MIG Welding Thin Aluminium

  1. Ferrino New Member

    Messages:
    5
    Location:
    San Diego
    I have some aluminum car bodywork which I need to fill some holes on. The panels are flat sheets and ~1mm thick. The holes are ~8mm in diameter. I have good access to the rear of the holes. Plan is to fill holes and then grind flat for primer/paint, so I don't need an aesthetic weld - it will be sanded flush.

    I have a Hobart 140 MIG welder. Is there any way I could use this with argon gas and aluminium wire (and possibly a spool gun) to fill these holes? I was thinking I could punch small discs to fill the holes and then gently tack all around the discs to weld them to the panels (to reduce any warpage).

    Will this work or should I just pay a mobile TIG welder to come and do the job? Does aluminium tack weld like steel with a MIG? There is no structural component to these sheets I'm filling - I just want to fill the holes for paint. Thank you.
     
  2. 123hotchef Member

    Messages:
    8,071
    Location:
    Kent
    give it a go mate if not i have seen those sticks you melt with a blow torch they may work if the mig does not
     
  3. Lazurus

    Lazurus Member

    Messages:
    590
    Location:
    Norfolk uk
    I have used a spool gun on ali although not quite as thin as this and the results were pretty good, maybe a heat sink on the rear and just fill the holes?
     
    123hotchef likes this.
  4. 123hotchef Member

    Messages:
    8,071
    Location:
    Kent
    he wants to fill the holes with ali! i think lol,
     
  5. Lazurus

    Lazurus Member

    Messages:
    590
    Location:
    Norfolk uk
    Yes that is what I was refering to - fill with Ali weld with the heat sink to help prevent warping
     
    123hotchef likes this.
  6. Brad93

    Brad93 M J B Engineering

    Messages:
    5,914
    Location:
    Essex
    You’d need a copper “spoon” behind the hole.

    Expect some distortion
     
    henry Kadzielski and 123hotchef like this.
  7. Hood

    Hood Forum Supporter

    Messages:
    9,058
    Location:
    Carnoustie, Scotland
    You are not going to get a sound MIG weld on 1mm Alu with anything other than a pulse MIG. Having said that you are just wanting to fill the holes so it may be possible to deposit some metal in which would be good enough. I would try and clamp a bit of stainless in behind the holes and use that as a backing. I would just get a teflon liner and give it a go, no point in getting a spool gun for a few holes.
     
    henry Kadzielski and 123hotchef like this.
  8. slim_boy_fat

    slim_boy_fat Forum Supporter

  9. 123hotchef Member

    Messages:
    8,071
    Location:
    Kent
    slim_boy_fat likes this.
  10. stuvy

    stuvy Member

    Short answer no

    The cost to swap a mig over and the heat distortion your better off paying someone to do it for you with a tig
     
  11. Hood

    Hood Forum Supporter

    Messages:
    9,058
    Location:
    Carnoustie, Scotland
    To my mind Tig would give rise to more distortion especially as the MIG weld would have to be very cold to work on 1mm, then again I have only ever attempted to weld 1mm with a pulse Mig so...
     
    123hotchef likes this.
  12. johnik

    johnik Member

    Messages:
    415
    Location:
    sunny Somerset
    i used some "melt sticks" to mod an inlet manifold, it worked quite well considering the size of the casting so i would thing as others have said, worth a go with a piece of ally sheet on the inside:flame:
     
    123hotchef likes this.
  13. stuvy

    stuvy Member

    Tig is more precise as to where your heat input is
     
  14. Hood

    Hood Forum Supporter

    Messages:
    9,058
    Location:
    Carnoustie, Scotland
    But will have to put a lot more in.
     
    123hotchef likes this.
  15. stuvy

    stuvy Member

    True but having used a spool gun at work it’s a hell of a lot more going in to then grind back, huge amount of heat from grinding that back
     
  16. Brad93

    Brad93 M J B Engineering

    Messages:
    5,914
    Location:
    Essex
    Tig will give more distortion
     
  17. Hood

    Hood Forum Supporter

    Messages:
    9,058
    Location:
    Carnoustie, Scotland
    I wouldn't be getting a spool gun, certainly not for 1 or 2 holes and a 140A welder is not really capable of doing MIG welding correctly on Aluminium if intending to do thicker material in the future. Thus, as I said earlier, just a small roll of wire and teflon liner if he wants to give it a go.
     
    slim_boy_fat likes this.
  18. hotponyshoes Member

    Messages:
    1,249
    Location:
    Somerset. Uk
    I have access to both tig and pulse mig but for this job I would feather out the edges of the hole, glue a piece of alloy behind it and fill with body filler.
     
    anto44, slim_boy_fat and stuvy like this.
  19. Ferrino New Member

    Messages:
    5
    Location:
    San Diego
    Thanks all! I've tried the "aluminium brazing rod" that you use with a mapp torch on a 1mm test panel, but the heat introduced some pretty bad waves.

    That's an idea I've seen used before, but I'm concerned that the filled holes will be noticeable after paint (especially as one of the panels is right next to the exhaust manifold). If you were to go down this road, which type of filler would be least susceptible to shrinkage? Would you use a short-strand fiberglass filler? Thank you.
     
  20. hotponyshoes Member

    Messages:
    1,249
    Location:
    Somerset. Uk
    Evercoat rage ultra.
    Will bond directly to the alloy. Dont know what sort of temp it will withstand but I have seen paint bubble from overbaking and the filler has been ok so you won't want to be getting it that hot!

    If the panels are that close to a manifold I would wrap the exhaust or stick some heat reflector on the inside of the panels anyway but as above, I expect the paint will give up before the filler does.
     
    slim_boy_fat and stuvy like this.
Advertisements