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Resistance Spot welding question

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  • Resistance Spot welding question

    Hi Everyone, I am brand new here and look forward to talking and learning from you all. I am an novice/intermediate welder that is self taught from books/vids/welding practice.

    Up to now, I have been satisfied with my skill, but now I would like to take it to a different level. I am looking into welding school (I know that is the absolute best way besides experience), but I hope to get even more of an edge talking to you experienced welders.

    I recently bought a Miller 220V res. spot welder (can't remember the full no. but I think it had "LM" part of it). It works very nicely and I am getting much better at using it. My only problem is that when I finish the spot weld, the contacts are sticking to the steel. It is regular mild steel sheets, between 20 ga. and 16ga. .

    I am getting good welds with good fusion, but many times, the contacts stick and when I pull them apart, it leaves small traces of the copper electrodes. I tried some anti spatter, thinking that it will stop the sticking, but for the same timing as a previous weld, it burnt through the steel much faster and splattered alot.

    Any help with how to stop the sticking?

    Thanks very much,

  • #2
    Touch them up with a file. Make sure they are clean copper looking...Bob
    Bob Wright

    Spool Gun conversion. How To Do It. Below.


    • #3
      Tell us more about your equipment. Are you using water cooled tongs? Does your spot welder have a timer? How are the tongs actuated? Is it a manual pinch with your hands on a lever, or foot operated, or pnuematic?

      More than likely you are getting the weld too hot or you are arcing at the tip face. Make sure that your material is very clean on all sides.


      • #4
        Thanks very much for the responses. The tongs are perfectly clean and lined up. It is not water cooled, and no timer. It is manual pinch with manual lever. I have practiced alot with it and have achieved pretty good timing and resultant welds. I got a good divit front and back without squeezing the metal out. I did a few distuctive tests with good results.

        The only problem I have is the tong tips sticking to the base metal, and when I pull them off, it leaves small amounts of trace copper in the weld area.

        I noticed in the instructions, it says not to use the welder as a clamp, and to adjust the tension so that it is not overly tight. The steel is brand new and freshly cleaned up on all 4 sides. I use vice grips to get very good fitup, and I adjusted to tongs so that it contacts, but does not act as a strong clamp. Maybe this is the problem. Do you think it could be too loose? Would that cause this condition?

        Thanks again.



        • #5
          Still looking for any help.

          It has been almost 2 years...and I am still looking for any help. Haven't done much practive with this spotwelder, but I did enlargen the tips to about .200"

          what do you all think?



          • #6
            I have no experience with what you are working with, but sounds like you have been thoroughly testing different settings and with all the things you tested I guess you might have stumped some people to not get an answer.

            Got any pictures? They always say a picture is worth a thousand words. Maybe of your setup and pictures of the end weld result with the trace copper left.

            Is it depositing copper every time? Only at the end of the weld? I do know someone here at my work that works with spot welders for photomultiplier tubes. Different application, but maybe he would know something.


            • #7
              Hello Greg

              Heat generation in resistance welding is of resistance in between the weld surfaces. When the electrode-metal resistance is more than faying surface, the heat generation will be more on the electrode surface than the faying surface. Please check the force applied.
              Also if the weld cycle starts before proper squeeze of the plates, the electrode can stick to the plate.


              • #8
                fandrose, welcome. But I'm guessing Greg is not listening. His last post was over 7 years ago. Anyway, you're thinking he was not using enough clamping force?