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Gas Flow Rate for Mig

Wednesday, 18th March 2020
Graham (Tech Advisor)
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What’s the right Gas Flow Rate for a Mig is a question we get asked a lot, but like many things in welding, there’s no definitive answer.

The correct Gas Flow Rate for a Mig will depend on a number of factors:

  1. The diameter of the Gas Shroud
  2. The joint configuration
  3. Whether there is any uncontrollable factors that may disrupt the gas shield around the weld, draught/wind being the most obvious

Having said all that, I understand you need a start point, so I’ve produced a simple chart showing suggested Gas Flow Rate for a Mig.

This is based on a formula of the cross sectional area of the Gas Shroud Bore divided by 13.

For Example, let’s assume the Gas Shroud Bore is 10mm.

Cross Sectional Area (as I’m sure we all remember from school Maths), is

Pi x r² so:

Pi (3.142 is close enough) x 5 x 5 ÷ 13 = 6.042

We can round that to 6 litres per minute Gas Flow Rate for a Mig with 10mm bore Gas Shroud.

I would stress that this figure is a start point.  Try a test weld, if you see tiny pin holes in the surface of your weld, you need more gas, but in still conditions, this formula should provide enough shielding without wasting gas by using more than necessary.

I hope this helps

If you would like a higher resolution copy of the chart, use the “Contact Us” link on our website to drop me a note and I will email you a copy.

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

The Welders Warehouse

10 responses to “Gas Flow Rate for Mig”

  1. Chris Battle says:

    Hi Graham,

    That chart (table) is useful. It is hard to get relevant information from all the stuff on the Net, or from sales staff in retail outlets.

    Specifically, I am focused on one task: welding patches on an automobile body where I have cut out the rust. So far I’ve gathered Argon mix gas and .6mm wire, but I’m waiting on a 10mm bore nozzle, which may be better than the stock 12mm bore nozzle in some circumstances.

    Besides the parameters of wire feed speed and gas flow rate, my power source is a bank of 18650 Lithium ion cells, arranged as 5 serial and 12 parallel, which gives me about 20 Volts and heaps of amps, so I’m working on ways to control and adjust those parameters.

    Cheers,

    Chris Battle

    • Graham says:

      Hi Chris
      Glad you found the blog article useful. Your power source set up sounds interesting! 20 volts is pretty good for Mig, although a little high for the thin sheet steel of an automobile body.
      Good luck with everything.
      Cheers Graham

  2. Paul Smyth says:

    Excellent articles on welding well worth a visit to this site.

  3. John Sandell says:

    Great web site and very useful info.

    • Graham says:

      Thanks John
      Everyone here works hard to offer the best possible service & experience for customers, so it’s nice to know it’s appreciated.
      Cheers Graham

  4. Clive says:

    Very useful tip on calculating gas flow rates. Thank you

  5. Kris says:

    Hi any welding information would be greatly welcomed. Fairly new welder and eager for any info tips etc thank you kris

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