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Up Topic Welding Industry / General Welding Discussion / reverse polarity
- - By 52lincoln (***) Date 12-07-2008 02:19
i was wondering does it hurt one(sa 200)to reverse the polarity for awhile.lets say to run flux core wire with a suitecase.

thanks vern
Parent - By fbrieden (***) Date 12-07-2008 02:29
No.
Parent - - By welderbrent (*****) Date 12-07-2008 03:46
Not sure what the area of concern is, but no.  DC current moves through one direction.  All you are doing is switching the direction the current flows through the lines and to the work piece. 

You could picture it as the 'arc' either going through the electrode to the filler to the work piece, to the ground and back to the machine, or reverse the flow and move the opposite direction.  Very basic but I hope it makes the operation clear for you.

Have a Great Day,  Brent
Parent - - By chris2698 (****) Date 12-07-2008 04:51
I would say no because when I tig with mine I switch it
Parent - - By js55 (*****) Date 12-08-2008 13:50
'Hurt' is a general term. You will change penetration, deoxidation, and operating characterisitcs of the wire. It needs to be judged upon the type of wire in question and the application. Some wires that are specfied as reverse/straight polarity wires don't weld so well on straight. Compounds with low ionization potential need to be added to maintain arc stabilization under straight polarity since the wire is now the cathode, and some of the wires, even if they are listed as dual polarity are a little short in these compounds. You can also effect the microstructure and heat input characterisitcs for impact regimes.
Parent - - By Kix (****) Date 12-08-2008 15:38
What about the constant voltage needed to run FCAW?  Can an SA200 run CV?
Parent - By welderbrent (*****) Date 12-09-2008 01:50
I have run 5/64 Innershield with an LN-22 (I believe) on my old SAE-300, no CV.  Ran pretty well.  Could be that because of the size of the machine compared to amps and volts needed it was able to run smooth enough that it was not a problem.  Also was not doing any thing that was RT or UT. 

As far as the SA200 running CV, not that I have seen.

Have a Great Day,  Brent
Parent - By ironbanger (*) Date 12-09-2008 03:58 Edited 12-09-2008 04:00
Kix, I don`t know if you can add a wire feed module to a sa 200 that would give you cv. A friend of mine bought a multiweld 350 that you can hook up between the ln-25 and your welder that will give you Cv capability. He loves the thing and calls it his magic box . they are expensive and if you just needed Cv for a short time. I`d rent one for the job duration. You can run on cc it just runs a bit different.
Parent - By aevald (*****) Date 12-09-2008 04:28
Hello Kix and others, self-shielded wires will run fine on machines without CV capability. The real difference with regard to CV vs. VV/CC when operating machines and welding with the VV/CC is whether the process has been qualified through testing. Self-shielded wires that are run on CV are considered pre-qualified as long as they aren't required to meet seismic requirements(the T-8 wires will require qualification and adherence to manufacturer specific brands by the operator). Self-shielded wires that are run on VV/CC require qualification when they are used for any type of code-covered structural application. If I've got this wrong I'm sure there will be others out there to state this correctly for me. The self-shielded wires are certainly one of the trickiest to keep track of as far as I am concerned. Best regards, Allan
Parent - - By raftergwelding (*****) Date 12-09-2008 15:22
Hey Vern I've never run a wire feeder off my machine but have run reverse polarity all day for several days welding magnetized pipe and it didnt hurt it 1 bit i have done this on many machines and never a problem at all i know some guys that keep their machines reversed just a personnal preferance i guess but it dont hurt them to answer your question
Parent - - By hogan (****) Date 12-09-2008 15:56
Try a fillet weld break test comparing the two. The results should be obvious.
Parent - By raftergwelding (*****) Date 12-10-2008 14:57
none of the welds i ever made on reverse polarity have ever broke i have built many pipe racks our of magnetized 4 1/2in drill stem and none have ever broke no i'm not bragging just stating a fact
Parent - By tazmannusa (**) Date 12-10-2008 15:50
When welding on magnatized pipe, + or - does not make much difference on strength, - just works a lot better and faster. Like Shad mentions I have never had a problem with it eather.
Tom
Up Topic Welding Industry / General Welding Discussion / reverse polarity

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