Effect of Polarity

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What effect does polarity have on a TIG weld.I had read that reverse polarity puts 70% of the heat into the work and 30% at the torch. While straights polarity puts 70% or the heat at the torch and 30% in the work.Does the curren have to be readjusted when switching from one to the other.Thanks Sean.MM135 on 75%-25%Miller Dialarc 250AMP AC/DC TIGSpectrum 375 Victor torchesOptrel Satelite
Reply:Im no tig welder (yet) but what you said makes since to me. Revers polarity should make deeper penetration and I would say you would have to adjust between the two.      If where lucky my bud wolfgangwelder will show up and give some advice he is the tig welder.no you cant fix it with a hot pass.BORN TO LOSE, LIVE TO WIN.
Reply:you have that backwards, and the percentages are approximate.Conventional DC TIG, such as on steel, is done DC, electrode negative, which is straight polarity. Most DC stick is run reverse polarity, electrode positive. The labels 'straight' and 'reverse' are historical artifacts from the days of bare wire welding.The heat distribution depends on the shielding gas, as well. Helium and argon have somewhat different behavior. With electrode negative, the free electrons in the arc plasma are emit from the tungsten and driven  to the material being welded. The electron carry heat from the tungsten, cooling it, to the metal, providing extra heat. In AC welding, these heavy ions impacting the material are what provide the cleaning action on the metal during the electrode positive part of the cycle. The tungsten balls due to heating from this part of the cycle when it is not being cooled by emmitting electrons, but is instead accepting them.If you need to run electrode positive in TIG, the current needs to be reduced for a given size tungsten, or the tungsten will be overheated, and may split or spit.
Reply:So then if I read you correctly. In normal use when welding steel in DC the electrode should be negative. But if you were welding on thin metal would it be better to have the electrode positive to help prevent warping by keeping most of the heat at the torch.  Thanks for the post by the way.Last edited by thenewguy4; 05-07-2004 at 10:13 PM.MM135 on 75%-25%Miller Dialarc 250AMP AC/DC TIGSpectrum 375 Victor torchesOptrel Satelite
Reply:yup. Same for stainless, copper, etc.
Reply:I weld everything but alum. on dc neg. argon coverage. Does'nt matter what thickness. If you are hot enough to fuse filler and apparent metal together you will get some type of warpage. Then it becomes a procedure process. Have not tried copper, but everything else I've welded is as I said. Yes I have welded beer cans.   revpol
Reply:Dc electrode positve *is* used, but almost never when manual welding. I have seen it used in an automated high speed machine. I agree with RevPol. DC electrode negative for copper(I have welded copper), stainless, carbon steel, etc. If it works why mess it up. It's worked for me and countless others for near half a century. Yes, I know it's been arund longer than that, but I haven't.
Reply:Welp I think I figured out my problem.See I inherited this TIG from my grandpa who died and when I got it home I hooked it up exactly the way it was hooked up at his house.It alway would melt the tungsten when you switched it to straight polarity but would work alot better when it was on reverse polarity. So I went out and tried to use it like everyone here said it should be set and it was melting the tungsten about anywhere I set the machine except extremely lot. I got to looking and the little diagram on the bottom flip up door showed that the ground and electrode wires were on the wrong posts.Thanks...MM135 on 75%-25%Miller Dialarc 250AMP AC/DC TIGSpectrum 375 Victor torchesOptrel Satelite
Reply:TNG4 watching the tungsten evaporate has always been a good indication the polarity is backasswards for me.What kind of machine is it?Appreciation Gains You Recognition-
Reply:It is a Miller Dialarc 250 AC/DC with HF.I just never thought he would have had it hooked up backwards He worked in the weld shop at American Airlines for 40 years and was a gunsmith for that long or longer. I wonder if it was done on purpose? The hose that comes from the gas solenoid goes to the ring on the stud that the torch hookes to is barrely long enough to reach, I wonder if he just swithed the leads so he wouldn't have to buy a longer hose since where the hose came out was close to the ground stud.MM135 on 75%-25%Miller Dialarc 250AMP AC/DC TIGSpectrum 375 Victor torchesOptrel Satelite
Reply:Your scenario isn't likely.If he was using the machine for welding aluminum, he might have hooked it up that way because polarity isn't a factor on AC welding.There's no rule that says you can't extend the hoses and use a piece of welding cable to lengthen the connection to the machine.If you do use an extension cable, make sure to use high quality because the HiFreq will leak out of cracks in cable insulation.Appreciation Gains You Recognition-
Reply:Ya but he welded way more ferrous metals that aluminum, he mainly worked on old Colts they didn't use much aluminum back then.I just think he had a short hose and possibly desided to hook it to the stud that was closer and compensate for it by using the polarity switch in the opposite positions. That is the only answer I can think of other than he just didn't know anybetter but I dooubt that.Last edited by thenewguy4; 05-08-2004 at 02:00 PM.MM135 on 75%-25%Miller Dialarc 250AMP AC/DC TIGSpectrum 375 Victor torchesOptrel Satelite
Reply:You don't think he just maybe used that setup to win a few free beers off dummys who never bothered to look past the polarity switch, do you?I once knew a fellow who could bulldog Black Angus Steers without breakin a sweat, and he hardly ever paid for any beer.  Of course, he did have to pay me off to keep my mouth shut about the lump sugar in his shirt pocket.Appreciation Gains You Recognition-
Reply:I doubt it. He wasn't such a cheap person as to do work for beer.MM135 on 75%-25%Miller Dialarc 250AMP AC/DC TIGSpectrum 375 Victor torchesOptrel Satelite