scale, my job was to weld connector ends to pipe for off shore drilling, 1 time we had a 30 inch pipe that would hold a heavy pipe wrench on its side from the magnitism, we would call xray and they would come down with some large coil wrapped around the pipe to remove the problem, it worked but i remember this really old welder laughing at this technique, he said that all that was needed was to wrap the ground around the pipe, put a piece of scrap into the pipe and weld the heck out of it, if my memory still works i think the stinger lead can be wrapped also, that just reminded me of what my son did years ago, i just bought a new tv, i just came home from work and asked him what he learned in school today, he said "nothing" but watch this, he took a speaker magnet and stuck it into the center of the tv screen, any one ever seen that done

[kbraby]

he took a speaker magnet and stuck it into the center of the tv screen, any one ever seen that done

Pretty soon, we will have a bunch of kids who have no idea what happens, because all they have seen are LCD flat panels.

Heck, I've done that to some pretty good TVs, but at least I knew how to have them degauss first...

[letzgoracin301]

i had the oppertunity to see this on a larger scale, my job was to weld connector ends to pipe for off shore drilling, 1 time we had a 30 inch pipe that would hold a heavy pipe wrench on its side from the magnitism, we would call xray and they would come down with some large coil wrapped around the pipe to remove the problem, it worked but i remember this really old welder laughing at this technique, he said that all that was needed was to wrap the ground around the pipe, put a piece of scrap into the pipe and weld the heck out of it, if my memory still works i think the stinger lead can be wrapped also, that just reminded me of what my son did years ago, i just bought a new tv, i just came home from work and asked him what he learned in school today, he said "nothing" but watch this, he took a speaker magnet and stuck it into the center of the tv screen, any one ever seen that done

never saw the magnet on a tv just youtubed that pretty cool..... there are tons of ways to demagnetize parts. although on critical parts you NEED to have a Gauss gauge. with out it you will never know if it is completely demagnetized plus with materials with high retentivity certain areas might demagnetize and others wont ex. crankshafts the counterweights tend to retain more residual magnetism

[OldSparks]

I'm presently in a magnetic playland....new construction on a 9% nickel storage tank, 180 ft. dia., 100 ft. high. The submerged arc horizontal machine can handle it pretty well but the dual shield set-up is hit and miss. The operator could be doing 10 ft. vertical seams and on one he'll have an inch of trouble every foot and on the next everything will be good except for a solid 2 ft. section. I come along and clean it up with inconel 3 stick. Gauss readings of up to 120 difference between sides of the seam. You could be putting in the nicest vert and then hit a spot where the parent metal spits your filler back at you, flux will fingernail for 1/4 inch. The company bought a Dynasty so we could try alternating current. Didn't work...the arc would just die or stick no matter how you exacting you were. Maybe there is some hidden code we should change??? Had to repair an overhead open root where arc refused to bridge and filler ran down the rod like wax on a candlestick.
We had strict rules about not dragging welding and rigging cables on plate but it developed anyhow. Then the company's own policy for ut scanning allowed the testers to use magnetic rails to guide their equipment. Don't know if that worsened the problem, but what it did was allow me to use magnets to do my repairs. When things are bad, a little positioning of a couple cheap magnets and everthing is sweet again. A lot of the time the magnets have to be reset after every rod. Our testers have told us about the industrial demagnetisers that are available but so far the company seems content to have us carry on as is. So goes it.
Pics show primered nickel tank being built inside completed mild steel shell.

[USMCPOP]

Stepping the current down won't work. You have to either smoothly ramp it down or gradually draw the object out of the magnetic field.

[ccawgc]

For small tools. A 25 foot weld cable with a 3 or 4 turn loop about 1 foot diameter. using an AC arc welder might work. Only turn it on just long enough to pull the tool through the loop. Make sure the weld lead can handle the current.
Using a DC welder will make a magnet.

[kevin]

i saw some thing on the science channel about the earths magnetic poles switching position, i dont remember how often that happens, but it does according to the scientest, just think of the poor guys welding when that occurs