While I never did a lot of aluminum, I found that if I sooted the parts I was working on, with a high carborizing flame from an Oxy-Acyteline torch, no Oxygen, acyteline only, then heated the part to the point where the soot disappeared, and then welded as quick as possible, I eliminated the problems you are descibing. Aluminum obtains oxides from the atmosphere very quickly. 20 CFH should be enough gas to provide adequate gas coverage.

Mike

Hello Dave, you've probably been told much of what I mention before, however, you might want to start at ground zero and work your way through the basics from A to Z to ensure that you're not missing anything on the way that your system is set-up. Start with all hose connections, fittings, and the hoses themselves, check for holes, loose connections, etc. Consider your welding area, is it drafty or windy at all?, is the stickout on your tungsten excessive and do you have all of the parts of the torch in their proper places?, do the collet and collet body match the specific diameter of the tungsten that you are using and is the collet facing the correct direction?(I have run into a situation where the collet was in backwards and it caused turbulence in the gas stream to the extent that porosity showed up in the finished weld). If you are using a water cooled torch and have a sheath over all of the supply hoses is there any possibility that something could have fallen on the gas supply hose and punctured or cut this line or possibly burned a hole in it? Is there any possibility that it could be kinked inside of the sheath where you could not readily see it? On a lot of tig torches there are those fancy little white nylon/plastic spacers that seperate the cup from the main body of the torch and also seperate the backcap from the main body of the torch, are these in place and in good shape? When you take the backcap off of the torch are the sealing o-rings on the backcap in good shape and in their proper place? Is there any way that you could be resting or stepping on the gas supply line to the torch when you are welding or is it routed in the work area in such a manner that anything could be restricting the gas flow in the line? One final item, have you ever considered using a gas lens? They are used quite extensively in the welding of stainless piping,titanium and other exotic type alloys, they aid tremendously in distributing the gas coverage more evenly and thoroughly, I use them a bunch when I weld aluminum and with very good results. I might also suggest that you use as large a cup size as you might have available because your description of the problem suggests gas coverage problems or material contamination issues, the nozzle size certainly won't help with a material contamination issue but it will certainly help if you are experiencing a gas coverage problem. Good luck in your troubleshooting, I will be interested to hear what you possibly find. Regards, aevald

It sound like your filer rod is contaminated. I like to wipe mine off before welding. Make sure the aluminun to be welded is clean. I use a citrus degreaser and a wire brush.

Hi Dave,
I'm not a professional welder, so weight my response appropriately. However, I do a fair amount of aluminum welding, and have had similar problems, so I might be able to help.

When I get black stuff floating in the puddle, cleaning the stock and the filler rod usually help me. I like to use a cleanish stainless steel brush (used only on aluminum) to scrub the oxide off the aluminum, and acetone to remove oil or grease. Then I use aluminum cleaner (acid) on the rod (which is often oxidized, even when stored properly) and the stock, to make really really sure the oxide coating is gone. It's important that all of the water (used to rinse off the aluminum cleaner) is dried off, since it will cause porosity otherwise. If your machine has an AC balance knob, setting it for more cleaning action may also help with "pepper flakes" in the puddle.

When I see green light from the arc, I usually find the tungsten has been contaminated. Snapping the contaminated portion off and reballing it usually gets rid of the green glow.

Reducing the tungsten extension, using the largest possible nozzle, using a gas lens, adjusting flow, blocking wind, the right gas (100% Argon), etc. will all have an effect. However, I've found that most times I'm having trouble welding aluminum, it's because the aluminum or the rod is dirty.

The following links are articles I wrote about welding aluminum and contain most of what I know. Once again, I'm not a professional, and most of the people using this forum know more than I do.

http://www.artsautomotive.com/HowToWeldAluminum.htm

http://www.artsautomotive.com/CylinderHeadWelding.htm

Paul

i have found over time that the collet body that holds the tungsten streches as you tighten the back cap this makes the holes where the gas comes through become blocked i have started using a gas lens instead (these are british terms and may vary from yours)