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Welding Aluminium with Mig

Thursday, 19th March 2020
Graham (Tech Advisor)
The Welders Warehouse Online Shop

Firstly, Mig Welding Aluminium with a general purpose Mig Welder is not ideal, a DIY type machine is even less suitable.

The best type of machine to weld Aluminium with is an AC/DC Tig Welder

Having said that, with the right set up, most Mig Welders can be used for welding aluminium (more or less), provided they’re set up correctly.

The challenges of Mig Welding Aluminium

Mig Welding steel is not difficult, this is because when it comes to setting the machine up:

> Roller Tension

> Torch Liner Quality

> Power Setting

> Wire Feed Speed

there is a reasonable margin of error.

For example, if your wire feed speed is a little High, or Low, you’ll get away with it.  If you’re trying to weld Aluminium you WON’T get away with it.  Wire feed speed that’s too low will cause the wire to burn back on to the Tip, too high and it will hit the job, potentially causing a “Birds Nest” of wire inside the machine!  All very frustrating.

For Mig Welding Aluminium, you will need:

> Pure Argon Gas, NOT Co2 or an Argon/Co2 mix

> Plastic or Teflon Liner in your Torch (more on this later)

> An oversize Tip for the end of the Torch (more on this later)

> A Reel of Aluminium Wire suitable for the grade of Aluminium you intend welding

> LOTS of patience getting the Power and Wire Feed Speed right

Mig Torch Liner for Mig Welding Aluminium

A Regular steel liner (looks like bicycle brake cable), will scrape the surface of the Aluminium Welding Wire, causing the wire to bind/jam in the liner.  A Plastic or Teflon Liner MUST be used to avoid this.  If your Mig Torch already has a plastic liner, but you’ve been using it to weld steel, I would recommend fitting a new liner for Mig Welding Aluminium.

Oversized Mig Tip

Because Aluminium has binding properties, it may jam in a regular tip, especially when the tip gets hot.  Some types of tip can be purchased in an “Aluminium” version, these are slightly oversized to compensate.  If your machine’s tip type is not available in an Aluminium version, I would suggest using 1.0mm tip for 0.8mm wire.

Aluminium Mig Welding Wire

Several grades of Aluminium Mig Welding Wire are available and the grade selected needs to be compatible with the Aluminium to be welded.

If your welding a straightforward commercial grade of Aluminium, my suggestion would be to use a 5356 grade Aluminium Mig Wire  You can use a 4043 grade, but this is a softer wire and therefore more prone to feed problems.

Setting up for Mig Welding Aluminium

OK, you’ve got Argon Gas, you’ve fitted a Plastic/Teflon Liner and oversized tip and you’ve fitted your spool of 5356 Welding Wire.

Next you’ll need to place close attention to the tension on your feed rollers.  Ideally, you’ll be using ‘U’ shaped rollers, but if all that’s available for your machine is ‘V’ shape, these will have to suffice.  Set the Roller Tension AS LOW AS POSSIBLE.  Do this by starting at a point where the rollers slip and don’t feed the wire.  Then slowly increase until the wire does feed OK.  More info on Roller tension can be found in our Knowledge Zone

Power Setting

This will be determined by the job.  If you’re an experienced welder of steel, start by setting the Power about 50% higher than you would for the same thickness of steel.

Wire Feed Speed

This will be determined by the job.  If you’re an experienced welder of steel, start by setting the Wire Feed Speed about 100% higher than you would for the same thickness of steel.

Ambient temperature

If you’re doing a job in cold weather, try warming the job up a little.  What you’re looking for is the job to not be cold to the touch, so if it is, put a fan heater on it for a few minutes.  A job that’s warm to the touch will weld easier.  This shouldn’t be necessary in Summer.

Getting Started – Patience Patience Patience

Make sure metal you intend welding is clean, running a sanding disc over the area to be welded can also help if the aluminium is old as this will reduce the effects of surface oxide.

Getting the balance of Power and Wire Feed Speed when trying to Mig Weld Aluminium is a frustrating exercise of trial and error.

Start by angling the torch at 45⁰ as this will minimise the risk of birds nesting wire inside the machine if the wire feed speed is too high.

Once you’ve got the Power and Wire Feed Speed set correctly the process is not dissimilar to welding steel.  Hold the torch at around 70⁰, and move slowly along.

I hope you found this useful, if things work out well for you, please feel free to post some pictures of your achievements on our Facebook Page

Please let me know what you thought of this article by leaving a comment.  Don’t worry, your email address won’t be added to a database or shared and you won’t receive any unsolicited email.

Cheers

Graham

Online Store

13 comments

  1. Avelardo Vidad says:

    i encounter so much problem with ER4943 1.2mm specially on cable liner that, it always block on contact tip so i can’t weld continuously. maybe the cable is too soft that can’t hold enough the straightness of the liner or maybe the liner itself doesn’t fit the filler wire. may i ask for a suggestion?

    1. Graham says:

      Hi Avelardo
      Sorry for the slow reply.
      Are you using a Telflon Torch Liner? If not, this may be part of the problem as Steel Liners will cause jamming.
      Also check the size of your Tip, there are oversized tips for Aluminium, if you can’t get one of these, fit a tip that is one size larger. For example, if you have 1.0mm wire, fit a 1.2mm Tip.
      Also check the Roller Tension in your wire drive is not too tight. If it is, the rollers can squash the wire so it is no longer round, this will definitively cause jamming! Make the roller tension as light as possible without the rollers slipping.
      Hope that helps
      Cheers Graham

  2. zidane says:

    very clear and good article easy to understand. Thank you

    1. Graham says:

      Thank You for your comment Zidane. Glad you found the article useful.
      Regards Graham

  3. Foz says:

    Aluminium has a much lower melting point than steel so why the higher juice.???

    1. Graham says:

      Hi Foz
      Mostly the high heat conductivity of Aluminium. As you put heat in, it’s being conducted away to heat up the rest of the material (this is why Aluminium is used for Heatsinks in various industries). So to melt a very small part of the Aluminium to form a weld pool, you need to overcome the loss of heat to the rest of the job. You can get away with less power if you pre heat the Aluminium.
      Hope that helps
      Cheers
      Graham

  4. Foz says:

    50% higher on the juice are you sure you don’t mean lower

    1. Graham says:

      Hi Foz
      See my answer to your next question.
      Cheers
      Graham

  5. Makemoneywelding says:

    Great Post!! Thanks for sharing helpful information with us. Keep Sharing…

  6. Mark says:

    Hi
    I want to weld 65x16x1.2mm vertical aluminium slats
    to a 5mm aluminium base with a Mig welder.

    Do you have any advice?

    1. Graham says:

      Hi Mark
      1.2mm thick Ali to a 5mm thick base is a bit of a challenge with Mig. Assuming you have experience of Mig Welding Aluminium, the main thing is to err 60-70% of the arc onto the 5mm base, otherwise you’re going to blow the 1.2mm away before you fuse to the 5mm. I would also warm the base plate up a bit first, the hotter that is the less arc power it will need to fuse to it, thus reducing the power differential between the two different thicknesses of Aluminium.
      Good Luck, post a reply letting me know how you got on!
      Cheers
      Graham

  7. Vinayak Khandekar says:

    WE INTEND TO WELD TOGETHER TWO 100MM X 6MM ELECTRICAL GRADE ALUMINUM BUSARS /FLATS.PLEASE SUGGEST SUITABLE PROCESS AND WELDING WIRE FOR THE MIG 250 ESAB MAKE WELDING MACHINE.

    1. Graham says:

      Hi Vinayak
      I would suggest a 1.2mm wire of a grade suitable for the grade of Aluminium the Busbars are made from, plus Pure Argon Gas. You should also use “U” Grooved Rollers in your Mig. You would need to speak to ESAB for anything more specific as we are not familier with the details of their Mig Welders.
      Regards Graham

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