Question about tigging an aluminum alloy

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Hello, I am new to the forum, had a question and thought I might ask...Anyways I have a Miller Tig with argon gas feed, I am trying to weld these injector bungs (I believe to be 6061 aluminum) onto this supercharger intake (that I was told was L25 aluminum, which is erupoean spec), I also had a company tell me that they think the alloy may be 319/356T6 or 808. Anyways so I am not that experienced, I have welded some aluminum before (generally I have a hard time with it), but this I just cannot seem to weld it properly, I got a part welded on but I am having issues, beginning to jack up the injector bungs, etc. It just seems that I am not doing something right so I thought I would ask you guys on some advice...seems I have a hard time getting a puddle to form and when I go to dip the filler rod into it the filler rod just balls up and doesn't want to stick...Anyways I have it set to AC, the tungsten is sharpened to a point (though I heard I may want to ball up the tungsten when welding aluminum to spread the gas around more, haven't tried it yet but I do now have a ball of aluminum hanging off the end of it if thats the same). Also what do you guys do clean off the aluminum good? Seems I may be having a problem with the metal being dirty...The tig is a Miller DX, and the filler rod I was using was aluminum labeled as ER4041 which says recommended for welding 3003, 3004, 5052, 6061, 6063, and casting allows 43, 355, 356, and 214. I remember at the sore there was another kind of aluminum filler rod labeled as something else, maybe I am not using the proper filler rod as well?Thanks any help is greatly appreatiated! -Matt
Reply:if you cannot get a puddle to form on the housing try preheating it. alum. is a very good conductor remember so it is sucking the heat away faster than you can put it in. Just something you could try i have had to do it on race car rims.
Reply:Awsome thanks for the reply! What method do you do to preheat it? Like a propane torch?Oh btw I didn't have the pulser on, I just had it sending it out steadily...
Reply:Yeah , a propane torch will work, but it will take some time. If you have oxy/ acet. it would be better. Also , check your settings on the frequency balance. I don't remember where it should be for a starting point, but it basically controls the "cleaning"  and  "penetration", more of one, less of the other. Castings are generally harder to weld. Good luck. You didn't mention which electrode type you are using. If you are not using an inverter, you do want to have a ball on the tip, but you can get away with not having one, just a little harder to weld. I personally have good results with 2% thoriated, although I have been wanting to try one of the newer types.Tony
Reply:what kind of miller tig and how thick of alum you trying to weld?ChuckASME Pressure Vessel welder
Reply:i personally like to have my balance at about 71 and dont vary maybe three or four in either direction.  not having the pulse on should be better; like you said sending it out steady. and thats what you need on those big pieces.  if you are concerned about being clean try some acetone or denatured alcohol in spray bottle. be sure there are NO open flames so you dont loose your eyebrows or something worse. let it evaporate before you go back to welding. and always use a clean wire brush, on that hasnt been used on any other metals.
Reply:I  was doing some similar welding this weekend and I noticed a couple of things.1. Alluminum likes amperage, allot. I was welding 1/8" to 3/16" and had the machine set to 155 amps constant, since I couldn't use the foot pedal. 2. It has to be clean. A Stainless Steel cup brush and assorted wood handled SS wire brushes were required to clean through the oxides. I would follow up with a brushing of acetone. 3. The alluminum on the tungsteon is a no go. The least bit of contamination would completely mess up the process. 4. keep the filler near the weld area. If you pull the filler back into open air it tended to foul the weld when reinserted into the puddle.5. be quick with the dab to the puddle. Don't fart around, drop the rod in the puddle and pull back, repeat.  These are things I learnd quickly Saturday, they might not be the right thing to do but it did work for me.  Also I set my A/C balance to 6, argon CFH to 20.Millermatic 251Century 180 migSpectrum 625 Syncrowave 250DX
Reply:Thanks a lot for the advice I will try this out! Someone mentioned to me that I may want to try and use 4043 filler rod instead of my ER4041 filler rod, does this sound like a good idea?
Reply:A word to the wise : IF your aluminum is about 1/8th inch or thicker , do not use straight  argon. You need Helium. Maybe straight helium, or a mix of about 80% helium & a little argon, just for cleaning action , during the weld .  Argon is too dense for the alum , whem the alum is more than about.1" -.125 " (1/8th) . Argon is 10 (ten) times denser  than aluminum. Remember , aluminum needs the heat  NOW  - melt it quick & weld it quick , or it'll just slowly get too hot and finally drop out ,leaving you with a hole ,not a weld. always use a balled tip on tungsten ,clean &shiny  . Only time you don't need it balled is if you're welding aluminum that is only 1/32" thick , or thinner & maybe using an .020 tungsten .
Reply:I don't know crap about the fillers yet. I used what the guy at the welders supply sold me for what he thought the material might be, it worked well so....Millermatic 251Century 180 migSpectrum 625 Syncrowave 250DX