welding a magnet?

  1. welder Member

    what is the score with trying to weld a magnet does any1 no scientific reason why u cant?
  2. Archie Member

    Posts: 2,305
    UK
    Well apart from the fact that I'd have thought you'd trash the magnet...

    Apart from lots of heat the arc also creates it's own magnetic field. Can't believe either would be good for a magnet. Then there's the material magnets are made from. Often they're rare earth metals, not good old fashioned iron/steel.
  3. Drains

    Drains Yeah, nah.

    Posts: 7,672
    Soggy Sefton, NZ
    Some magnets are sensitive to heat. Some perhaps arn't of weldable material. Otherwise, I don't see why you couldn't weld to a steel magnet. On AC, of course.

    Ach, bloody Archie :mad:

    :laughing:
  4. TIG Paul

    TIG Paul Moderator Staff Member

    Posts: 3,733
    Northampton. UK
    One of my customers uses very powerful ceramic magnets mounted over conveyors carrying meat products, its virtually impossible to weld within about a metre of them,
  5. malcolm

    malcolm Administrator Staff Member

    Posts: 8,220
    Bedford UK
    Magnets might tend to attract the arc on DC, so Si's AC suggestion might well be sensible. That's assuming the magnet is made of something weldable. There was talk of wrapping the earth lead around the work a few times to reduce the effect of arc straying, but the references for that are all to do with magnetised steel rather than your actual magnet. Which would be much more magnetised.
  6. snowcat

    snowcat back in black Staff Member

    this is reasonably common in petrochemical where the drill heads become magnetized and turn pipelines magnetic, It was also a phenomenon that could happen on 5 rail work, as the high voltage DC and the running load would cause magnetism to occur, the general consensus is to demagnetize if possible, forget DC that simply will not work, A/C will be far more stable, but depending on the strength of the field it can still cause problems.....
  7. rtbcomp

    rtbcomp Moderator Staff Member

    I used an AC stick welder near a magnet once, the arc was very noisy and spattery.
  8. snowcat

    snowcat back in black Staff Member

    Ohhhh and doesn't AC passed through a magnet demagnetize it anyway?? so if you want it to stay magnetic this may not be the way.....
  9. TechnicAl

    TechnicAl Member

    Posts: 2,297
    Rotherham
    Forgetting about the magnetism problem. The alloy used to give the best magnetic properties is very hard and very brittle. You could smash it with a hammer if you really try.

    Obviously something this hard wont be weldable, it would be like trying to weld glass.

    The localised expansion caused by the heat of welding would be enough to crack it
  10. scarecrow

    scarecrow Outstanding in his field

    Posts: 1,628
    Ireland
    Isn't there Something about using a magnetic drill while welding on a piece of iron thought it had something to do with DC I must look for the manual later on
  11. simon718

    simon718 needs to stay off ebay

    Posts: 2,015
    Norn' Iron
    might be something of interest in this thread?
  12. Psymon

    Psymon Member

    Posts: 228
    Essex - UK
    Oh don't you love science?
    Heating a magnet destroys the magnetism.
    Magnetism is only made up of the magnetic field being aligned along the metal in question. Heat it and this jumbles up the magnetic field de-magnetising the material.
  13. wannabewelder Member

    Posts: 52
    Norfolk U.K.
    High temperature kills magnetism.
    Once you exceed the Curie point materials loose magnetism. There's lots of detail on http://www.answers.com/topic/magnet
    Seems strange that magnets should be used as welding clamps when heat can destroy them.
    The most powerful magnets are "rare earths", usually neodymium based, and the curie points can be very low http://en.wikipedia.org/wiki/Neodymium_magnet plus as been stated before, many magnets are ceramic rather than metals - probably as easy to weld to as glass - unless you have some high faluting pulsed laser or something!

    wannabewelder
  14. stormin Member

    If it's a magnet that's broken in pieces:-

    i) It should stick back together with it's own magnetism.
    ii) Gluing it together with a strong epoxy adhesive would be better than welding.
    Similar to the above if you want to bond the magnet to some other metal part. Glue is how magnets are generally fixed in motors.

    Welding a magnet if it's steel or iron will, as others have said, at least partly destroy the magnetism with heat and AC current both affecting it. You could of course remagnetize by placing in a magnetic field such as the inside of a DC coil.
  15. welder Member

    so lads you are saying that you can weld It on AC?????????
  16. Archie Member

    Posts: 2,305
    UK
    I think the general consensus would be that you shouldn't weld it at all. :(
  17. chunkolini

    chunkolini celebrity artiste

    Posts: 6,379
    herefordshre
    Aaah Glasshoppers
    Does Mr Welder want to weld a magnet or do he just wonder if can weld magnet?

    I have Mig welded onto a big magnet to make a torch holder that sticks to a steel workbench, a horrible spattery process but it did work. A useful thing indeed.

    I have also monkeyed about trying to weld onto smaller magnets to get my head round what happens, the weld goes all to pot, spits etc and if it is a small magnet the magnet dies. Why? I was the child who put ants under a magnifying glass on a sunny day.

    Chunko'.
  18. Psymon

    Psymon Member

    Posts: 228
    Essex - UK
    1) A magnet will stick back together if it is broken. However the act of breaking the magnet will de-magnetise it a small percentage. The shock will jumble the magnetic field. Secondly when a magnet breaks it becomes really difficult to stick back together as there are stray magnetic fields pulling it one way and the other. ( depends on the size and thickness of the Magnet)
    2) Agree the best way is to glue any magnet onto a surface with some epoxy or chemical metal.

    The wife is a speaker engineer. She used to bring any spare magnets home for me to construct wind generators with. The lab used to have this box for magnetising ceramic magnets. You could dial in power and set it off. When you pulled the ceramic out it would stick to everything,great fun :laughing:
    Sometimes I would get neyo magnets they can be dangerous! Once they stick its very hard to get them off anything. If you want to get your hands on some neyo magnets then you currently have either one or two of them between a foot and 3 feet from where you are sitting now! They are built into all hard disk drives. Crack open an old one and dig it out. (look like little silver kidney shapes)

    Thinking that the best way to weld anything like this would be to construct a holder and then slide the magnet in from the side - I mean something C shaped and that way the magnet will grip everything without the risk of the heat killing the magnet.
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