After reading, what I believe ,all of the forum posts on this
matter, I still have questions. Firstly I have tried DC inverter,
with commercial grade argon. Silver(de-ox) seemed to act like
aluminum, on dc tig welding. Oxide skin formed, preventing a clean
weld. So would I see a huge improvement using an a/c unit? Also I am
curious,if anyone has experimented with mig welding using same
filler wire metal.Again I do not know if AC vs DC is a factor.
I haven’t tried TIG or Mig on silver alloys but AC verses
DC, HUGE difference. Ac will help “penetrate” any
oxide skins (aluminum) with TIG but I know that AC on aluminum is a
must on MIG too. I assume for the same reason(s). I am sure you would
see some sort of a GREAT DIFFERENCE in trying AC verses DC.
I find no need to use AC when TIG welding silver, in fact I would
find that it comes in the way, as silver conducts heat so well that
I’m already having to turn up the amperage to fairly high levels
(compared to steel or stainless). With AC, a portion of your energy
is lost therefore I’d have to crank it up even further, thus a need
for a larger tungsten. It is similar to aluminum in that the heat
moves quickly and therefore you risk a melt out…but the oxide layer
is nothing like aluminum, it melts at nearly the same temperature.
Aluminum’s oxide layer is a ceramic and will stay solid while the
underneath layer melts. With good control and the proper gas lens
you shouldn’t be getting any oxides on your weld area, only hot areas
outside of your argon coverage.
Your best bet is to dump a little heat into the metal, then quickly
push the amperage up until your pool forms and move quickly across
the weld area.
I’ve been meaning to play around with the pulse functionality of my
TIG to see if I can get a tighter weld. Practicing with copper has
also been a good help, nearly any you find on TIG
welding copper will be useful in welding silver.
Scott
in Oakland, CA where the rains have finally come.
Thanks scott for the input. Actually when i was trying to tig weld
fills of silver casting pits with dc it seemed like the oxide coating
stayed solid while the inner layer of silver was the one flowing. So
i took a piece of scrap alum and the results were identical. Now I
agree that argon flow and cup protection were a good part of the
problem. I just wish I had access to a really good a/c d/c tig welder
without purchasing to experiment. I wish there were rental or demo
units, but I have not been sucessful. Oh BTW I am using on De-Ox
sterling that my factory produces.
I swear there was some discussion of a small Miller TIG unit that somebody was using for precious metals welding on here a couple of
years back.
It was a $5000 unit then, IIRC.
I think it came up in context of a discussion of the PUK welders. Go
digging through the archives for PUK or TIG references, and you
should find it.
A guy called Kevin Lindsay did a paper about it at Santa Fe a few
years back, and there’s a Goldsmiths’ Guild research paper on it
available for download heRe:
Go to Utube and look under PUK welding machines made in Germany by
Lampert. These are micro tig welders that will show you demos of them
in action, I have own and it’s great for all metals and alloys. I
never used it on alum and don’t think it will work effectively.