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Welding Die-Cast Zinc Alloys?

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  • Welding Die-Cast Zinc Alloys?

    I've been lurking here for a while and just signed up to throw my 2 cents in recently. So now that I'm here (and to head off any ideas that I don't learn something new every day), I have a question for some of the more experienced welders.

    I'm sure that almost all of us have encountered broken die-castings. Not unusual since some have a ductile-brittle transition temperature not far below room temp. Has anyone got any tips/tricks for welding die-castings of high zinc content alloys like Zamac (ZAMAK)? I tried once some time ago... TIG welding/argon/various tungstens/polarities/etc and all I got was a crappy weld because it would pop and spit out metal before I could even develop a real puddle.

    I assume it was the zinc vaporizing before the other stuff (Al/Mg/Cu) was even halfway to their melting point. Being unable to weld inside of an atmosphere of 20 tons per square inch to keep the zinc from volatizing, I gave up. But I revisited this question last week when someone brought a GM tilt steering column to me that cracked when the 4 bolts deep inside backed out and let the wheel thump back and forth.

    I know this stuff used to get soldered with a special Cadmium alloy solder (EXTREMELY dangerous/toxic) but that's out of the question. Anyone recommend different gas, particular tungsten, AC squarewave, AC sinusoidal, particular balance, glovebox atmospere?

    80% of failures are from 20% of causes
    Never compromise your principles today in the name of furthering them in the future.
    "All I ever wanted was an honest week's pay for an honest day's work." -Sgt. Bilko
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    "Since we cannot know all that there is to be known about anything, we ought to know a little about everything." -Pascal

  • #2
    I've always been told it can't be done.

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    • #3
      http://www.crownalloys.com makes a torch repair rod for zinc aka potmetal. I have some and its Royal Kirkrod and it works pretty good. You see those guys at the flea markets/swap meets repairing junk and selling their brand of rod and they do a good job of fixing non critical parts. Royal Kirkrod 18" & 36" For Torch or Tig to Repair Zinc Based Metals..Bob
      Last edited by aametalmaster; 02-28-2008, 06:45 PM.
      Bob Wright

      Spool Gun conversion. How To Do It. Below.
      http://www.millerwelds.com/resources...php?albumid=48

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      • #4
        Die Cast Welding

        It was commonly done years ago. I myself have welded up a few of the older carb castings.I have a page scanned from one of my old welding books, but I cant get the file size small enough to post. If anyone wants it PM me with your address. In short you can use the aladdin filler rods with a OA torch, about a 3x carburizing flame and working the oxides out as you go. It can also be soldered usually with aluminum solders such as the ones sold by Brazing Technologies Group.

        -Aaron
        "Better Metalworking Through Research"

        Miller Dynasty 300DX
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        Miller Spectrum 375 extreme
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        Miller Spot Welder
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        Smith, Meco, Oxweld , Cronatron, Harris, Victor, National, Prest-o-weld, Prest-o-lite, Marquette, Century Aircraft, Craftsman, Goss, Uniweld, Purox, Linde, Eutectic, and Dillon welding torches from 1909 to Present. (58 total)

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        • #5
          I know I am resurrecting an old thread, but I have a casting I would like to repair. I've got some Dura-Fix rod, but the casting I wanted to repair started to melt before it would melt the rod. Is there anything else that might work. Maybe at a lower temperature.

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          • #6
            Solder it.

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            • #7
              Originally posted by Bob La Londe View Post
              I know I am resurrecting an old thread, but I have a casting I would like to repair. I've got some Dura-Fix rod, but the casting I wanted to repair started to melt before it would melt the rod. Is there anything else that might work. Maybe at a lower temperature.
              You'd think you'd give us a lot more to go on. Even if you don't know more, you can tell us what the part is, what the part does, and maybe even provide a picture so we could help you determine more about what the composition might be, or give you ideas for how to find out.

              You aren't even telling us what your procedure is, as in what kind of torch and gas (?) you are using. Knowing your level of overall experience also helps greatly for how to answer your question.

              This should have been its own thread with a specific subject line for your project. Being in this thread, are we assuming that we are, in fact, dealing with a zinc casting? If you read the thread, you'll get the idea, that there are no practical ways to weld it. Other options will depend on part design.
              Last edited by MAC702; 01-13-2019, 10:25 AM.

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              • #8
                I could be wrong but my guess is the 'pot metal' of yesteryear is long gone and most of those items are now a specific 'die cast' material. However die casts can still be made from quite a wide range of low melting point, mostly non-ferrous materials such as zinc, aluminum, tin, lead, magnesium and others. Each product made from a group best suited for that product and service duty. A guy probably needs to know a whole more about a particular item before even a wild guess could be made on how to. Just too many variable to make a blanket statement on 'how to".

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                • #9
                  Originally posted by Sandy View Post
                  I could be wrong but my guess is the 'pot metal' of yesteryear is long gone and most of those items are now a specific 'die cast' material. However die casts can still be made from quite a wide range of low melting point, mostly non-ferrous materials such as zinc, aluminum, tin, lead, magnesium and others. Each product made from a group best suited for that product and service duty. A guy probably needs to know a whole more about a particular item before even a wild guess could be made on how to. Just too many variable to make a blanket statement on 'how to".
                  Yup...Bob
                  Bob Wright

                  Spool Gun conversion. How To Do It. Below.
                  http://www.millerwelds.com/resources...php?albumid=48

                  Comment


                  • #10
                    Originally posted by MAC702 View Post

                    You'd think you'd give us a lot more to go on. Even if you don't know more, you can tell us what the part is, what the part does, and maybe even provide a picture so we could help you determine more about what the composition might be, or give you ideas for how to find out.

                    You aren't even telling us what your procedure is, as in what kind of torch and gas (?) you are using. Knowing your level of overall experience also helps greatly for how to answer your question.

                    This should have been its own thread with a specific subject line for your project. Being in this thread, are we assuming that we are, in fact, dealing with a zinc casting? If you read the thread, you'll get the idea, that there are no practical ways to weld it. Other options will depend on part design.
                    Its a pole saw.

                    I haint' never weldered no pot metal before...

                    I have used zinc aluminum alloy rod to bond aluminum before. Both Durafix and Muggy Weld rod. They both work ok.

                    Went at it with a propane torch. I also have MAP gas, and OA, and I have silvered soldered, silver brazed, and brazed, before and the first kind of welding I ever learned how to do was OA welding mild steel with a clothes hanger.

                    On this project I cleaned thoroughly with acetone, brushed to shiny metal with a stainless brush and then slowly tried to raise the temperature of the part until I could rub the rod on the part and melt the rod. Sadly the part started to melt before it got hot enough to melt the rod. I was using DuraFix rod. Its one of many used for this sort of thing with a melting temperature in the low 700F range. I chose propane as the coldest heat source I have that would still get the base part hot enough to melt the rod. Just being cautious.

                    Just to make sure my rod was still good I did some test welds on some pieces of aluminum flat bar I have laying around my shop, Welded just as good as I remember.

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                    • #11


                      **********UPDATE*********

                      I took it over to a buddy of mine who does a bit of TIG welding and he gave it a go. He tried low current with AC TIG and the max set at 75 amps and used the foot pedal to start lower. The first thing I noticed watching was the arc was red. We double checked on a piece of known aluminum and got the expected blue white arc. The other thing is the arc danced wildly. Back to the aluminum and a normal looking arc. The other thing was it just didn't seem to puddle at all. When he walked the pedal a little bit higher it just blew out metal.

                      We still don't know what it is, but we turned on all the fans and exited his shop after that to let the smoke clear... and there was smoke.

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