polarity heat

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When TIG welding the positive side produces about 70 percent of the weld heat so for more heat to the parent metal one chooses electrode negative.Does this 70/30 rule work similarly for SMAW???  Does the gas that the arc travels through have an affect on this rule?
Reply:wanna see something cool? hook the torch up positive. when i did it the tungsten fried and cracked the cup, it looked like a badly adjusted oa torch..
Reply:Yes the rule applies for SMAW also to a limited degree. The rod composition has a lot to do with how they run, but the polarity does also. Some rods run DC+ and some DC-. 6010 runs DC+ and gives deep penetration. 7014 is run DC- and has less penetration. 6013 which can be run both DC+ or DC- gives you different penetration depending on which way you set the machine.
Reply:Originally Posted by lotechmanWhen TIG welding the positive side produces about 70 percent of the weld heat so for more heat to the parent metal one chooses electrode negative.Does this 70/30 rule work similarly for SMAW???  Does the gas that the arc travels through have an affect on this rule?
Reply:After this I am really confused.  I took this 70 /30 out of the procedure handbook but I must have got it wrong.:')
Reply:YES 70% of the heat goes into the plate when using DC- TIG.Helium makes for a hotter arc than pure argon with TIG.  With Stick, More penetration is achieved with + electrode.Its apples and oranges. But its in the bible.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David RYES 70% of the heat goes into the plate when using DC- TIG.Helium makes for a hotter arc than pure argon with TIG.  With Stick, More penetration is achieved with + electrode.Its apples and oranges. But its in the bible.David
Reply:Originally Posted by Hugh Jarse   What is the official name of "the bible" you are always reading.  Where can I get a copy of it.
Reply:sorry double post
Reply:Look on www.Amazon.com for "The Procedure Handbook of Arc Welding"
Reply:$24 from lincoln plus a little shipping.  Well worth it. DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:You are lucky you were not electricuted.I would never do that with my expensive equipment.Better take you torch apart and make sure the brazed connections\are still good.You did not mention when you switched polarity if you used the selecter on the machine. or if you switched cables(worse).Polarity changes with stick welding electrodes is common.With TIG you only switch polarity on the MACHINE PANELfor a very particular reason.( Which i won't go into) AC for aluminum DC for steel and bronze.
Reply:i have a ta185 which does  not include a switch for ep/en.theonly way is to connect the cables to the +/- terminals on thje front of the machine. have used machine since without  electrical problems, will see if i cant look into the torch to check the connections.thanks for the idea.
Reply:Originally Posted by lotechmanWhen TIG welding the positive side produces about 70 percent of the weld heat so for more heat to the parent metal one chooses electrode negative.Does this 70/30 rule work similarly for SMAW???  Does the gas that the arc travels through have an affect on this rule?
Reply:Originally Posted by pulserFor SMAW (stick) welding, it is the opposite of TIG, and more heat is transfered to the base metal with DCEP. .
Reply:Well z0diac,we agree on which way electrons flow, and that their impact will heat the electrode in DCEP.  And we agree that for TIG, DCEN gives the most melting of the base metal, and with DCEP the tungsten electrode will melt at very low current.The difference between TIG and SMAW is that the TIG electrode is non-consumable, and the SMAW electrode is consumable.For SMAW,  DCEP is used with all types of  electrodes, 6010, 6011, 6013, 7014, 7024, 7018, etc. to give the most heat to the workpiece and the greatest penetration into the workpiece.  It is the same for GMAW because of the consumable electrode.  This is well documented in even the most basic welding books.How can this be, you say, because the electrons are going the wrong direction?  Again, this is because the molten droplets from the electrode very efficiently carry the heat to the workpiece by mass transport,  and the electromagnetic pinch effect is propelling the droplets at high velocity onto the base metal.It is the opposite of what you said, it is DCEN that is used for low penetration applications like 6013 on sheet metal, or even stainless steel cladding applications where low dilution of the weld metal is required.
Reply:I tip my hat to Pulser :')
Reply:A DC current can run either by having (-) charges, that is, electrons, moving in one direction or rather by having (+) particles moving the opposite direction. In a wire, only the electrons are free to move.  With a tungsten electrode in an inert gas, there are no (+) charged atoms which can contribute to the current so the electron flow constitutes all of the current, and it obeys the 70/30 rule.With a stick electrode, there is both transfer of the molten metal (as explained by pulser above) and of gases which mostly come from the coatings, both of which can provide ionized material. I believe these (+) ions, which are also speeding to the base metal at extremely high velocity, also obey a similar heat rule which may have a different ratio than 70/30. In any case, this material both brings heat and digs into the melted surface of the base metal, thereby carrying the heat even deeper. TIG has no comparable jet of material; the mass of electrons is minuscule.
Reply:Moderator: please remove post #18 and this comment too. I was editing 18 when something strange happened.
Reply:Originally Posted by Oldiron2Moderator: please remove post #18 and this comment too. I was editing 18 when something strange happened.
Reply:Originally Posted by Go1lum .......  aluminum can be welded with DC- but must be sparkly clean and helium must be used........
Reply:Argon allows the arc to be at 10 to 14 volts.  Helium wants 18+.  This is how it makes a hotter arc and deeper penetrating.You can do bigger stuff with the same 150 amps using helium or helium mix.Helium has a harder time initiating the arc.150 amps * 12 volts (argon) = 1800 watts.150 amps * 18 volts (Helium)= 2700 watts.I don't care which way electrons flow.  Just the results.David Last edited by David R; 07-08-2008 at 09:13 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Helium has a higher ionization potential than argon, 24.5 eV versus 15,8 eV, which accounts for more difficult arc starting, less arc stability at low current, and higher operating voltage for a given current and arc length.  So, it is correct, that at any given current and arc length, the helium arc is around 4 volts higher than the argon arc, and thus total available arc power, which is simply amps x volts = watts, is higher.  The higher power of the helium arc is a factor in producing more melting than an argon arc of like current and arc length, but the stronger factor is the much higher thermal conductivity of the helium plasma, 8 times higher than argon.  If you compare the volume of melting (weld size) for helium and argon TIG welds that are made at the same total power, so you adjust the argon weld current higher to get the same watts as the helium weld, you see that the helium weld is still about 10% larger.  This shows that for the same power, helium about 10% more effiecient at transfering (conducting) the arc power to the produce melting of the base metal.