thanks awill4wd, this is a bar and plate core, so the area you weld to is a bunch of stacked plates, I have welded half of it, I didnt contaminate the rod or tungsten any , but every time I dipped the rod I would get little black chars in the center of the puddle.
after welding the bottom endcaps on, I went back and filed the welds down smooth, the went over it with a Stainless steel Hand brush and then with a Stainless wire wheel.
then when I go back to weld, and once again every time I dipp the rod I get soot, but whats odd is I can just run over the filed down weld with the pulsed torch and it looks perfect.
Why would the contamination only show up when I dip the rod?
Btw I have tried rods dipped in acetone, wire brushed and sanded and dippd in acetone, with the same result.
In prepping the bar and plate tank i put two pieces of 1/4" flat bar on each side of the surface to be welded (to protect the charge face and ambient face fins). this leaves only the edge exposed. I used a SS brush with firm, long, slow, deliberate strokes until it was very very shiny, then wiped in acetone.
Are you backgassing your endtanks? I havent tried that yet and I was thinking maybe the heat on the surface was sucking air through the weld. But really I am clenching at straws right now. :(
Tom,
Back purge won't help in your case. However, if you are penetrating thru to a back side that is not as clean as the front than you will have problems.
Your "little chars" sound like one of two things. Bad gas or insufficient cathodic cleaning action on the reverse polarity side of the half cycle.
What are your balence control settings? Your synchrowave 350 has a balence control from 1-10 if your setting is 7 or above back it down one step at a time and see if there is any difference.
If your test piece is wrought and your intercooler is a casting you may very well have different balence control requirements to get a clean weld.
If your argon was bad your aluminum test piece would be bad also. I have encountered contaminated argon that was such that you mild steel and stainless would appear normal while aluminum would look very bad.
anyhow, let us know how it goes.
thanks for the info, I will adjust the balance and see what happens..
Also Is it possible that there can be bad "spots" in an argon tank? Because I have noticed a pattern that when i get halfway down On my argon I will see problems... but then It may just be me thinking so..
Thanks
Tom, bar & plate cores are even worse to weld than tube & fin because you don't know just how they have been put together and what process they have used to "bond" all the plates together.
Even on bar & plate I/coolers I build I still file the surface back to clean metal. I place a plate alongside where I want to file so I don't damage the core fins and get it right back to bare metal, it's easy to see as it's nice and shiny.
If it's a particularly dirty weld, which can occur, I will then place a cap weld over the top after cleaning the weld back with either a file or a tungsten carbide cutting wheel (very careful when using this).
If it's a "dirty" core I'll use 4043 or 4047 filler which seems to have nice wetting at the edges if it's all clean I'll use 5356 filler.
I also like using gas lenses, I seem to get better gas coverage with them and I use approx 7.5 litres to 9 litres gas flow measured at the torch not at the gauge. (We're metric here in Oz, I don't how that equates to CFM)
Regards Andrew.
I didnt know how rewelding aluminum over and over on the same weld affects the strength, but I am glad to hear that its ok to grind down smooth and weld over , because this Is what am forced to do (because Of improper cleaning I suppose.)
I have always heard the reweld 304 Stainless weakens the weld but I didnt know if rewelding 6061 aluminum weakens it.
I am new at this and am just worried this thing might not hold the intended pressure now.
Thanks
Tom, with the pressures you'll probably run at you'll never break it. The only problems I've ever witnessed, (from other intercooler manufacturers) is when they use too thin a plate for the endtanks and grind/sand the welds down to get a smooth finish. I have seen endtanks split when done this way.
For this reason I like to use 2.5mm to 3mm alum plate, I fabricate them then I weld the inside of the tanks then attach them to the core and weld the outside. I pulse weld mine as I've worked out a really nice procedure in which the welds look fantastic and I never sand them off as I like my intercoolers to have that "custom" look.
Regards Andrew.
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