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#1
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Volcano plug welds ???....... (Mig type)
My longtime friend and swap meet buddy “Big Mike” is still banging out heavy collision work. He asked me why plugs welds (rosette welds) sometimes get a volcano effect. I told him contamination but have been second guessing myself on this all day on this. I’ve had the same effect and noticed just one pinhole in the center and no porosity on the sides so I’m kinda doubting my own initial comment.
So my first question is what are the theories on why mig welding plug welds occasionally gets this volcano effect ? And the more important second question is what is the cure ? Thank you in advance ~ John Buchtenkirch
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John Last edited by John Buchtenkirch; 05-29-2018 at 03:43 PM. |
#2
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I think contamination. Like paint or epoxie. Clean bare metal doesn't usually have this happen. What is strange is if it is still wet most of the time it doesn't happen . It just catches on fire.
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Mark |
#3
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John, I'm a heavy collision guy, and usually it's from contamination on the backside. Usually happens to me if I'm plugging a used panel. Especially if I don't take the time to get it completely clean of the various things they put on them now...foam, epoxy panel bond etc. Bigger problem for me is welding the various high strength steels on cars now with a conventional MIG welder. Nearly all cars '12 and up use it everywhere now and unless you are using a pulsed MIG it is very difficult to join the thin stuff to thicker stuff or multiple layered stuff. It just wants to burn as soon as the arc touches it. Forget making pretty nearly level plug welds like in days past. Heavier gauge stuff welds ok but I find it nearly impossible to put a conventional nice plug on the thin HSS.
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Chris (trying to be the best me I can be) |
#4
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Contamination from paint liquefying and outgassing as the weld fills the plug weld hole or rusty metal, could be on the back side where it isn't noticed.
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Robert Instagram @ mccartney_paint_and_custom McCartney Paint and Custom YouTube channel |
#5
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I think that you might be trapping shieding gas in.
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Mark Stefan |
#6
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I had that problem too. It was due to dirty metal. To solve this I took a drill bit the size of the weld hole and cut the cone off the end and then sharpened that end like an end mill. Using a hand drill use the drill bit to clean the base metal down to clean metal. It also helps to blow the hole clean with compressed air.
Mike |
#7
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I notice this happens a lot when you apply a rust convertor to the base, and on clean CRS it does it if you hold the torch head to close, so possible out gassing effect.
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John EK Holden V8 |
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