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This is the byproduct of me having way to much time on my hands, and noticing that about every week the same questions pop up. Hopefully this can shed some light about the mystery and general misconceptions about TIG welding of aluminum.Polarity: AC current consists of a positive and negative portion, and alternates very rapidly between the two. This produces the "buzzing" sound that you hear, and what contributes to the nature of the AC arc. The AC balance control determines how much time is spend on either portion, a value higher on the negative side will giver better penetration and arc stability with decreased cleaning action, and vice-versa. The positive portion of the wave (electrode positive) puts about 70% of the heat generated into the tungsten, this causes the tungsten to melt and beings to form a ball at the end. This portion of the wave is also what produces the cleaning action, in which ions bombard the surface of the material, removing some surface contaminates. DCEP can be used for welding of very thin aluminum but the tungsten will rapidly overheat.The negative portion of the wave (electrode negative) puts about 70% of the heat generated into the workpiece, yielding much better penetration. This also enables the tungsten to better retain a point which makes the arc more stable and easier to control. This part does not offer any cleaning action. DCEN welding can be done on aluminum but it requires removal of all surface contaminates and generally done with helium shielding gas. (I dont know why, if any one can shed some light on this than im all ears)Shielding Gas: 100% Argon is the most common, while mixtures of Ar and He can be used to achieve greater heat input. Argon is preferred because it is cheaper than He, very dense (better cleaning action) and produces a stable arc. Any mixture containing O2 or CO2 cannot be used because of the rapid formation of aluminum oxides, along with the rapid erosion of the tungsten.Tungsten: The electrodes used on AC welding vary greatly with personal preference, but I do not know of any commonly found electrode that cannot be used. Some of the more popular ones include 2% ceriated, 2% thoriated, 1.5% lanthinated and pure tungsten. Pure tungsten is not required for use on any machine, in fact most inverter machines will not proper functionally with pure tungsten. Forming a ball on the end of the electrode is not necessary, often it is preferred to weld with a slightly blunted point. If the ball grows too large and the arc seems unstable, stop welding and regrind the tungsten. If it continues, either decrease amperage or go to a larger tungsten diameter. AC Controls: Older machines will likely have a simple balance control which was explained earlier. Newer inverter machines typically have an additional frequency control. This allows the user to adjust the amount of times (per second) that the arc switches from EP-EN. The standard is 60Hz, but increasing this ,typically >120Hz will stabilize the arc, making it "stiffer" and increasing penetration while reducing the width of the weld pool.This is by no means the definitive guide, obviously I hardly even touched the surface. If you have something to add, do me a favor and just make it easy to read but feel free to add it in here. The goal is to make this a one-stop-shop for aluminum. If you disagree with something, PM me and we'll work it out.That's all for now, more to come tomorrow.Have we all gone mad?
Reply:Cleaning: Welding of aluminum is made difficult because of how rapidly it can form an oxide layer on its surface. While this is what makes it so resistant to corrosion, this layer must be removed prior to welding. This can occur in a number of ways, either by mechanical cleaning like a wirebrush or abrasive pad; chemical cleaning using a variety of industrial solvents or electrically by the bombardment of ions.Stainless steel wirebrushes are a good choice, as they are both very effective and cheap. Care should be taken to prevent contamination of the brush (either from oil, dirt or rust), which could impart these contaminates onto the material and into the weld. Powered wire wheels should be avoided as these have a tendency to smear the material and further trap contaminates instead of removing them. Steel brushes should be avoided if possible because they can leave behind iron oxides (rust) on the material.Wiping with a solvent such as acetone, denatured alcohol, or others is a good idea, but make sure that all solvent has been evaporated or removed from the weld joint before an arc is struck to avoid the possibility of dangerous fumes or fire. However these solvents will not remove the oxide layer, only excess oil or dirt.Abrasive mediums like 3M pads, sanding or grinding wheels or stripper wheels work well for removing heavy contamination like is often found on castings or parts that have been in service. These will remove surface oxides as well, but can also smear the material if to much pressure is applied.How clean is good enough? I would be lying if I said Ive never successfully welded material that had heavy oxides on the surface, or had some leftover dirt that got pulled into the weld. Ultimately the decision is yours to make, but keep in mind that the cleaner the material, the easier it will be to weld, lower chance that cracks will form and overall leads to a better quality weld.Have we all gone mad?
Reply:Common problems with welding:I cannot get a puddle to form: Possibly not enough amperage, aluminum requires more amps than steel does for the same thickness material. You might also be on DCEN instead of AC, this will generally create a "skin" over the puddle making it hard to distinguish from the base metal. Your balance might also need to be adjusted, as a value high on the EP side will reduce the heat into the weld pool and a value high on EN might not remove enough oxides to allow the puddle to be seen.Its also possible that you have inadequate shielding gas coverage, this allows atmosphere to reach to weld pool and rapidly forms a thick oxide layer which can make welding impossible. Increase gas flow, or consider using a gas lens which will provide better coverage than a standard collet nozzle.My tungsten keeps falling off: Amperage is to high, or your on DCEP instead of AC. Find a way to reduce the amps needed, switch to a larger tungsten, or increase the balance control more towards the EN side.My filler keeps balling up: This is because the filler is kept to close to the arc, either switch to a larger diameter filler wire or keep it farther away from the arc. Balled up filler wire should be cut off, because it tends to oxidize and if added to the weld pool will make further welding difficult.Have we all gone mad?
Reply:Originally Posted by sn0border88How clean is good enough? I would be lying if I said Ive never successfully welded material that had heavy oxides on the surface, or had some leftover dirt that got pulled into the weld. Ultimately the decision is yours to make, but keep in mind that the cleaner the material, the easier it will be to weld, lower chance that cracks will form and overall leads to a better quality weld.
Reply:You shouldnt see any black contaminates if the material is *near* perfectly clean, only time you would see that is if it was not clean to start with. If im working with new material, I typically run 85-90% EN. A quick swipe of a wirebrush after everything is tacked up is all I would ever do in that case, and you wont see any specs in the weld either.I think you misunderstood what I said about 70%. This is not a point where the EP portion becomes ineffective, as70% EN is a pretty common setting giving good penetration and tungsten life without sacrificing cleaning action. Dont make the mistake of thinking that you can run 95% EP and just blast through whatever you want; regardless of your balance the material has to be fairly free to start with.What I was referring too was that in DCEN welding, 70% of the heat generated is put into the workpiece. Opposite for DCEP welding, which is why the tungsten overheats so rapidly on that polarity.Last edited by sn0border88; 03-13-2011 at 05:30 PM.Have we all gone mad?
Reply:Snowboarder88,Thanks for a valuable topic. After wading through all the advertising hyperbole and half-truths, you've cleared up a lot. Short question - I've been trying to draw the line (like I initially thought DiabolicZ was getting ready to ask about) on the polarity balance features between different models. As a practical consideration (3/8" aluminum or less) and assuming money is somewhat a factor, based on what you know looking back, would the price difference between a 70-30% polarity balance machine and an 85-15% range be something you wish you would have sprung for? I'm not looking for any kind of absolute standard, but I'm trying to make one purchase that covers most jobs, even if I have to burn extra time and energy getting all the impurities of the surface. Any thought as to what else you might be giving up with the cheaper model?
Reply:I think I know what you're getting at, and its a valid question, however I dont think I can answer it well. In my experience, knowing how to adjust the AC balance to suit the task at hand is a very important part of welding. But these adjustments need to take into consideration many factors, such as tungsten, waveform and more importantly machine type.Inverter machines seem to benefit more from being able to run in the 80-90% DCEN range than transformers because by design they tend to ball the tungsten less. Transformers dont seem to run much different from 70-85%, usually if you push them too far with blended tungstens you will start to see splitting or cracking. 70-75% seems to be the max where you can keep a good ball formed.Different tungstens also react differently to changes in balance, thoriated tends to be the most prone to splitting, followed by ceriated and then lanthinated. With that being said, I tend to always use ceriated as it seems to hold its shape best on my machines, but im sure others would be quick to disagree.So is it worth it do pay up for a machine that is capable of 85% EN? If the choice was between a transformer with 70% and an inverter with 85%, no question go with the 85% machine. If both machines were transformers, then I would be hard pressed to convince myself to pay up for that little extra.Have we all gone mad?
Reply:Excellent info here. Just perfect for a welding forum. Thank you for sharing your knowledge with the rest of us. This is virgin territory for most and exactly why we are here usually. This is one of the best posts I have EVER witnessed so please accept my thanks this is VERY unselfish on your part.
Reply:Boarder:My helmets off to you.Nice work providing that editorial for those less knowledgeable on this subject.You rock, Dude!Measure twice, cut once.Millermatic 211Millermatic 251Miller Dynasty 200DXESAB O/A Set-up
Reply:I have spool gun for my miller 212 for alu.no problems there and have tig gun powered by my ac/dc stick machine for mild steel, no problems there, was wondering if possible to do alu. on the a/c side of my stick machine? prolly a dumb ? but Idon't know and appreciate any input good and bad thank's alot and keep your rod's dry.
Reply:Possible yes, but not as is. You would need a HF module that produces a high-freq current inline with your power source. As the AC wave switches between EN and EP there is a brief transition point that involves very low voltages, making it very hard for the arc to keep bridging the gap between the tungsten and the work. What the HF box does it provides a low amp - high volt current that allows the arc to stay lit through this transition period. Some machines have refined the wave to the point that they no longer require continuous HF current, only for arc initiation. But your stick welder is not one of them I would advise against it, and save your money and headaches for a dedicated TIG machine.Have we all gone mad?
Reply:I have seen the 2% thoriated tungsten to "spit" and show up in x-rays. 2% zirconium tungsten did not have this issue and it is what I use on all aluminum projects I do.
Reply:[ame]http://www.youtube.com/watch?v=vWNZioJ_FOc[/ame] thermal arc 252i - millermatic 350P - miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs - Hypertherm 1250 G3
Reply:Thank you ,sn0border, this will be a much needed and usefull thread!
Reply:When your screwed up like me, MIG IT!!!!! Spool gun ready!!!!! Lincoln Power Mig 216Lincoln AC/DC-225/125Miller 625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita Baileigh NRA Life Member
Reply:Do I assume you are spamming a sticky?Last edited by zapster; 06-06-2012 at 06:04 PM.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:Originally Posted by shovelonDo I assume you are spamming a sticky?
Reply:Originally Posted by shovelonDo I assume you are spamming a sticky?
Reply:Just thought I would add that there really is really little use for a machine that has a balance range. 120Hz will stabilize the arc, making it "stiffer" and increasing penetration while reducing the width of the weld pool.This is by no means the definitive guide, obviously I hardly even touched the surface. If you have something to add, do me a favor and just make it easy to read but feel free to add it in here. The goal is to make this a one-stop-shop for aluminum. If you disagree with something, PM me and we'll work it out.That's all for now, more to come tomorrow.
Reply:Originally Posted by Donald BranscomYou have some misinformation.Helium gas is used for welding aluminum weldments that are thicker than 1/4 inch.Different gasses do different things.Argon keeps a stable arc and acts to keep oxygen away.Helium gets better penetration on thick weldments.Co2 gas helps to cool the weld and to sheild the weld.You need to look up what each gas is used for. It's purpose.ALSO: On a full box of tungsten if you read it it tells you what each type of tungsten is used for and why.Just keep reading more stuff. But do not rely on what people tell you. Look it up yourself.
Reply:I don't know whether I have a transformer or inverter sort machine.the manual says that provided one it is a transformer machine then I may as well unite the sensing wire to a 115v melded association inside the welder and the fan association being the coveted spot,however the wiring plan basically indicates the sensing wire being associated with the work side or negative side of the welding machine
Reply:Well done,The information that was given was great for the uninformed....Way to go.....
Reply:I wish I knew about aluminum SMAW before I bought the wrong TIG welder!Be wary of The Numbers: Figures don't lie,. but liars can figure.Welders:2008 Lincoln 140 GMAW&FCAW2012 HF 165 'toy' GTAW&SMAW1970's Cobbled together O/A
Reply:It may not be total a aluminum casting, you could check the content of the base metal and change you filler rod if needed, keep your heat as low as possible. SwannyLast edited by blueweld59; 11-28-2013 at 09:01 PM.Reason: punctuation
Reply:Originally Posted by sn0border88This is the byproduct of me having way to much time on my hands, and noticing that about every week the same questions pop up. Hopefully this can shed some light about the mystery and general misconceptions about TIG welding of aluminum.Polarity: AC current consists of a positive and negative portion, and alternates very rapidly between the two. This produces the "buzzing" sound that you hear, and what contributes to the nature of the AC arc. The AC balance control determines how much time is spend on either portion, a value higher on the negative side will giver better penetration and arc stability with decreased cleaning action, and vice-versa. The positive portion of the wave (electrode positive) puts about 70% of the heat generated into the tungsten, this causes the tungsten to melt and beings to form a ball at the end. This portion of the wave is also what produces the cleaning action, in which ions bombard the surface of the material, removing some surface contaminates. DCEP can be used for welding of very thin aluminum but the tungsten will rapidly overheat.The negative portion of the wave (electrode negative) puts about 70% of the heat generated into the workpiece, yielding much better penetration. This also enables the tungsten to better retain a point which makes the arc more stable and easier to control. This part does not offer any cleaning action. DCEN welding can be done on aluminum but it requires removal of all surface contaminates and generally done with helium shielding gas. (I dont know why, if any one can shed some light on this than im all ears)Shielding Gas: 100% Argon is the most common, while mixtures of Ar and He can be used to achieve greater heat input. Argon is preferred because it is cheaper than He, very dense (better cleaning action) and produces a stable arc. Any mixture containing O2 or CO2 cannot be used because of the rapid formation of aluminum oxides, along with the rapid erosion of the tungsten.Tungsten: The electrodes used on AC welding vary greatly with personal preference, but I do not know of any commonly found electrode that cannot be used. Some of the more popular ones include 2% ceriated, 2% thoriated, 1.5% lanthinated and pure tungsten. Pure tungsten is not required for use on any machine, in fact most inverter machines will not proper functionally with pure tungsten. Forming a ball on the end of the electrode is not necessary, often it is preferred to weld with a slightly blunted point. If the ball grows too large and the arc seems unstable, stop welding and regrind the tungsten. If it continues, either decrease amperage or go to a larger tungsten diameter. AC Controls: Older machines will likely have a simple balance control which was explained earlier. Newer inverter machines typically have an additional frequency control. This allows the user to adjust the amount of times (per second) that the arc switches from EP-EN. The standard is 60Hz, but increasing this ,typically >120Hz will stabilize the arc, making it "stiffer" and increasing penetration while reducing the width of the weld pool.This is by no means the definitive guide, obviously I hardly even touched the surface. If you have something to add, do me a favor and just make it easy to read but feel free to add it in here. The goal is to make this a one-stop-shop for aluminum. If you disagree with something, PM me and we'll work it out.That's all for now, more to come tomorrow.
Reply:Originally Posted by nmaineronI attempted to weld my transmission case with the HI FREQ box connected to my AC/DC machine.I had no problem as far as function however I had big problems with cracking after welding.I preheated the case with a propane torch a few times for cleaning and to expose any cracks.Cracks were identified and welded successfully.I had two spots where the case `was worn through.I managed to weld these spots up by building up the edges and had good solid cover.The cracks started after the the holes were filled.Initially they ran parallel with the weld but outside of the fillet.I tried to gouge the crack and fill it but after I did that, new cracks appeared and ran perpendicular and were very pronounced,so much so that I feel that there is too much to repair. i would appreciate opinions.Thanks,Ron
Reply:Originally Posted by mike837goI wish I knew about aluminum SMAW before I bought the wrong TIG welder!
Reply:Originally Posted by shovelonNot to be snipy, but your post contains some misinformation.1. Not all boxed tungstens goes into detail for usage(chinese).2. Co2 is not used with tig welding, let alone alum tig.3. Helium can be used on all thicknesses of alum if so desired. Smaller tig machines can benefit if hotter weld is needed. 100% helium is used in DCEN welding of alum of all thicknesses.
Reply:Originally Posted by Donald BranscomWhich TIG welder did you purchase?You can weld aluminum with SMAW but it has constraints also.The welding electrodes are very expensive. Were about $60.00 per pound.If you leave them out of the box one night, all of the flux will fall off of the electrode.Very fragile.
Reply:http://www.maxal.com/files/QuickSite...g_6-11_doc.pdfsolid overview on welding Al using GTAW (and GMAW)."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:I know it is now an old thread If you see this Snowboarder88, Thank you.
Reply:Originally Posted by nmaineronI attempted to weld my transmission case with the HI FREQ box connected to my AC/DC machine.I had no problem as far as function however I had big problems with cracking after welding.I preheated the case with a propane torch a few times for cleaning and to expose any cracks.Cracks were identified and welded successfully.I had two spots where the case `was worn through.I managed to weld these spots up by building up the edges and had good solid cover.The cracks started after the the holes were filled.Initially they ran parallel with the weld but outside of the fillet.I tried to gouge the crack and fill it but after I did that, new cracks appeared and ran perpendicular and were very pronounced,so much so that I feel that there is too much to repair. i would appreciate opinions.Thanks,Ron
Reply:Originally Posted by MinnesotaDaveFlux falls off? My local store has them open on a shelf to sell just how many you want.That's how I bought them when I needed a few.
Reply:When we visited Multiplaz, I actually took some SMAW aluminum rods with me and used then to weld aluminum with their plasma welder. Left a bunch with their tech guy to play with. Sent from my SCH-I545 using TapatalkTiger Sales: AHP Distributor www.tigersalesco.comAHP200x; AHP 160ST; MM350P, Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma. For Sale: Cobra Mig 250 w/ Push-pull gun. Lincoln Wirematic 250
Reply:Nice information. Thanks to all for sharing this post.
Reply:Somebody mentioned a machine with a 30-70% EN range. I can't think 70% EN would be very versatile. I would use it with old, salvaged material. Clean material uses 75-85%. This is not true of transformer machines from 30 years ago, these machines use sine wave power, the arc virtually dies twice a cycle, leaving only the superimposed high voltage, high frequency current. Reestablishing current is easier in the EN half cycle where the electrons leap from the tip of the pencil shaped tungsten which is not oxidized. Establishing an arc from the broad surface of aluminum work piece coated with oxidation, or contamination isn't as effective. Sine wave, 60 cycle welders for the most part are 50/50 balance, but do not behave like inverter welders at 50/50 balance. Square wave welders switch polarity so quickly the ionization is still present, the EP half cycle is easily established. Comparison of balance will vary with cleanliness of aluminum. I exaggerate saying the Dynasty will weld through paint, but it is amazing!
Reply:oh man there is some good stuff on here. wish i could have found this before the semester started, ha ha. Just finished the semester learning gtaw on mild steel, stainless steel and aluminum. I didn't do so hot on the aluminum, but i was fascinated with it. I got as far as Tee, lap, and corner joints running vertical. I couldn't finish in class but I saved up enough for a used Harley and bought a Dynasty 200 DX to use at home instead My priority is to make sure I learn how to weld and hopefully use it to make enough to get the bike later. Sorry, got off track. So here's what Im doing: on 1/16 aluminum coupons around 7" long using 1/16 4043 filler, sometimes 1/16 2% lanthinated, sometimes 1/16 2% ceriated; when using the schools syncrowave 250: 1/8 pure tungsten with 1/8 4043 filler , sometimes gas lens, sometimes not. I kept the tungsten balled 1- 1 1/2 times the diameter and ran anywhere from 80 amps to 110 amps. From what i saw on the tee joint (flat and vert), the arc would move back and forth between the two plates etching a little over here, a little over there, but i couldnt keep the arc in the joint to get a puddle, and if i started too much on one side I would have trouble with etching all the way up it. Also I would stay on it so long it could get really hot. Not burn through, but just get really really hot. I'd get maybe 2 inches up before it got too hot to continue and i would have to stop. I tried to shape the arc a little with the dynasty (balance and pulsing, etc., which helped some) but soon put it back to default settings because at this point i felt like it was just cheating. It looked like, there wasn't any real penetration, so after reading this thread, Im wondering if i should've just turned the amps up some? But it seemed counter intuitive because it was already so hot. I did manage to get a couple of beads decent enough to turn in for a grade, but there was 4 restarts from getting too hot and the weld face was around 3/32 wide with no distinct ripples. I mentioned all the different tungstens but results were similar with everything i tried.My lap joint (flat and vert), using same set up, fared a lot better and I had a stack of dimes.......ish with pad plates in all positions. Is the tee joint really so different than the others, or is something not sinking in through this thick skull of mine. oh also, i never felt like the puddle was established enough to walk the cup, so it was virtually all freehand. this will be my first real post, besides intro, so if its not enough info or too much of something unnecessary then just let me know and thanks for everything so far. Last edited by Johnny Dixon; 12-18-2014 at 09:13 PM.Reason: stupid cat ran across the keyboard
Reply:You don't want balled tungsten with an inverter. Sharpen it to a point. You could easily use 3/32 or 1/8 tungsten sharpened to a point to weld those coupons. Lanthanated is a great choiceTiger Sales: AHP Distributor www.tigersalesco.comAHP200x; AHP 160ST; MM350P, Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma. For Sale: Cobra Mig 250 w/ Push-pull gun. Lincoln Wirematic 250
Reply:Originally Posted by soutthpawYou don't want balled tungsten with an inverter. Sharpen it to a point. You could easily use 3/32 or 1/8 tungsten sharpened to a point to weld those coupons. Lanthanated is a great choice |
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发表于 2021-8-31 15:01:20