19 years ago
better answered here, and so I shall ask.
1) I was using my zircon (white) tungstens with AC on aluminum (supposedly
6061) today, and after a short amount of use they kept turning blue.
These are 3/32" tungstens on 1/8" aluminum, pure argon for a shielding
gas. My guess is this is resulting from the instructor's edict that
no student shall use more than 10 CFH of argon or have more than 5
seconds of postflow due to a slim budget for supplies (cutbacks in
California, dont'cha know). Is this the likely cause? I had less
of this when I used pure tungstens, which makes me wonder if they run
cooler or something of that sort.
2) For the aforementioned welding setup, what kind of amp range should I
be using? The instructor says "about 80 to 90" but my books and
reference card (one of those Miller sliding weld calculator things) put
it up closer to 125. Using the class machine, a Lincoln Precision TIG
275, leaving the dial set at 85 amps seemed to work fine. But on my
machine at home, a Miller Syncrowave 180SD, I couldn't even melt the
stuff with it set at 90.
3) My weld beads were looking awful today, and for some reason they kept
filling up with this skin of crusty black crud that looked like when
you weld stainless with improper gas shielding. Is this also something
that could be caused by a lack of shielding gas? When I did the same
welds at home with the same materials, the beads looked better but
had this sort of crystalline and sandy texture to them, even though they
were shiny and reflective. I was fairly careful about the cleanliness
of my setup... stainless steel brushed everything and then wiped
everything down with acetone, so it seems like it should have been
suitably free of contaminants. What sort of thing might cause these
4) The instructor gave us an equation to use for determining the amp
setting for a given tungsten. He said, "You multiply the diameter
of the tungsten by .125 to get the amps. So if we're using a 3/32
diameter tungsten, that would be 90 amps." Does anyone have any
idea what the hell he was talking about? What kind of new math gives
you a result of 90 when you multiply .09375 by .125? Ok, maybe that
one is a rhetorical question, but still.
Thanks in advance for any help... learning curves get mighty sharp when
books don't have all the answers and there's nobody in class to ask!