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I need help with the selection of a TIG welder. My primary uses for a TIG welder will be for butt welding 1) German silver (nickel silver) and 2) sheet metal for auto body work. For the foreseeable future I dont see a need to be able to weld aluminum but having the capability would a plus. I have virtually no experience with TIG but have done a lot with O/A so I am expecting a pretty good learning curve. For clarification German silver is a copper based alloy and has nickel and zinc in its composition so it canbe welded with a DC machine. For my application (radiator tanks) I need to do parent metal welds i.e. using strips of the parent metal as welding rods for a decorative application that will be polished. The material is approximately 0.040 inch thick. Silver solder is not an option due to the variation in color. This unit will be for a hobby shop and cost is a consideration but not the only consideration. I passed on a chance to buy a good used Econotig over the weekend based on reading the comments about the welders on this forum. The general consensus seems to be that it is not a good machine for this type of work that I want to do. All suggestions are appreciated. Alan
Reply:I have never welded german silver, but I have tig welded a fair amount of different copper alloys, bronzes and brasses. Zinc is nasty stuff to tig, if it is present in any significant percentage."German Silver" is kind of vague- there are a range of Nickel silvers, C 973 thru 978, that are commonly used, and the zinc percentage varies from as little as 2% to as high as 20%.This is going to make a difference in the weld quality.All of them are probably tig weldable.But when you heat up an alloy, as opposed to a pure element, the different metals will melt, and some will even vaporize, at different temps. So even using the parent metal as filler is no guarantee of color match, as the act of welding may change the zinc percentage, or the lead percentage, since they melt and vaporize at such low temperatures.In other words, might work, might not. I would want to make sure Tig will really do what you want before I dropped a couple of grand on a machine.Are other restoration guys tig welding german silver? If so, then color match is probably achievable. In terms of the machine itself, for tig welding .040 sheet metal, you need a pretty high quality machine, one that will go down to low amps accurately. You definitely need a foot pedal for control, and I would recommend a water cooled torch. Copper alloys eat up a surprising amount of amps- so your machine probably needs to be more powerful than you would think for such thin stuff. I would be looking at 150 amp and up machines.If it were me, I would find a full line dealer that carries both Miller and Lincoln, and take actual pieces of the metal with me, along with an experienced tig welder if you are not one, and insist on demos on the machines you are considering. This will give you a much better idea if the process will even work, and how many amps are really needed.
Reply:Thanks for the reply. You make a lot of good suggestions. A couple of things that I neglected to mention with regard to welding German silver is that I have welded it with an O/A torch with mixed success and a friend TIG'ed some pieces for me. He had pretty good success with the TIG but he is not an expert welder nor did he have a lot of practice with the German Silver when he welded my parts. Still they came out fine and the color match worked out fine when using filler material cut from the parent material. Based on what information I have I think TIG welding for this material is the way to go. The properties of the material I am working with are listed below. Alan C770 Nickel SilverMinimum Properties Ultimate Tensile Strength, psi 108,000Yield Strength, psi 89,900Elongation 2.5%Rockwell Hardness B96Chemistry Copper (Cu) 53.5 - 56.5%Iron (Fe) 0.25% maxManganese (Mn) 0.5% maxNickel (Ni) 16.5 - 19.5%Lead (Pb) 0.1% maxZinc (Zn) 27%
Reply:I would agree, tig is probalbly going to be the best.the lead content in this alloy is nice and low, which is good from a welding and fabrication standpoint. (not so good from a machining standpoint- they usually add lead to alloys to make it easier to machine)Thats a lot of zinc, though. Make sure you have good ventilation when welding it. You dont wanna breathe those zinc fumes, and they are the first out, since the melting point of zinc is so much lower than copper or nickel. |
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发表于 2021-9-1 00:12:12