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  1. #1
    Join Date
    Mar 2008
    Location
    South Coast, Australia
    Age
    62
    Posts
    225

    Default MIGS, TIGS & Magnets

    Today I was trying to TIG up small mild steel bracket that I had supported from behind with one of those magnetic squares and I was trying to get a bead on the other side of the bracket. For the life of me I could not get the arc to sit anywhere near the joint. After a few tries I was thinking what metal have I used that is making the arc behave so erratically. I thought bugger this and got the MIG onto it and although it too struggled at first to lay down a bead where I wanted it, got a very big bead down and although it was ugly as sin, the job was done. Reflecting some time later, I figured it must have been the magnetic field from the square that was playing havoc?
    He Who Dies With the Most Tools Wins

  2. #2
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

    Default

    Yes, it happens. PITA and I’ve pretty much stopped using magnets for that reason.

    Steve

  3. #3
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

    Default

    Likewise. I'll use them to hold 'the other corner', but not the one I'm trying to weld if I can at all help it.

    Michael

  4. #4
    Join Date
    Dec 2018
    Location
    NSW
    Posts
    586

    Default

    It's called 'Arc Blow'. Common around magnetic fields.
    There are some tricks, you can buy dedicated degaussing machines to de-magnetise materials, but in your instance it's introduced magnetism, so remove it from the equation.

    I've also heard you can wrap the earth clamp cable around the workpiece to introduce an opposing eddy current... but never tried it.

  5. #5
    Join Date
    Sep 2006
    Location
    Australind , WA
    Age
    58
    Posts
    1,277

    Default

    Well, I didn't know that would be a problem!
    I was planning using some magnets to hold steel projects.
    Guess I'll have to use something else, or keep it as far away as possible.
    Thanks for the 'heads up'

  6. #6
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Quote Originally Posted by Sterob View Post
    Well, I didn't know that would be a problem!
    I was planning using some magnets to hold steel projects.
    Guess I'll have to use something else, or keep it as far away as possible.
    Thanks for the 'heads up'
    Hi Steve, Guys,

    A magnetic field is some times used in circuit breakers and is designed to blow the arc away, extinguishing it, when the contacts open.

    All currents flowing in a circuit or through an arc produce a magnetic field that can be influenced by another magnetic field.
    Best Regards:
    Baron J.

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