one for the professional arc welding guys

  1. duncans

    duncans Member

    Messages:
    683
    Location:
    leicester
    hello I've been on here a short while and what I've learned after advice and reading threads is if you are welding 6mm angle iron to use welding rods not to mig weld 6mm
    but this fabrication shop I've been buying angle iron from they are welding these big frames using the MIG welder I can see the mig is 3phase but a bit baffled
     
  2. Welderpaul

    Welderpaul Moderator Staff Member

    Messages:
    13,602
    Location:
    Yorkshire
    There's nothing wrong with mig welding 6mm. If there is, we're in serious trouble:whistle:
     
  3. duncans

    duncans Member

    Messages:
    683
    Location:
    leicester
    thank you for that welder paul at least I've learned something as im only a hobbyist
     
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  4. Hood

    Hood If it walks like a duck....

    Messages:
    12,596
    Location:
    Carnoustie, Scotland
    Most likely what has been said is that if you have a smallish mig then 6mm will be too much so better to stick weld it.
     
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  5. bourbon Member

    Messages:
    802
    Location:
    Lichfield UK
    It's about roots and building the weld up as I understand it. ( or am I talking ********?)
     
  6. Brad93

    Brad93 M J B Engineering

    Messages:
    10,397
    Location:
    Essex
    Hobby migs of 160A or less just haven’t got the power for 6mm thick steel.
    With a bigger mig of 300, 350, 400A you can weld steel of any thickness.

    if you’ve got a 160A stick welder you can weld 3.2mm rods at 130A all day long and you’re going to be getting adequate fusion.
     
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  7. Parm

    Parm Oh how I’ve missed my play pen this year

    Messages:
    13,104
    Location:
    Towcester
    Not all welders are equal
     
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  8. tom2207 Member

    Messages:
    2,520
    Location:
    uk northern ireland
    Basically , if you have enough power you can mig just about anything , a lot of us are limited to single phase and a house supply .
     
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  9. Brad93

    Brad93 M J B Engineering

    Messages:
    10,397
    Location:
    Essex
    There’s not much you can’t weld with 300-350A to be fair.
    1.0mm or 1.2mm wire provides a high current density, you’ll have no problem penetrating 1” thick material.

    Sensibly sized cover passes and you’ll have no problems.
     
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  10. grim_d

    grim_d Unlikeable idiot.

    Messages:
    3,103
    Location:
    Scotland - Ayrshire
    Let me just say I know absolutely nothing about welding compared to you, but surely with enough prep a 160A mig can do 6mm no problem?

    Assume you mean a plain butt join with no prep?

    I've welded 12mm rebar to 8mm box without issue with a 180A mig. The radius of the rebar and box made it like a v-prep though.
     
  11. Brad93

    Brad93 M J B Engineering

    Messages:
    10,397
    Location:
    Essex
    I’m talking about a t-fillet with no prep
     
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  12. metalmelt Member

    Messages:
    595
    Location:
    UK
    In the shop today they were working on a project and welding 24mm wear plates to 100 X 100 X 6 mm with MIG as this is the most prominent welding type for production work where speed is of the essence as stick, while perfectly acceptable, would be far to slow.

    As Paul says, "we're in serious trouble" as this section is going to site for erecting at the weekend.
     
  13. Munkul

    Munkul Jack of some trades, Master of none

    Messages:
    3,157
    Location:
    Cumbria
    With enough V-prep you'll get a good root pass in there, since the root material will be thin enough for the 160a to penetrate. But at 160a, you're not going to get it in a single pass - either the travel speed will be too slow, and you'll be too far back in the puddle for good sidewall fusion, or you'll have too small a weld throat. So you'd have to do multipasss.
    What I'd be leery about is on the subsequent passes, is now you have a good amount of metal in there for the 160 amps to be soaked up, and give you poor fusion.

    Let's be clear though, we're talking high quality welding here. It's borderline enough on 6mm that you'll generally have enough strength for non critical jobs if it's overbuilt to start with.

    There's loads of people who have bodged some MIG on 1/4" fillets and got away with it for years... including me... years ago we built a transport box for a tractor using a 160a mig and we didn't really have a clue about proper settings, just made sure it sounded and looked right...The 10mm thick main linkage brackets have never broke, and that thing got some serious hammer across fields for 15 years plus now! Yet I've seen plenty failures due to lack of fusion, including a couple of my own :ashamed:
     
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  14. Windy Miller Semi-Professional Potterer!

    Messages:
    2,940
    Location:
    North Kent, UK
    @Brad93

    So what could I realistically expect from my Lorch M-Pro 252? Currently using 1mm wire, but I have rollers for 1.2...
     
  15. Brad93

    Brad93 M J B Engineering

    Messages:
    10,397
    Location:
    Essex
    If you can get it to spray a 1mm wire you should see decent penetration to do a single pass on 10mm steel perhaps 12mm. Best way to check is a cut and etch.
     
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  16. Windy Miller Semi-Professional Potterer!

    Messages:
    2,940
    Location:
    North Kent, UK
    Would I need to change my shielding gas for this thickness of steel? I'm currently using Argoshield Light (or something like that!). Inside the machine there is a dial where I can select a particular setting from a printed table based on the wire type & thickness and the type of shielding gas. Irritatingly, there is no setting for the exact composition of gas that I currently use.
     
  17. Jay1st

    Jay1st AdeptusMechanicus wanna be.

    Messages:
    306
    Location:
    South West FRANCE
    Spray has nothing to do with the gas, if you're using an argon Co2 mix it's OK
    Spray is a very hot setting, the wire will vaporise instead of melting using short circuit welding.
     
    eLuSiVeMiTe likes this.
  18. Brad93

    Brad93 M J B Engineering

    Messages:
    10,397
    Location:
    Essex
    Spray has everything to do with the gas. It hugely affects the voltage at which the wire will begin to spray and makes a large impact on the visual and mechanical properties of the weld.

    And the wire doesn’t vaporise in spray transfer.
     
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  19. Jay1st

    Jay1st AdeptusMechanicus wanna be.

    Messages:
    306
    Location:
    South West FRANCE
    From what i did understand of spray transfer there is no contact with the work piece, no short circuit like regular MIG welding, and i was told as long as you have CO2 in the mix you can spray weld. It's a lot hotter than short circuit and gives more penetration
     
  20. Munkul

    Munkul Jack of some trades, Master of none

    Messages:
    3,157
    Location:
    Cumbria
    Mostly right :) only it's Argon, not CO2, which allows spray transfer. The higher the CO2 content, the more arc voltage is needed for a given arc length. So it's very, very easy to get into spray with 5% CO2, but will take a lot more volts with 20% CO2 at the same settings.
    The reason why 20% CO2 is regarded as a "Heavy" gas is because at those high voltages and currents, the CO2 keeps a shorter arc length, giving a stiffer weld pool and better penetration.

    It also doesn't vapourise. But it does form smaller droplets than the wire diameter. You can visually see the wire necking down to a point in spray transfer.
     
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