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Just as the title states, I'm curious if you can TIG weld aluminum without getting the white "bands" on either side of the weld bead.Is it this type of "finishing touch" that all the adjustments on a machine like the Thermal Arc 185 let you achieve?
Reply:You can try your luck reducing the cleaning a bit (EP), but it's caracteristic to Aluminium welding.
Reply:Originally Posted by turboguyJust as the title states, I'm curious if you can TIG weld aluminum without getting the white "bands" on either side of the weld bead.Is it this type of "finishing touch" that all the adjustments on a machine like the Thermal Arc 185 let you achieve?
Reply:Don't think he has the Machine yet- I assume he's trying figger if the Wave balance is a a deciding factor.http://weldingweb.com/vbb/showthread.php?t=22841Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Yes it's possibleDCEN with helium or helium/argon is one way but not really practical for thin sections. The time spent cleaning off the 'etched zone' (white bands) would just be replaced by the extra pre-cleaning necessaryNot used a TA so i don't know if you can bias the arc far enough to EN to eliminate the etched zone but it should be close. Having said that, the time spent cleaning would still be moved rather than eliminated. If the cleaning action (EP) is reduced too far weld quality will suffer (sluggish puddle with 'bits' floating about in it) unless more attention is payed to cleaning the oxide prior to weldingThe etched zone is easy to clean off anyway- if you're polishing the part that'll deal with it as will scotchbrite type finishing products if you're after a satin finish.
Reply:I have the TA-185. You can turn the AC Electrode + all the way down to 15%.DavidReal world weldin. When I grow up I want to be a tig weldor.
Reply:Originally Posted by David RI have the TA-185. You can turn the AC Electrode + all the way down to 15%.David
Reply:Originally Posted by RojodiabloYes it is possible. Try a little less cleaning. If the TA 185 works digitally like my Invertec does, try to go down to 55, then up to as much as 85 on the cleaning/ wave balance, EP, whatever we call it today. Another thing, sometimes filler rod will induce that a little bit. I have some 4043 that leaves more of a white streak than some OTHER 4043 filler. So, it is not an issue from 5356 or 4043. Much of the adjusting is done there, the frequency usually won't do too much for that issue. The other 2 options are: Paint it, or polish it!!!
Reply:Or you can clean it first and then it won't happen at all ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by zapsterOr you can clean it first and then it won't happen at all ...zap!
Reply:Yes you are right but I "guess" it's all in the Hi Freq Balance or whatever...If I clean the crap out of it at first and don't let it sit around for awhile then yes there is the "White Lines"But very very small..Compaired to if you did'nt bother to clean it off "At All"..The cleaner is better from the get go with Aluminum.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:The white lines are the effect of the AC reversal, but are also dependent on the cleanliness of the material.Since the cleaning occurs during the DCRP phase of the cycle, when the polarity reverses, it acts to push the oxide to the edge of the weld puddle. Less DCRP (maintaining your balance negative) moves the oxides closer to the puddle, since there is less cleaning time. You don't get the lines to go away, but you keep them closer to the edge of the puddle so they're not so blatant.Remember that aluminum does not change color due to heat, up to and including the melting point, so where is the white coming from? The "white stuff" in the "cleaned area" is aluminum oxide. Less aluminum oxide, less white stuff. Vigorous mechanical cleaning of the oxide (sanding, grinding, wire brushing) leaves less of it to be pushed to the edge of the weld.Or, as hotrodder said, go DCSP with 75He/25Ar, and you won't have to worry about it.I r 2 a perfessional
Reply:Kbnit:I understand everything you said and that's the way I had it in my head. But I never could have said it that 'shortly'. But I'm confused about DCRP. We're using AC for alum. Is it simply that the + and - of the AC wave = DC? Is DCRP the correct term? I should know this but......My books show EP as cleaning and EN as penetration with AC. And then there's DCEP = DCRP? and DCEN = DCSP? for stick welding. Ok, I'm confused.TIA, Craig Oops, my contribution to the thread is: I don't think aggressive cleaning fits the criteria. The whole point is a pretty piece (intercooler?).9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:Aluminum can be tig welded with with Direct Current Electrode Negative. The piece has to be cleaned SPOTLESS just before welding and even kept in gas coverage before welding so it doesn't form oxides by the time the weldor gets to it. The helium and argon make for a hotter arc. This is why its not for thin stuff. This had no cleaning ability at all, but will make nice welds. No I have never done it but there are some examples in this forum.Also Mig welding aluminum is done Direct Current Electrode Positive. It works quite well with pure argon shielding gas. I have done this. Cleaning is great. Short circuit can be done, but most is spray or pulsed spray.When using wave balance, if you have 25% electrode +, then you get 75% electrode - so this makes for more heat in the work than if you had just 50%+ and 50% - like with a transformer machine. I have not got satisfactory welds with less than 20 to 25% Electrode +.With 55% to 60% electrode +, I have balled an 1/8" tungsten using 100 amps.David Last edited by David R; 07-26-2008 at 07:02 AM.Real world weldin. When I grow up I want to be a tig weldor.
Reply:Originally Posted by Donald BranscomOR...get the weldment anodized any color you want.
Reply:Originally Posted by David RWhen using wave balance, if you have 25% electrode +, then you get 75% electrode - so this makes for more heat in the work than if you had just 50%+ and 50% - like with a transformer machine.
Reply:Originally Posted by David RAluminum can be tig welded with with Direct Current Electrode Negative. The piece has to be cleaned SPOTLESS just before welding and even kept in gas coverage before welding so it doesn't form oxides by the time the weldor gets to it. The helium and argon make for a hotter arc. This is why its not for thin stuff. This had no cleaning ability at all, but will make nice welds. No I have never done it but there are some examples in this forum.
Reply:Transformer based machines have adjustable balance (typically max of 68%EN) but not as adjustable as a true inverter. Inverters also let you adjust the AC frequency (higher frequencies = tighter arc cone + slightly deeper pen)Bottom line, while inverters typically leave a slightly narrower etched zone there's no shortcuts to completely eliminate the etched zone- either more time preping the part for welding or time spent polishing it off afterwoods is gonna be needed
Reply:Craig,sorry for the confusion. I should have used the newer, more accepted terms, but old dogs and all that.DCSP (Direct Current Straight Polarity) is the same as DCENDCRP (Direct Current Reverse Polarity) is the same as DCEPI r 2 a perfessional
Reply:Originally Posted by kbnitCraig,sorry for the confusion. I should have used the newer, more accepted terms, but old dogs and all that.DCSP (Direct Current Straight Polarity) is the same as DCENDCRP (Direct Current Reverse Polarity) is the same as DCEP
Reply:Clean it good, that makes the biggest difference, the gas mix can also make a big difference.Me!
Reply:Originally Posted by Me!Clean it good, that makes the biggest difference, the gas mix can also make a big difference.
Reply:Craig,Now I understand your confusion. We were talking about how to minimize the AC signature on aluminum. Recall that I said: "Or, as hotrodder said, go DCSP with 75He/25Ar, and you won't have to worry about it." DCSP and DCRP are DC processes, not AC, and DCSP would be used in lieu of AC in order to remove the AC signature from the edges of the weld. No arc cleaning with DC, so no signature from the arc clean. I was referring to an alternate to AC, not a derivative of AC.And no, I don't think you're trying to re-write any manuals I r 2 a perfessional
Reply:Kbnit:THANK YOU for the follow-up. I missed the Or go DCSP. We have a 'meeting of the minds'. And I understand even better, because there is NO cleaning with DCSP; therefore no oxide cleaning zone. I get discouraged when I p!ss someone off before I get the question across. 9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:You can DC weld aluminum ?Yes, you canI r 2 a perfessional
Reply:Originally Posted by turboguyYou can DC weld aluminum ?
Reply:Originally Posted by kbnitYes, you can
Reply:There's a reason AC is the most widely used method...DCEN with a helium or helium/argon mix is a hotter process- useful for thick sections, makes life more difficult with thin material.As with AC, weld appearance is down to operator skill but it's more difficult- poorly defined weld pool, higher travel speedsHelium is more expensive and (as it's lighter than air) more flow is required, i.e. you'll get through gas more quickly too.It won't save you any time. As i've already said you'll spend at least as much time prepping the part for welding (oxide removal) as would be required to polish off the etched zone afterwoods
Reply:I've done quite a bit of DCEN TIG on heavy aluminum with helium, and just tried it with argon on thin sheet just recently, here is the link.http://weldingweb.com/vbb/showthread.php...=dcen+aluminumFrom what I experienced, it looks like DCEN of aluminum with argon works pretty well.
Reply:Turbo,Really, the only difference in welding DCSP on aluminum is the shielding gas, I use 75%He/25%Ar. Stainless wire brush your faying edges, and then wipe down with the solvent of your choice to remove the oxide dust that the brushing produces. Clean till your wipe has no black residue on it. Then DC weld as you would with any metal, except, as has been noted above, you WILL need to get your move on. Welding slowly allows excessive heat to shunt away from the weld into the base metal, and your puddle will continue to get wider as you go. Till the whole thing sluffs off on the table.Yes, AC is definitely and will continue to be the most widely used method, but with the newer inverter technologies, more and more people are finding DCSP on aluminum isn't the "black art" that it was once thought to be. Some considerations for me for DC welding aluminum. Flight hardware. The weldments cannot be "finished" after welding. That means no heavy wire brushing, scotchbrite, sandpaper, grinding, etc. And the weldments have to be penetrant inspected. All that "arc-cleaning" from AC leaves thousands of little pits adjacent to the weld. And every one of those thousands of pits holds penetrant. Inspector won't even waste his time, just reject the whole lot. With DC, smooth weld out of the booth, no problems with penetrant.High Vacuum applications. Again, all that arc-pitting adjacent to the weld increases the surface area of the weldment by hundreds or thousands of times, also increasing the amount of time needed to evacuate semiconductor processing, vacuum processing, and scientific equipment. And lastly, just aesthetically pleasing. With no "white lines, going through my mind..." Sorry, got carried away there, there's almost no post-weld finishing required, except a little brushing, and you're good to go.No one process is best for every application, but having every process in your toolbox is invaluable. Give it a shot, then, if you ever need it, you'll have it there.I r 2 a perfessional
Reply:I have a few nice cupons, probably 1/4" thick, I will give it a shot.David Real world weldin. When I grow up I want to be a tig weldor.
Reply:So - extra prep time for DC aluminum vs extra finishing time for AC aluminum with the total being similar -- is that what I'm reading?On some of the aluminum items I will be welding, polishing likely won't be an option given the overall size of the workpiece, and the fact you can't just polish the white area and have it "look right". So, using DC could have some real benefits for me.Given the extra heat we're talking about with the DC-process on aluminum, would there be a limit on how thin you could go using a decent inverter machine? I really can't see having to work on anything thinner than 0.040 sheet at my end.If I could run pure Argon it would allow me to use just one bottle for Steel, S/S, and Aluminum. I could also use it for tacking with the MIG when fitting.Fewer bottles is a good thing when space is limited
Reply:Turbo,Depending on what inverter type machine you've got, the manufacturer may even recommend that you go ahead and use pure argon with DCSP on aluminum. I know on the Miller Dynasty 300DX, they recommend pure Ar. That'll cut down on your bottles.I r 2 a perfessional
Reply:Turboguy,Note: i'm just being blunt, not rude...From your recent posts you're new to welding. I'm guessing a virgin when it comes to the TIG process, at leastIf you intend to work with aluminium get an AC/DC machine! Talking about welding 0.040" aluminium DCEN is one thing, actually doing it with little to no experience is quite another!
Reply:Turboguy: FWIW: I'm a self taught hobby guy.I'm with Hotrodder on this, you're headed the wrong direction. Guessing by your 'Turboguy' name, you're going to be welding intercoolers, etc. The rest of my post is based on that assumtion.Kbnit and Pulser don't work at the corner weld shop. I think their background is in the aerospace and nuclear aspect of welding. Their education in welding is engineering degrees. And I think that they're talking hypothetically. Can DC be used for alum welding? Yes, it can. But its usefullness is for thicker alum. Certainly 1/4" and up. I don't believe either would use DC on the alum you're talking about.I believe that you should re-read Hotrodder's posts. He is answering your questions. Look at David R's results in the other thread on DC alum. That's what it's really going to look like. And David's pieces were laying on a steel table, supporting the alum. If you try that on a fitting to an intercooler, you'll have nothing but a 1" diameter hole.Learning to weld .040 alum is HARD. Don't complicate it. AC is necessary.Reality check complete.Craig Last edited by Craig in Denver; 08-01-2008 at 05:22 PM.9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:Turboguy, I agree with Craig in Denver.You're asking an awful lot if you're going to try and burn DC on any aluminum thinner than 3/16" thick. I can weld .065 alum. tubing pretty well with AC, but even with all the control in the footpedal and the adjustability of an inverter welder, I still get my issues from time to time. I would have to use the word "IMPOSSIBLE" for a DC weld on that thin of material.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Thanks guys I appreciate everyone's input and advice here And AC/DC machine it is, then.
Reply:Bumping because I am also interested in reducing these white lines. Will those plastic brush wheels that go on bench grinders take it off without changing the surface finish? There was some stainless cleaning solution at the local welding store that I tried out. It smelled like cichoric acid. You would spray it on the weld, let it sit for 15 minutes, then wash off. It would take off all the coloring from welding and just leave a nice clean stainless look to the material and weld. Is there something similar for aluminum?I'm gonna try out a smaller cup with less of the electrode sticking out and see how much that helps. I welded this up last night, those white lines piss me off.
Reply:Originally Posted by Craig in DenverKbnit: I don't mind talking 'old dog', I am one. I understand EN and EP. But when the terms DCEN and DCEP are used in an AC process, I get lost. I think it should be ACEN, and ACEP. No, I'm not trying to rewrite the manuals, just trying to phrase my question.On my Syncro output selector switch there are 3 positions: AC, DCRP and DCSP. So DCRP can't be used when welding AC alum?I'm not trying to 'tech talk' this to death. I know where to set it to weld.
Reply:Reverse current etching is inherent to the AC process. As mentioned above, if you are working on critical parts that have post weld penetrant inspection, you can't mechanically remove the white lines. Any mechanical disturbance to the finished weld must be acid etched before penetrant application and interpretation.For hobby welders and non critical parts? Brush away. Scotch brite pads on a highspeed sander work well too.You can DCEN .125 material pretty easy and maybe even thinner if you have the hand for it. The cleaning isn't all that critical either for hobby welds. Just brush or scrape the weld areas and blow the dust off with clean air. Weld it just like steel. You need ultra pure helium to do it right and it aint cheap.Two turn tables and a microphone.
Reply:With some newer machines, like the Dynasty 350DX, there is also a setting that allows the user to set the amperage for the (+) cleaning function independently from the (-) phase of the cycle. That allows the user to get a smaller cleaning action "band" -- just enough for cleaning, and no more. That keeps heat out of the part as well...
Reply:Originally Posted by Mr. MooseWith some newer machines, like the Dynasty 350DX, there is also a setting that allows the user to set the amperage for the (+) cleaning function independently from the (-) phase of the cycle. That allows the user to get a smaller cleaning action "band" -- just enough for cleaning, and no more. That keeps heat out of the part as well...
Reply:Also looks like the dynasty line is the only one with adjustable AC EN. Plus the wireless foot control looks nice. I hate that wire! Battery(s) last with those?
Reply:I have been experimenting with the dynasty 200. I have been able to get to about90% to 95% EN before getting dirty puddle if th aluminum is new and pretty to start out. At 90% the puddle is a little less fluid when dipping the rod. 85% is a little better.I have done welds where the lines couldn't be seen much or at all - but I don't knowwhat I did different. Have you tried a light glass beading after welding ?That would kill the gloss on the sheet though ........ if you want gloss..There are some man made plastic blasting media which might be used to re-polishthe glass beaded weld area.... but you will have to check the grit sizes and researchwhat applications it works well for. I think there is a publication in the library just formetal fnishing tecniques. Might look there !Tim
Reply:Yeah I like the factory finish on the aluminum and put allot of effort into saving it but then get the white lines. I tried to stay real close with the tungsten on this intake to cut down on the lines and I do think it helped some. I am still going to try out pulling the tungsten back into the cup farther to see if that helps as well.I have a blast cabinet and do glass bead lots of stuff with it but it dulls aluminum. Possibly some kind of plastic beads or nut shells would work out. Some of that media is kinda pricey though, I think thats why I have held off on getting random stuff to just try out.Besides my smudgy finger prints all over the intake you can see I kept the finish nice and thats not easy when cutting it, mocking it up, and welding, then more mocking up and drilling, etc. Its allot of working with a part to not scratch it.
Reply:The only way you're going to be able to eliminate the cleaning band is by doing a passivization after welding, like you would before anodizing. This restores all of the oxides to a uniform depth, making the surface appear new.Moving the tungsten around, playing with gas flow, torch angle ect is just a waste of time. As long as you are using AC, it will be there.Have we all gone mad?
Reply:From what I read that is mostly for stainless steel. Any more info?
Reply:Subject has been beat to death, but I'll throw in my .02 worth.The "white lines" adjacent to an AC weld bead on aluminum are what is referred to the "etch zone". It's where the DC+ is bombarding the aluminum, breaking up the oxides so that welding occurs on clean metal.Increasing your balance control (on miller machines) increases the time the machine spends in the DC- mode (more penetration/less cleaning). This, by the nature of the wave, reduces the etch zone.The newer inverters will reach a higher level of DC- than was possible with the transformer based machines. With proper fine tuning of the balance control (on the inverters), you should be able to virtually eliminate the etch zone adjacent to the weld bead. As you approach the maximum DC- (99% on a Dynasty 200) you're virtually welding in DC even though you have the machine set on AC.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:Thank you, I understand all that, I was asking about more info on the passivization. |
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发表于 2021-8-31 23:27:55