Yet another Aluminum FNG Tig question - Thin Al Welding

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Hey all, With your input on my last thread, I now have a good confidence in welding 1/8" Aluminum now. With a sample pic here. You can see where I had bad beads, contaimation in the tip and some other things go wrong, and then I use clean areas to run fresh beads.  I can run reasonable beads with proper penetration, and in making T-joints and such I do okay (still working on that one). So the next step, logically to me, is to start going after thinner material. I picked up some 1/16" 6061 sheet, dialed down the amps to half (125A down to 60A) per the Miller Calculator's direction... And it damn near burns through the material. So first up, useful information that is constant: I have a Diversion 180. I'm using the pedal. I use Thoriated (red) tungsten 3/32" size. I'm using 1/16" 4043 rod. Now the variables: My first settings at trying 1/16" coupons with simple beads used pure argon at 15CFM and a #7 cup, my electrode stickout is about 1/8". My beads would wet very quickly and spread out to the size of a nickel. If I got near the edge of the material, it would sag and often drop or roll away. That told me I was running too hot, or possibly had too much pressure. I dialed down the amps to 45. It took a negligable amount of time longer to wet, but held the puddle a bit better. Filler got consumed almost instantly and didn't have any build up. I couldn't get any stack of dimes look, and all the metal that was added sank to the bottom side of the material. The next try was downing the gas pressure, that just caused more problems and required a tungsten sharpening. More pressure didn't change anything. I dropped the stickout to around 1/16" and did most of my attempted welding with my head perpendicular to the torch.I figured at this point, I should change to a smaller cup (#4), focus the gas a bit better, dialed the gas back down to 15CFM. Same gig, just too hot.I figured I should say screw it, let's go bottom up instead of top down. I dialed back the amps to the lowest option: 10A. Well, I got no puddle, but the arc also danced all over the place. Once I took the torch to the edge of the work piece, I got some puddle, but not enough heat to add filler. The edge itself just eroded and balled. I upped the amps to 20, and it shot right into melting the edges and everything else. I've been bouncing all over the place and I'm trying to figure out what I'm doing wrong here. So I figured I would try something really goofy. I saw the welded aluminum cans picture floating around. On 10A, with any strength of the pedal, it blows holes clean through the cans. Does anyone have some insight? I would eventually like to have the means to weld 1/32" thick aluminum, but I can't get there from here if I can't even do 1/16". Thanks all!Edit: And honest, I did try searching for subjects on this before writing this up, but didn't come up with anything applicable. Last edited by FormulaXFD; 07-10-2010 at 02:09 AM.
Reply:You have to use enough amps to get the puddle by mashing the pedal, then back off as soon as your puddle starts.  I can also tell you that I don't start at the very edge of the metal when Tigging.  If possible start away from the edge, then end up finishing your weld at the edge and be ready to back WAY OFF on the amps as you approach the edge or you'll melt it off.  My hardest fear to overcome when I first started with Tig was to really put my foot into the pedal when starting the puddle on aluminum because I always visualized the part vaporizing.  Luck!DougMiller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Originally Posted by FormulaXFDWith your input on my last thread, I now have a good confidence in welding 1/8" Aluminum now. With a sample pic here. You can see where I had bad beads, contaimation in the tip and some other things go wrong, and then I use clean areas to run fresh beads.  I can run reasonable beads with proper penetration, and in making T-joints and such I do okay (still working on that one). So the next step, logically to me, is to start going after thinner material.
Reply:There's a reason tig welding is considered the "most difficult" of the welding processes to master.Seems that the "new generation" welder wants everything "fast tracked".  Sorry, there's no silver bullet here.  No substitute for hood time.As DSW mentioned, you haven't "mastered" or even gotten decent at welding 1/8" material and already you want to move to thinner material.My advice is to learn to walk really well before you try to run.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:Well, the pain in the *** with DIY is benchmarking "good". The criteria I used was proper depth of weld for running beads - full penetration through the material without hemorrhaging material through the other side or poking filler into it. But in this case it is about hood time, so we're being redundant. Fear not, I'm not trying to take anyones job.DSW The T joint was my very first attempt at making that joint. Lots of problems on that. This workpiece was a convenient piece of scrap which is why i used it for the flats. If the rest of the beads are rubbish, then I'll stop here and go back to the drawing board and figure out what they're supposed to be and then try again. Thanks for being up front none the less.
Reply:Beads on flat plate can be tricky. In most joints you have a V, corner or gap that you are also filling. That makes the beads flatter. I'd suggest you  go ahead and move on to lap joints or T joints and start working on controlling the puddle with them. Flat plate beads are a good starting point to begin to learn to manipulate bead, but they lack some of the issues you find in real joints, like edges that want to melt back and the corners discussed above.For a start on alum tig, especially if you are doing this solo, it's not bad. I'd bet if you worked with someone who knows alum tig for an hour or so, your skills would improve drastically. Theres a lot of subtleties in working with alum. You have to be aggressive to start, yet back down fast and shift the power based on what the puddle tells you as well as compensate as the piece heats up as you move on.One thing looking back at your welds, are you melting the filler with the puddle, or the arc? Many of the beads almost look like the filler is being melted by the arc and dropped on the plate, rather than being melted by the puddle.  Some have a real difficulty understanding this concept on their own. All they see is filler melting, not how or why.Keep it up, and keep posting your practice as well as your settings and we'll help you get there eventually. You might also think about going up to the USER CP at the top left and adding your location so we know where you are. You might find someone here thats local and willing to help..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:FormulaXFD sez:".....So first up, useful information that is constant: I have a Diversion 180. I'm using the pedal. I use Thoriated (red) tungsten 3/32" size. I'm using 1/16" 4043 rod." 1-For 16 gauge-use 1/16" electrode. Presumably you're sharpening the tungsten with longitudinalgrinding-not circular, and slightly blunting or coning that 2-3 X diameter taper. (I put a teeny coneon the tapered end.)-Stick out length is a function of the cup size, vs. room in the joint, vs. gas coverage for the electrode. Too short can be a problem as is too long.2-Changing to a smaller cup-when not needed for clearance, produces less gas coverage, withmore problems. Gas lenses really do help.3-DougAustinTX sez:  "You have to use enough amps to get the puddle by mashing the pedal, then back off as soon as your puddle starts."......well.....that causes more problems:-coming on easy with the arc start, letting it get established (and often doing some form of cleaningand pre-heat-along the aluminum joint works better. -Aluminum has 3 x the heat capacity that steel does. It can take roughly 3 x as much energyto weld aluminum as steel. Additionally, aluminum spreads the heat (heat transfer), very, very quickly, producing heat distortion in thin panels and sucking the heat out of the weld fusion area.       Do to the above--after the arc is gently established as amps are being ramped up--look forsome surface wetting on the parent material--apparently you are not doing this, from your own descriptions and picture.         On thin stuff once wetting is seen--then set the rod end into the wetting. I want to see a tinyball from the rod, wetting onto the sheet. If the ball melts all the way down flush to the sheet--that'stoo much heat, for too long a time......and you've now got melt-thru. As this ball wetting happens, then add a little more rod to the ball, which is now the start of a bead.You're basically creeping up on welding the sheet stock, especially looking intently for the firstsigns of wetting. This wetting and establishing a bead without melt thru, takes lots of practice.At the same time, seeing that both sides are wetted to the sheet for edge fusion is critical.One's creeping up on it, but doing it quickly!As the weld progresses the heat is reduced. If the bead melts down flush--bingo!--melt-thru.For joints ending at the material edge--getting some decent heat soak into the stock-first, byrunning some bead away from the edge, then going to the edge-firing off at it-not into it, finishing that part, then going back to other areas, helps.....or do the edge beading first....pick your poison.4-4043 rod wets out easier than 5000 series rod (which is what's suggested on 5-6000 series sheet.) Keep practicing with that, then later try 5356 or derivatives.5-Miller Diversion--this is a very basic, entry level machine, that will make you work all the harderto do whatever. I tried out a customer's new machine, once-and was less than impressed.For the same money, a decent, bigger, used Miller or Lincoln could be had.6-What Sundowner III has said is correct.....like it or not. There's daily queries on this forumfrom folks that cannot believe that something which looks so easy, can be so daunting.Blackbird
Reply:Originally Posted by dave powelson6-What Sundowner III has said is correct.....like it or not. There's daily queries on this forumfrom folks that cannot believe that something which looks so easy, can be so daunting.
Reply:FormulaXFDaluminum fusion is not fully 'told' or perhaps better said; not completely indicated by weld bead sag or penetration of the parent metal opposite the weld area.This is not obvious without cutting and shining many sections of test coupons- but it is a fact.  The surface oxide will be lifted and often vaporized by the hot cover gases, and the AC oscillation of current flow. This surface condition is NOT always true of the inner surfaces of the two parent metal parts so bulge, sag, penetration, or weld 'show through' is not a true indication of fusion.What can happen is the fusion has a boundary layer where the two parent metal parts' edges melted into the weld puddle but the molten state was not sufficient to release the surface oxides to the surface of the weld to be washed off by cover gas.  This leaves a layer or boundary within the weld that can only be found by break bend testing OR by cutting and shining or polishing the sections of a weld to reveal if the fused area is uniform?The lack of consistency in the welds shown in your post indicate you're still reacting too coarsely to the the heat (pedal/slider) and filler rod (dip) additions to  your welds. By this I mean your movements require more practice to become "smaller" or more refined so that you're able to make smaller differences between each repeated step/puddle/droplet of your welds.  The reason this is critical is because the weld is a related rate.  If the relationship between the amperage and filler rod is not uniform the penetration or surface beads will be irregular, and the edges profiles will create a stress raiser or notch where the weld can fail over many cycle of load and unloading.  Also uniformity on the surface most often means a uniform fusion with gases formed at the root faces given adequate time to escape into the molten metal, bubble to the surface and be ejected by the cover gas.I think you've made great progress in working toward a nice bead, you have good hands and just need to work to get consistency, which is more than a surface event.  The first panel of beads is what I'd call "cold" the amount of filler compared to the amount of amperage allowing the filler to fuse/melt/flow into the parent metal- was out of balance.  By allowing less filler for the amperage shown the beads would be 'flatter' or less bulbous, less a balloon standing on the plate and more a 'Lima bean' half buried into the surface of the parent metal.  Conversely by adding more amperage the filler would have fused more 'into' the parent metal -again creating a less bulbous but still rounded bead.The last link shows a rod and two rectangular tubes or square stock and the beads are coming along nicely.  They're more fused at the edges showing a better balance between amperage and filler rod volume per step/puddle.  The ends need a little pause, cool down with reduced amperage and another dip on top of the last puddle to avoid the obvious crater sites from cooling too quickly.I think you're moving along fast and the welds are looking good, but don't be fooled if the puddles sag through that is only ONE of several indications of fusion.  Bend and break your welds to KNOW where your progress is along the path to becoming a "TIG hand".  I hope you'll remember that beautiful/consistent/exactly laid beads are the desired weld because they are the strongest, most clean and durable and that comes from being uniform and well proportioned to the parent metal.Oddly enough, thinner metal, in all alloys, is more work to weld than thicker, the reason being the level of refinement of motion required to control beads that are smaller.  We might say that the meat shop butcher can make some rapid deep cuts to get your steak prepared for the BBQ- but the brain surgeon is making some extremely small movements to accomplish his task.   Welding heavier sections can be done by a more coarse series of movements than welding thinner sections and the difference is the refinement of your hand eye coordination, which usually takes time to teach your body.Looks like you're learning a lot faster than I did, forty-some years ago!Cheers,Kevin Morin
Reply:Thanks Kevin, I appreciate the information!I actually went down to the bookstore yesterday and picked up a book that is 100% TIG and wound up learning quite a bit. So since it's all about results...The last joint shown:And after learning my electrode was too big, my flow rate too low, and I was too impatient with letting the base material's puddle sit there while it actually puddled more than just the surface....I was able to get the leg on both pieces of material to be right around 1/8" for the 1/8" thick metal. (And before anyone grinds my arse on the lap weld I did of stainless, that piece was from my fourth day with my machine :P )It also appeared that my torch angle was too conservative (tried to be as upright 90degrees as possible) and everything started working a lot better with more angle especially in the T joint. The biggest PITA with this run is noticing when the filler grows what I can only call "Tree Roots" into the metal instead of a nice wet puddle, applying just a little more and a little more pedal until it melts away. Let it simmer and clean out for a hint and then go on. The Miller calc specified 3/32" filler rod, which I did on the right half of the image. The bead is less convex, but more irregular than the 1/16" filler. So the next phase is doing it again with 3/32" filler only.(I'm detailing what I'm finding when other novices have the same problem and do searches on it)
Reply:FormulaXFD,I don't use 4043 in anything but cast because its not compatible with the 5080' series marine aluminum I use exclusively.  I do find that practicing with 4043 can be helpful at the very first few hours but it flows differently than 5356 so if you'll be welding 5086 to 6061 or 5052 to 6061 (?) I'd move to practice with 5356 as soon as possible.I would like to encourage you to practice a uniform feed of the filler with your off-hand. This is subject of countless opinions and four or five reliable methods of hand feeding, I think you should pick one and 'make it  yours'. Adding a nearly exactly equal amount of filler each puddle is key to real uniformity in hand held TIG, at least in aluminum.I've posted a set of images, somewhere here, that show one of the methods -"thumbing the rod"  but regardless of which one you choose I believe it is basic to advancing your bead.  Your new post shows good improvement and stretches of the bead you're looking for.  One thing that is important in an inside fillet as shown, is the bead is better flat across than hollow, so just a little less heat and 10-20% more filler rod per step would bring the surface up to a more uniform 45 degree face instead of the slight hollow you show.A hollow face in aluminum can provide a stress crack source at the toe or top of the weld if the two parts or parent metal are flexed back and forth- that means the weld may fail at the edge of the Heat Affected Zone due to the slight concavity at the fusion line of the edges of the weld.  This would usually be a premature failure that is overcome if the weld is just a little more 'full'.Cheers,Kevin Morin
Reply:Thanks again Kevin! The 4043 I have is what the supply shop sold me (all they stocked). On Monday I ordered a complete kit of 1lb bundles of 5356 (1/16 to 1/8) and some replenishment of 4043 in the same ranges. I've been at this pretty much every day since I got the machine last month, so hopefully I'll keep the rate of learning up.