problems with TIGing aluminum

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I have researched and tried everything that i can think of for the past 6 months but i am still having problems. I have a miller syncrowave 180-sd and i have been tig welding everyday for well over a year now. i typically try to weld 16 gauge 6061 aluminum with er4043 filler rod. I can start a nice shiny puddle and maintain it with no problem but then as soon as i touch the filler rod the weld turns to black/gray garbage. i always clean the hell out of the weldment and the filler rod, ive used sharpened and balled 2% and pure tungsten, ive used different cleaning methods and solvents, ive tried low and high amperage, ive adjusted the cleaning and penetration all across the board. its always the same thing, i always get a contaminated weld. it seems like it happens more when welding butted peices. when i run a bead in the middle of a single piece i have less problems. i have also bought a different brand of filler rod and i get the same thing. i have not yet ventured away from er4043 because the guys at airgas told me not to. what am i doing wrong? i can weld mild steel and stainless like a pro but aluminum just wont cooperate. please help, i will appreciate it immensely.another question which i think i know but i want to make sure. this is my first tig welder and i just want to verify that the ac arc is supposed to somewhat pulse. its like it is rougher than a dc arc. is this correct? after trying so many things i start to wonder if my machine is messed up.Last edited by turboitall; 06-23-2009 at 03:04 AM.
Reply:Onlyist thing I can come up with is when dipping the rod you are hitting the electrode as well?
Reply:I have the Synchro 180 SD and it gave me quite a fit when welding Al.  The high freq. is on continuously in AC mode so you do get  somewhat of a pulsing sensation, more of what I call a 60 Hz hum.  The problem I had was with the hi-freq contacts, which caused eratic behavior of the arc that would "jump" to the filler no matter what angle I seemed to hold the torch at.  The contact gap was set to .012 factory spec. and Miller Tech advised changing it to .008.  I played with it until I got a very stable arc and ended up at .006.  Also, there was no way I could get any decent welds with balled pure tungsten.  I had to go to the sharpened 2% thoriated with the tip flattened to about 1/3 the electrode diameter.  Hope some of this helps.
Reply:nope, not hitting the electrode. it turns into something like burnt charcoal and its very porous. the end of the filler rod does the same thing and i can usually tap it on the weldment to break it off. in the beginning i thought it was getting contaminated but i clean everything like a madman and it still happens.
Reply:Originally Posted by GerryRI have the Synchro 180 SD and it gave me quite a fit when welding Al.  The high freq. is on continuously in AC mode so you do get  somewhat of a pulsing sensation, more of what I call a 60 Hz hum.  The problem I had was with the hi-freq contacts, which caused eratic behavior of the arc that would "jump" to the filler no matter what angle I seemed to hold the torch at.  The contact gap was set to .012 factory spec. and Miller Tech advised changing it to .008.  I played with it until I got a very stable arc and ended up at .006.  Also, there was no way I could get any decent welds with balled pure tungsten.  I had to go to the sharpened 2% thoriated with the tip flattened to about 1/3 the electrode diameter.  Hope some of this helps.
Reply:Are you taking your filler right out of a hermetically sealed package?  Have you actually checked the stamp on the end of the filler?  (That one sounds stupid, but on more than one occasion I have mixed in my SS electrodes with aluminum, and it does exactly as you've described.)  Have you tried stripping the outside of the filler with 3m paper and wiping it down with acetone?
Reply:Originally Posted by turboitalli have had better results with sharpened 2% as well. i taught myself everything so im not good with the terms. i think you might be talking about a setting in the machine (hopefully). if so would you mind sending me a message on how to adjust it?
Reply:Originally Posted by SupeAre you taking your filler right out of a hermetically sealed package?  Have you actually checked the stamp on the end of the filler?  (That one sounds stupid, but on more than one occasion I have mixed in my SS electrodes with aluminum, and it does exactly as you've described.)  Have you tried stripping the outside of the filler with 3m paper and wiping it down with acetone?
Reply:turbotail,Sounds like a gas issue to me.  Are you sure you're flowing enough covering gas?  Have you checked for a leak in your gas feed?  Will the machine hold gas pressure for awhile after you have shut off the tank valve?Try running a bead across a piece of aluminum plate without filler.  If you're still getting black spots, the problem is gas related, not HF problems.You could also be getting some disruption in gas coverage if there's a slight breeze in the welding area.  Aluminum is "more sensitive" to gas coverage than steel.When using filler, if you're removing it from the gas envelope after feeding it's getting contaminated.  Need to keep it in the gas coverage but far enough away that it doesn't melt before you get to the puddle.Posting up a couple pics would help us help you identify the problem.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Originally Posted by Fat BastardOnlyist thing I can come up with is when dipping the rod you are hitting the electrode as well?
Reply:Originally Posted by SundownIIIturbotail,Sounds like a gas issue to me.  Are you sure you're flowing enough covering gas?  Have you checked for a leak in your gas feed?  Will the machine hold gas pressure for awhile after you have shut off the tank valve?When using filler, if you're removing it from the gas envelope after feeding it's getting contaminated.  Need to keep it in the gas coverage but far enough away that it doesn't melt before you get to the puddle.Posting up a couple pics would help us help you identify the problem.
Reply:im flowing about 18-20 cfm with a #6 cup. i dont know what a gas lense collet body is. i have a weldcraft air cooled torch. the tungsten is always nice and clean. i can weld a nice bead without filler but welding two pieces together without filler isnt very practical. i dont think its a gas flow issue. after i close the tank and turn the machine off the lines lose pressure after 30 minutes to an hour.
Reply:turboitail,Even more convinced now that it's a technique issue.  Aluminum is "a lot" more sensitive to contamination than steel.  I suspect you're allowing the filler to become contaminated by removing it from the gas envelope.A gas lens replaces the standard collet body in the front end of your torch.  It will require the use of different cups than those used with the standard collet body.  Much better gas flow over the weld bead.  Try starting out with a #7 cup.If your arc (in AC) is not "dancing all over the place", it's unlikely that HF is your problem.  I've never seen points being set wrong cause "black spots/soot" in an aluminum bead.Kinda extreme, but try cleaning the filler with a scotchbright pad and then wiping it down with alcohol or acetone.  I'd also pick up a pound or so of 5356 and give it a whirl.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Your lines should not loose pressure in 30 min-hour. Even over night they should not lose pressure once tank is shut off. 18-20 cfm is a bit high. Usually I run aound 15 cfm with regular collet body or 12 with gas lense. Pull your tungsten out and tighten the torch back up then put your thumb over the cup and hit the pedal to get the gas to flow. It shouldn't leak anywhere and should stay in there for a while till you pull your thumb off cup. Too much pressure can cause erratic arc. I have had hose come off in torch body and lost pressure at cup even though the rest of lines were sealed well.
Reply:S obcessed,If your system holds pressure overnight, with the gas turned off, you've got a rare system.If he had a loose gas line the tungsten would be getting contaminated.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Originally Posted by SundownIIIturboitail,Even more convinced now that it's a technique issue.  Aluminum is "a lot" more sensitive to contamination than steel.  I suspect you're allowing the filler to become contaminated by removing it from the gas envelope.A gas lens replaces the standard collet body in the front end of your torch.  It will require the use of different cups than those used with the standard collet body.  Much better gas flow over the weld bead.  Try starting out with a #7 cup.If your arc (in AC) is not "dancing all over the place", it's unlikely that HF is your problem.  I've never seen points being set wrong cause "black spots/soot" in an aluminum bead.Kinda extreme, but try cleaning the filler with a scotchbright pad and then wiping it down with alcohol or acetone.  I'd also pick up a pound or so of 5356 and give it a whirl.
Reply:I feel for ya Turbo, I believe I have been haveing the same problem.  I've been starting to wonder if the humidity has anything to do with it?  Last night I was messing around with my sync 200 and was haveing troubles with floaters and swollen gray blobs.  I can run a bead without filler on dirty alum just fine, but try to add filler and I get major problems.  I have cleaned my filler repeatedly with no change what so ever.  I'm kinda interested in this whole contact adjusting thing.  Not sure if my machine has them or not, but the etched area around my welds has all but vanished and changing the balance has not really shown any difference.  Been having trouble keeping the arc where I want it also.  Would a machine that is only 3 or so years old have HF contact problems?  I did some great work with it this winter and before that also, so I don't believe it is a technique problem.
Reply:turboitail,You didn't mention where you had the balance set on your machine.  Try setting it at 7-8.  This will give you more DC- (heat).If you're cleaning the aluminum properly (SS brush) you don't need a whole lot of "cleaning action".  On my Sync 250, I'm usually at around 8 on the balance control.  Gives me a small oxide layer beside the bead.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:great news! you guys are awesome. i adjusted the contact gaps to .008 and i set the balance to 7. i cleaned the aluminum like usual with a scotch brite pad and acetone. i also stepped up my cup size from a 6 to a 7. then i proceeded to weld without any major issues. gas flow was about 17-18 cfm.here is before with the gray swollen blob burns:and after i made the adjustments. i still need to practice on my aluminum skills but its ALOT better and easier now:thank you guys so much for the advice. i cant tell you how happy i am about this.
Reply:also, i tried to keep the filler rod in the gas envelope more and i think that may have helped too. all i have to do now is work on not removing the filler rod too far. thanks again guys.
Reply:Originally Posted by turboitallalso, i tried to keep the filler rod in the gas envelope more and i think that may have helped too. all i have to do now is work on not removing the filler rod too far. thanks again guys.
Reply:How much stick out are you running? It's really easy on AL to have run to much stickout in an effort to see what you are doing under the leading edge of your cup Too much stick out equals poor gas coverage which is most likely your problem. A gas lens will help with this. The decrease in turbulence will allow you to bump your gas flow up a bit and run a longer stick without fear of contamination.  Being able to see what you are doing is priceless.
Reply:I left for a few hours and you got your problem solved.   Glad you did.  I went through the same frustrating series of events and was happy to get through it.