Tig welding a T joint on thin aluminum

admin

I have a Miller Syncrowave 250 tig welder and one thing that I have never seemed to do well is welding say a "T" joint or corner joint on aluminum. I attached a pic showing a corner joint (towards the bottom of the picture) of .100 thick 6061 welded together. I ended up putting tons of heat to melt the aluminum to be able to flow a bead and even then the bead looks like crapola. In the same picture you can see some of my welds joining 2 more pieces of flat aluminum together and also just laying some flat beads. For the most part I think my beads on flat surfaces come out pretty decent. When I weld the T joint, the shielding gas seems to accumulate in the joint area and the whole area seems to become one big plasma field. The situation gets even worse if you try to go back and weld say a 1 inch gap (non welded area) between beads. That gap between beads just traps all of the shield gas and the whole thing wants to just pop pop pop. Can't even get in there to lay a bead anymore, completely unstable. Tried argon, argon/helium, and helium alone, same result. I flow about 10-15 cfm. I'm using a 3/32  2% thoriated tungsten electrode. I also tried turning the ac balance from max cleaning to max penetration...no difference. If I turn the work piece slightly down so the gas doesn't accumulate, I can start welding again so it seems like it has something to do with the welding gas getting trapped in there. Any and all help would be appreciated. This is making me crazy!
Reply:My Syncro 250 seems to like pure tungsten for aluminum...Miller Dynasty 200DXMiller 252 Miller 250xMiller Syncrowave 250Miller AEAD200 LegendMiller 375 Xtreme plasmaLincoln WeldPak 100Victor O/A
Reply:Well if it were me I would use a balance of about 70%, sharpen my thoriated tungsten, pull out at least the diameter of the nozzle, push the tungsten in tight, start an arc and hold the arc until it melts the joint to the root and then not rush the weld. A tee fillet takes much more heat to weld. The material mass and heat sinking is just much more. Pound that pedal and murderize that joint.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:One big error guys often have when trying to weld alum is they try a creep up on the heat like they can with steel. With alum you have to jack up the maps and hammer the pedal to get the bead started fast, then back off the pedal and fly.  I personally prefer to run lanthanated ( blue) and run a point vs green and a ball. The lanthanated also usually lest me step down one tungsten size roughly. With that I'd be running 3/32" ground to a blunt point..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Seems like your having the same issue I had when learning to weld aluminum, as the other said slam the pedal to get a mirror puddle started and go, once your going adjust your amps. I've found that it's easier to weld aluminum by starting from one of your tacks. My Tungsten choice is also 2% lanthanated
Reply:Thanks for the reply guys! I've tried the lanthanted electrodes but had the same results.  Hammer and murder the "go" pedal! I like that. I'll give it a shot tonight. Thanks again for the advice!
Reply:What is your amps set at?Unstable arc between beads says too low amperage too me. Filling between two beads should be super easy for you.My transformer based tig wanders around till the amps comes up - which is not even noticed if the pedal gets floored quickly.Btw, I've never heard someone say trapping shielding gas is bad - imagine how hard it would be to weld in a groove joint if that were the case?Edit: I should add, equipment malfunction and bad gas are always an option.Also, my machine has a very large shielding gas surge on starts, which can cause some weird erratic arc behavior - so I tap the pedal to start the post flow timer, then I weld.Last edited by MinnesotaDave; 01-16-2014 at 10:33 AM.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Hey CV.I have a Syncrowave 250. I have been trying to master the aluminum T joint also. Here's how I do it better, still not as good as the pros.Aluminum is 1/8" and filler is either 1/16" or 3/32". Cleaning set at 70. Use 2% lanthanted 3/32 ground to a dull point. Argon 15 CFH. Pull the tungsten out about 1/4". Point the tungsten about 60 degrees to the travel so the gas is moving ahead of you. Amps are at 200. As said already, floor it and start moving. Let up on the pedal as you move along and the heat is accumulating.Maybe this should be easy, but I have burnt a lot of aluminum trying to get the timing right. Good luck. I'd say post more pictures, but if yours look like a lot of mine, I wouldn't want to show it yet!Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:Just looking through and reading some of your issues. Don't get down on yourself, a "T" joint, doing a 2F with aluminum is harder than people think it would be. Especially if your looking for an acceptable, proper penetration. I just finished running weld procedures on 6061 to 5083 and then 1100 to 1100. The 1100 was more of a challenge due to the higher thermal conductivity of the grade. It will help if you set your AC balanced favored to the PENETRATION side. We used a 1/8" Zirconiated tungsten. Like previously mentioned, have more stickout with the tungsten than normal. Start with hitting the heat into the metals high to get your puddle established. Once you puddle is going, back down your heat slightly. Be sure to not use to large of a diameter of filler as you don't want the filler puddle to create to much heat soak. Good luck and stay at it!!
Reply:Originally Posted by AKmudMy Syncro 250 seems to like pure tungsten for aluminum...
Reply:Now I need to mention this because it is overlooked so often.If you practice on a scrap of flat plate you have set yourself up for failure.Here is why.With aluminum the size of the weldment determines how much heat /amperage input will be needed to get that plate to melt.The larger the weldment the more heat that will be needed.So you get a flat scrap and start to lay down a bead. The plate starts to heat up and then each bead you start the amperage will need adjustment either through the foot pedal or on the machine.Or both.Finally you will start to burn through the plate.If you really want to know what is going on, take the time to tack some T joints together on same sized and same thickness plates. You need to be welding down a groove or a joint.That is what many welding schools to to prepare the students. They spend the money to provide same sized welding coupons to practice welding on. Not just any old scraps like some Jr. colleges do.That will not help the student.AWS certified welding inspectorAWS certified welder
Reply:What size cup are you using? Almost sounds like you have too much flow. Try turning the flow down a bit or using a larger cup. With steel high flow rates usually won't hurt, but with aluminum I've seen problems with too much.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Originally Posted by SquirmyPugWhat size cup are you using? Almost sounds like you have too much flow. Try turning the flow down a bit or using a larger cup. With steel high flow rates usually won't hurt, but with aluminum I've seen problems with too much.
Reply:Good to hear! The fun thing about welding is you continuously learn something every day!
Reply:Glad to hear you got it One point though, your meter reading is cfh (cubic feet per hour) not cfm.Your meter may be off a little, I recommend you buy a slip on meter to check your actual flow at the tip. I use mine at the beginning of every day that I tig.It just slips over your cold tig cup and checks your flow - it will eliminate guesswork when checking for problems in the future. I use it on my mig too (flip up the drive roller).Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Glad i could help, too much flow is often overlooked as a problem with welding aluminum. Its hard to form a puddle and usually has a loud arc with too muchAirco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Thank you thank you thank you for you help! I appreciate it!Todd