tig on aluminum..what the heck am I doing wrong?

Just tried to fix a part off my dad's 37' motor home. It's a diesel pusher
and the rear has a louvered hatch that is an aluminum frame with aluminum
fins going across it. Each fin is about 30" long and they're just tacked on
either end of the U shaped frame. Several of these have come loose and I
cleaned it all up, set my HTP Invertig to 140amps max, used a Lanth
electrode (1/16) cleaning/penetration in the middle, 150Mhz for freq and a
point on the electrode. I struck the arc and instead of a nice,
controllable arc I got this dancing wide looking firey thing. Tried
stepping up the amps and feeding a little 4047 rod in and the parent
material just kinda bubbled up and got all sooty. Parent material was
around 1/16 thick flat stock.
I got mad so I grabbed a piece of 1/8 flat stock that I had practiced on and
tried to run a bead down that...the electrode just kinda melted back up into
the cup and left a little soot on the piece. I haven't used this machine in
a few months so maybe I just lost what little touch I had??
I must have broken several rules here...anyone??
Thanks
J
Reply to
James Arnold
Loading thread data ...
Have you checked your shielding gas flow rate?
__________________ Note: To reply, replace the word 'spam' embedded in return address with 'mail'. N37.3 W122.0
Reply to
Barry S.
Yes..left that out...running around 15 on the flowmeter.
thanks
Reply to
James Arnold
ya..I can hear it and the gauge shows it has argon. It'll blow smoke away on post-flow if I aim the cup at some smoke.
>
> > Yes..left that out...running around 15 on the flowmeter. > > > > thanks > > > >
> > > > > > > > > >Just tried to fix a part off my dad's 37' motor home. It's a diesel > > pusher > > > >and the rear has a louvered hatch that is an aluminum frame with > aluminum > > > >fins going across it. Each fin is about 30" long and they're just > tacked > > on > > > >either end of the U shaped frame. Several of these have come loose and > I > > > >cleaned it all up, set my HTP Invertig to 140amps max, used a Lanth > > > >electrode (1/16) cleaning/penetration in the middle, 150Mhz for freq > and > > a > > > >point on the electrode. I struck the arc and instead of a nice, > > > >controllable arc I got this dancing wide looking firey thing. Tried > > > >stepping up the amps and feeding a little 4047 rod in and the parent > > > >material just kinda bubbled up and got all sooty. Parent material was > > > >around 1/16 thick flat stock. > > > > > > Have you checked your shielding gas flow rate? > > > > > > __________________ > > > Note: To reply, replace the word 'spam' embedded in return address with > > 'mail'. > > > N37.3 W122.0 > > > > > > I'm sure no expert, but I had the exact same symptoms when I forgot to turn > on the gas one time on aluminum. You sure it's flowing? > > Garrett Fulton > > > > >
Reply to
James Arnold
I'm sure no expert, but I had the exact same symptoms when I forgot to turn on the gas one time on aluminum. You sure it's flowing?
Garrett Fulton
Reply to
gfulton
I am no expert by any means as a matter of fact taking classes right now on TIG. you did not say what thickness is the piece you are welding and what type of aluminum. how ever 140 amp seems a bit high if it is 12 gauge or 1/8" at scool we use 100 amp on 1/8 alu. 20 CFM argon, A/C can't recall the electrode size....I think it is 1/16 or 3/32
but the electrode tip should have a ball instead of a point. the dancing arc reminds me of the pilot highfreq. arc. before the real arc jumps.
I would increase gas flow , and make sure you got argon in the bottle. also have good gound wire brush the piece to be welded.
tell us how it turns out..
Reply to
acrobat-ants
Might be a bad ground connection. Lazy arc seems to be that to me. Check the connection at the TIG and that on the Motor home - you might be going through bolts and not a good conductive path.
Martin
Reply to
Martin H. Eastburn
I am certainly no expert, but i have read that on inverter type TIGs, leaving the electrode tip flat (not pointed and not balled) works better than balling the tip. Either way, I have not read where you would point the tip for AC. My .02 Chuck
James Arnold wrote:
Reply to
Chuck Willis
The fins are about 1/16 or a little thicker. The electrode started as a point, but got to a ball quickly.. I'll double check the argon bottle..
Reply to
James Arnold
I should have said that I removed the hatch panel and was welding it on my table in the shop. I did ground to the chromed latch on the frame. Probably should have ground off some paint and grounded closer to the actual work area. Dad's on his way to Colorado with the coach now, so I won't get a chance to try it again for about a month...I will be playing with some other pieces of stock in the shop today..
Reply to
James Arnold
Thanks...got that from Ernie on this list. I'm pretty sure he told me that for aluminum AC you need a balled electrode...but..I could be wrong..
Reply to
James Arnold
It is difficult to say for sure. You can check gas (I see you already checked that, but maybe you have a wrong bottle). You may also have a contaminated tungsten, try a new one. Also: if, like me, you did not know that you must break the tip of the tungsten before regrinding it, you may have contaminated your grinding weel with aluminum. Then nothing works as it should untill you clean the weel and regrind the electrodes.
Reply to
jerry_tig2003
I think the name CHROME was it! Higher resistance than steel. Martin
Reply to
Martin H. Eastburn
Hi Jamie. I read all the other replies.
My first guess is a very thick oxide layer on the aluminum. Any part exposed on a trailer would get some serious weathering, plus it was likely anodized to begin with. You can't TIG weld through anodizing. It just makes a mess. You have to grind it off where you will weld.
You also can't TIG 1/8" aluminum with a 1/16" tungsten. It can't take the amps. Switch to a 3/32" tungsten. Grind it to a point and then let the ball form. Forming the ball on DCEP always makes a prettier ball than AC.
Another possibility is that the window frame is made from an aircraft alloy like 2024, which is unweldable. It could be soldered, but not welded.
Reply to
Ernie Leimkuhler
I should add that from the following passage, you seem to have tried welding on another piece, made of Al that should work:
This was of course one of the first things to try: if you can't weld something which you know welds well, you know you have a problem with either: -the machine -the gas or -the torch.
I suppose that the ground connection on this flat stock was right and that the piece was clean. If you have checked all the obvious like type of gas, correct adjustment of the welder (AC!), the only thinks I can think about are a contaminated electrode (as already said) or a contamination in the gas circuit (air leaking in or dirt in the torch).
Reply to
jerry_tig2003
Hi James,
Why do folks insist upon using pure Argon when AC welding Aluminum? Use helium, and start enjoying welding aluminum.
Ensure your ground is near the area being welded, and brush the aluminum at the weld, and where the ground is applied.
Regards,
Guy
James Arnold wrote:
Reply to
Guy Morin
Well pure helium can be a pain to use. The arc is much harder to start and the arc is much hotter so it is tricky to not blow holes through thin materiels.
An Argon / Helium mix however gets you the best of both gasses. More heat, cleaner arc, and easy arc starting.
Reply to
Ernie Leimkuhler
I'm doubting the gas contamination as this is a nearly new HTP inverter (probably less than 10 hours on it) and it's stored carefully in my garage shop. I'm thinking either bad ground (I let the piece sit on my table and grounded the table) or heavy contamination on the piece. I'm going to clean up the test piece, get a new electrode, purge my gas line and ground to the work this time. That's gotta be it. This worked great the last time I did it,!!!!
Thanks
Reply to
Jamie Arnold (W)
It appears to be welded..although very sloppily...looks like boogers of aluminum holding the stuff together...maybe migged...dunno. Dad is near Colorado now with the motorhome (37' diesel pusher bus thingy) so I can't play again until he gets back in a month. I'm guessing the heavy corrosion or contamination theory. While I cleaned it up "pretty good" I wanted to chemically clean it as well with some acetone...might have had some diesel crap on it...
Thanks, Ernie...hows the hand coming along??
Reply to
Jamie Arnold (W)
Hi Ernie,
We do agree that judicious use of helium is a must. Raising awareness on the subject seems to be a fundamental issue. Users seem to be reluctant to move to helium mixes because of price and dealing with having to get another tank, or the plumbing, and so forth. Yet, the ease of welding aluminum with helium, far outweighs the inconvenience.
At one end of the spectrum, the use of pure argon requires so much preheating as to cause the same problem with thin stock.
Personally, I find that the heat of helium is easier to control, even in it's pure form, than the problem of pure argon pre-heat. The preferred method is to use copper backing strips to manage thin stock behavior. The other part is to be quick with the filler.
Various mixes of helium and argon do allow the best of both gasses to contribute to aluminum welding. Argon contributes arc stability, while helium contributes high heat. I too have the combined setup with a tank of helium and one of argon that are wye'd together, and that allows various mixes to be dialed-in, and it works well.
Regards,
Guy
Reply to
Guy Morin

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.