New TIG welder - weld contamination

  1. olmasters Member

    Messages:
    20
    United Kingdom
    Hi all,

    I've not posted here for years, but am a long time lurker.

    I'm a design engineer by trade, but have been TIG welding for the last 6/7 years for the odd job required every month or so for my employer. Parts have all been stainless, much of it textured around the 1.2-1.5mm thickness mark.

    Below is a typical example - 6mm flange welded to 1.5mm 7GM stainless hopper. Not perfect, but gives some indication to my standard. This and all my experience in TIG so far has been performed on a 10yr~ old CEA Rainbow 160A~ DC TIG unit.

    [​IMG]

    Having left this employer, I'm keen to keep up with TIG so this week purchased a Jasic PRO TIG 200P AC/DC - Steve at Weldequip was very helpful, pricing was really competitive and he got this sent out asap!

    I set this up yesterday for DC welding with the following:
    • Supplied WP26 torch, electrode negative (This is large, so will likely move to a smaller CK torch in due course, I did order it with the foot pedal, but keen to dial in with the torch first)
    • New pack of tungstens (I've always used 2.4mm, although a little large - kept with that for this setup, as that is my experience so far) ground correctly on a clean wheel, tungstens cleaned with acetone afterwards
    • CO2/Argon mix bottle from my MIG - purchased from SGS
    • New 1.6mm 316 stainless filler rods, cleaned with acetone
    • Several strips of 2mm thick 304 stainless sheet - grinder cut, deburred with a flap disc and cleaned with acetone
    • As a ball park, setup the welder based on the forum guides

    With up to 14l/min gas and a No8 cup, everything cleaned with acetone (far cleaner than I'd admit to usually being!) I seem to be getting contamination pretty much instantly. With the tungsten 1mm~ away from the material (stickout is from welding an inside corner), with no dipping, within around 20mm the tungsten looks like the image below:

    [​IMG]


    Below is the outcome, TIG setup to around 65/70A, much colder than this adding filler is problematic. Travel speed and filler add rate is comparable to previous work on the CEA. Outcome has no bead definition and an odd bubbled texture to it. This is similar working on mild steel with mild filler also. Thinking this could be due to the 2.4mm tungsten, I did dig out and grind the only 1.5mm I have - sadly made no difference.

    [​IMG]


    Below is the outcome from pulsing (bear with me, im new to this!) at 5hz 50% on time, max 95A, min 40A, no filler. As before, poor bead definition, same odd texture to weld.
    [​IMG]


    To be honest I'm pretty stumped, having done a fair few hours on TIG prior, I thought it would be fairly straightforward to configure the JASIC and get cracking.

    I've played about using very clean materials, the max volume of gas my flow meter will allow and have welded at a wide range of amplitudes, from far to cold, to excessively hot with different travel speeds. The only way I can seem to avoid the finish shown above is to run the torch close to 130A for 2mm thick material and move around 40mm/sec, which is a little quick for me to add filler!

    if anyone has any bright ideas, it would be much appreciated.

    Cheers
    Ollie
     
  2. no idea Member

    Messages:
    130
    CO2/Argon mix bottle from my MIG - purchased from SGS - If that's the gas you're using then you need to change that to pure argon.
     
  3. eSCHEn

    eSCHEn Bit Wrangler

    Messages:
    5,580
    Location:
    SW Scotland
    To my amateur eye they look like something's problematic with the gas. Reading back you mention running at 14L, I'll assume that's LPM and if so then you're pushing a lot of gas for the cup size. This can actually cause issues with coverage so I would try dropping your flow in half to 7LPM and trying again. Like I say Ollie I'm no expert but they do look familiar to when my gas isn't set up correctly.

    Edit - @no idea has it spot on. You need pure Argon for TIG.
     
    stuvy likes this.
  4. olmasters Member

    Messages:
    20
    United Kingdom
    Thanks very much guys, glad its something simple!

    I was so sure I'd previously been using some argon/CO2 mix from Air Products with the CEA, but clearly I'm a wally! :ashamed:

    Off to the gas supplier I go!

    Many thanks all
    Ollie
     
    eSCHEn, stuvy and Brad93 like this.
  5. Brad93

    Brad93 M J B Engineering

    Messages:
    5,957
    Location:
    Essex
    Aside from being the wrong gas, the gas flow is too high.

    You want about 7-8lpm through your #8 ceramic
     
    stuvy likes this.
  6. olmasters Member

    Messages:
    20
    United Kingdom
    Cheers Brad - appreciate the advice, I should have mentioned I began around 8l/min, just moved up incase coverage was at fault.

    Off I trundle to buy pure argon!
     
    Brad93 likes this.
  7. Migmad New Member

    Messages:
    4
    Location:
    Staffs
    As above mate pure argon for tig
    Mix for mig
     
    doubleboost likes this.
  8. doubleboost

    doubleboost Member

    Messages:
    2,623
    Location:
    North Easr England
    Easy fix
    Decent welds with mixed gas
     
    Ali likes this.
  9. Ali

    Ali Member

    Messages:
    312
    Location:
    Cheshire
    your wallet will appreciate the lower consumption now you’re paying for it yourself, flipping stuff costs a fortune and you can’t even see it. I would’ve had to give up trying long ago at 14lpm.
     
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