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  1. #1
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    Default MIG torch diffusers - when to replace

    Is there a rule of thumb on when to replace the gas diffuser in MIG torch?

    I replaced mine last night - for the first time ever. I've had the welder for a few years but probably only put about 50kg of wire through it.
    I'd been having some weird arc stability issues, ground was good, tip replaced a couple of weeks back and not showing any signs of wear etc.

    After replacing the diffuser everything was fine, but I'm not sure if a diffuser could cause that sort of behaviour, or if the improvement may have just been a byproduct of pulling the bits out of the torch to replace it.

    Old and new for reference:




    Steve

  2. #2
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    Hi,
    Do you like to get the mileage out of your consumable components?

    Given that it is really not an overly expensive replacement part, m/y opinion is go for it.

    Bearing in mind that the gas also has an influence on arc ionisation and gas leakage might have an influence on that again,you have nothing to lose.
    regards

    Grahame

  3. #3
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    The one I replaced is definitely past its use by date
    I'd seen the discoloration etc when removing the nozzle to for cleaning, but honestly hadn't noticed that it had become so eroded until I actually removed it.

    I'm more than happy to replace consumables, but by the same token don't want to be throwing them away unnecessarily when they are working perfectly.
    Question is how do you know?
    Is it a case of any visible erosion is cause for replacement? Or should they be changed even earlier than that for some reason?
    Would it be reasonable to change at the same time you put a new roll of wire on perhaps...??

    Steve

  4. #4
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    Looking at the diffuser it is more a deposit of some sort.

    My guess it is from the metallic vapours in the atmosphere around the molten arc pool settling on the diffuser.

    Throw in a metallic oxide mix and grinding between the nozzle and diffuser -around the bottom half.

    I am interested to know if there has been an obvious difference in performance between old and new.

    Grahame

  5. #5
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    There was a definite improvement after the replacement - the erratic arc issue was completely gone.
    As I said though, I'm not sure if it was the diffuser replacement itself that fixed it, or just that the replacement process has sorted out some other issue with maybe the tip electrical connection etc.

    Its more than just a deposit on the old one though - that was where I got caught out originally thinking the same thing.
    Its actually quite eroded, if you look at the 8.30 o'clock position on the old one you can see the top edge is almost a knife edge with no flat left, and quite a thin web compared to the new one. Seems to be almost eroded in facets.

    Steve

  6. #6
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    Hi Steve, you certainly got good mileage out that diffuser, 1 diffuser to 4 rolls, our blokes do the opposite, 4 diffusers to 1 roll, well just about. The biggest problem we have here, is that the blokes just tap hit the nozzle against what they're welding to clean out the crap caught in there. THAT certainly doesn't do them any good.
    I change mine when the gas starts playing up, causing porosity in the welds.
    Kryn
    To grow old is mandatory, growing up is optional.

  7. #7
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    If you want to check if it was the diffuser causing your problem, put the old one back in and give it a test. That should answer your question.

    Cheers Andrew

  8. #8
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    That diffuser surely wasn't doing your gas flow any favours.
    What you were seeing would have likely been atmosphere drawn in thru the erratic, turbulent airflow from that diffuser- you can have all the holes clear, but when you start creating turbulence, the gas can tumble and create vortex/cyclone formations which suck in air, and cause problems.

    Understanding it's a whole different process, the same thing happens with TIG collet bodies - which have gas holes similar to mig diffusers, as opposed to gas lenses which have a filter screen to promote laminar flow from the cup. More turbulence = more chance of whipping atmosphere back up into the gas flow and onto your weld.


  9. #9
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    Since the torch had a birthday present with the new diffuser - I thought it might be happier with a new nozzle too




  10. #10
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    The old diffuser only has a single clear hole I can see. The unit appears to be designed with six holes . I am with Commander Keen on this.

    Gas flow and turbulence are a very big deal in mig welding.

    Nozzles and diffusers to a lesser extent require on going maintenance. I worked on pipework that required radiographic examination on each weld.

    Stopping the weld and cleaning the nozzle on a regular basis meant I never had any crud drop off the inside of the nozzle or diffuser into my molten weld pool. Thusly no welds were failed.

    Using nozzle dip and a pair of mig pliers is the way to .The tapered edge of the pliers is designed as a corer for cleaning out the crud in the nozzle.

    Also as the top of the nozzle became uneven ,I would dress it back to a concentric edge with a flat file.

    Could I ask what material was being welded. I not seen plain steel do that to a diffuser in a decade of coded welding.

    Grahame

  11. #11
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    Grahame, it was probably the galv coating that did it, whilst welding his trailer, I see this a LOT where I work, usually on my welder as I'm not as rough as the others, who break theirs.
    On thing I did forget to mention Steve, is to clean your mig liner occasionally with compressed air.
    Basically disconnect the torch assembly from the welder, usually a nut with hand grips, and insert the blowgun nozzle into the liner where the MIG wire runs into, preferably with DRY air, using a moisture trap.
    Every so often I remove the actual liner, and blow it out as I bend it to remove any larger particles trapped with in.
    As you welder sits, being unused, the MIG wire collects dust that is transferred into the liner, eventually making it hard for the wire to smoothly travel to the nozzle/tip. Even if covered, moisture creates minute rust spots and the rust particles can be transferred/ scraped off into the liner.
    Kryn
    To grow old is mandatory, growing up is optional.

  12. #12
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    Default MIG torch diffusers - when to replace

    Grahame - as Kryn said I've done a fair bit of duragal welding recently when I built the big trailer recently, so that will definitely have contributed.
    As much as you try to remove the coating with a flap disc there's always some residue around.
    All the holes in the old diffuser were still clear apart from one partially blocked.




    I don't have any nozzle dip, so typically just clean the nozzle with the MIG pliers and then give it a quick quirt with anti-spatter. Often I do that once the nozzle is back on the gun (which is probably not ideal) so may be ending up with some getting up around the diffuser, and subsequently burning on. May explain some of the black.
    Although I've only put about 4 rolls of wire through it, I've had the machine and torch for about 10 years, and welded whatever plain steel I've had to glue together in that time. Hasn't been used for anything exotic like stainless or hard facing etc.

    Kryn - good point on the residue in the liner rusting when sitting around. I was aware of the dust generation, but thought it was more related to just total wire volume. Hadn't considered the effects of the machine being unused for extended periods of time.

    Thanks everyone for the good info.

    Steve

  13. #13
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    I'm sorry but that looks more like a fossil from the iron age.

    Jack

  14. #14
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    If you are feeling fancy, Binzel do a ceramic nozzle spray which is laden with ceramic. There is a little cap that goes on top of the can, and you just dose the nozzle when needed. It's like teflon for your front-end. It's the bee's knees. It'll pay for itself in increased consumable lifespan- I got a can for about $30, and the nozzle which goes onto the next can was about 15. So not horrendous, especially if you use a bigger 350-500A torch with expensive parts.
    Some fellas I know in a concrete plant put me onto it, and swear by it for all the Reo welding they do for a range of the bits they make. Lots of tacking up, out of position, short runs, and all the other dirty contaminants they get on the job that makes life a pain, and would normally chew thru torch consumables.
    Ideal for gal- the sparkly spattery zinc dingleberries don't even get a chance to burn in.


  15. #15
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    Thanks Commander - looks like a pretty slick system.

    I found this short video on how its used: https://www.youtube.com/watch?v=50z0p4KdHu4

    Steve

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