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Mith
05-30-2007, 04:16 AM
I read somewhere about using reverse polarity for stainless (DC arc). Using the electrode as - and ground as +.

I'm only welding 2mm sheet, and even so it wasn't melting well with quite a few amps, just wouldn't heat up well, it was reasonable cool to touch only a few moments after welding.

I'm welding a hydraulic tank, so I want it to be leak proof, so lots of penetration.

Any mileage on welding with reverse polarity for stainless?

Jeff
05-30-2007, 07:41 AM
Reverse polarity is Electrode positive.
Straight polarity is Electrode negative.

clive
05-30-2007, 07:54 AM
I would go the opposite way to Jeff. I teach reverse polarity is the hand piece is negative. I'm talking stick welding. Some welding machines work better on that. At our tech. our machines of one brand all run better on reverse polarity except for one rod which we have to run positive. Our other machines are the opposite. What essentially happens is on negative the majority of the heat is in the work so if the work and rod were same dimensions the work would be consumed. On positive the rod would be consumed. As the job is bigger it is a better heat sink so the rod of course melts but you will find they really heat up when you are getting down to a stub. Hope that clarifies it.

Shade Tree Welder
05-30-2007, 08:55 AM
Reverse polarity is Electrode positive.
Straight polarity is Electrode negative.I will confirm that Jeff is right.

Reverse polarity
Electrode
Positive

REPresentative

Straight polarity
Electode
Negative

SENator

See the politicians really do have their hands in everything....:eek::rolleyes:

Typically most stick (SMAW) welding is done with the electrode positive or reverse polarity.

Mith
05-30-2007, 08:57 AM
Either way, do I want the electrode negative for stainless?

Thanks

Shade Tree Welder
05-30-2007, 08:59 AM
Either way, do I want the electrode negative for stainless?

ThanksNope.

Mith
05-30-2007, 09:02 AM
Ok, thanks:)

Jeff
05-30-2007, 09:15 AM
I would go the opposite way to Jeff. I teach reverse polarity is the hand piece is negative.

It would be good if you taught the correct terminolgy.
This is from Lincoln Electric;
Polarity results from the fact that an electrical circuit has a negative and a positive pole. Direct current (DC) flows in one direction, resulting in a constant polarity. Alternating current (AC) flows half the time in one direction and half the time in the other, changing its polarity 120 times per second with 60-hertz current.

A welder should know the meaning of polarity, and recognize what effect it has on the welding process. It is the ability to adjust polarity that lends DC welding kits versatility. With few exceptions, electrode-positive (reversed polarity) results in deeper penetration. Electrode-negative (straight polarity) results in faster melt-off of the electrode and, therefore, faster deposition rate. The effect of different chemicals in the covering may change this condition. The high cellulose covered mild-steel rod, such as Fleetweld 5P or Fleetweld 5P+, is recommended for use on positive polarity for general welding. Some types of shielded electrodes function on either polarity, though some operate on only one polarity.

Jeff
05-30-2007, 09:29 AM
And, Stainless should be run DCEP "reverse polarity"

calweld
05-30-2007, 09:44 AM
And the machines themselves should make no difference . . If I had two machines that each seemed to run the same rod better on opposite polarities, I'd be using a DC voltmeter to confirm the actual positive and negatives corresponded with the labels on the face of the welder.

Mikey
05-30-2007, 10:56 AM
DC current always runs negative electrons (too many) towards positive (not enough).

Like in most cars, nowadays, you have a negative ground. Which means the current runs through the chassis towards the headlight, power window, whatever.

I know it sound "backward" but think of it like this: The negative terminal has an over abundance of "negative" charged electrons which desires greatly to reach equlibrium and races like heck towards the positive post to do so.

So, that's why when you say "Electrode Negative" it means current flows STRAIGHT from the rod to the ground. Most Stick Arc is done reverse however, with the current flowing from the ground to the rod, REVERSE current. (electrode is positive).

For stainless steel, you gotta run DC REVERSE (most normal), and try E-308-15 or E-310-15

flange jockey
05-30-2007, 01:06 PM
mith if you try both polarities the difference should become obvious,electrode pos,always gives a smother weld with a lot less spatter.it seems to sound right also.there may be some exceptions this is just my experience with s/s electrodes.

Hobweld
05-30-2007, 03:39 PM
I was taught like this.

Reverse Polarity = Rod Positive
RP=RP

Done deal.
Ken:D

D York
05-31-2007, 08:21 AM
What about polarity in Tig welding for mild steel & stainless?

Mikey
05-31-2007, 12:37 PM
What about polarity in Tig welding for mild steel & stainless?

Use straight polarity as this puts the heat on the work, and not on your electrode. (electrode negative). For aluminum and magnesium, use AC.

OZWELDER
05-31-2007, 03:37 PM
Mikey has just about answered the question why you should want to run electrode positive on a ( stick ) electrode.

Some metals ,including stainless steel react adversely from the excess heat input of the (stick ) electrode set on Electrode Negative.
On the this polarity, approximately 2/3rd of the heat is in the metal and 1/3rd heating the stick. Because stainless is a good conductor,distortion from excess heat is one of the unwanted welding consequences.

Low hydrogen electrodes are one more application example and yet another is the electrode types used for cast iron.

Tig naturally, is different because the heat input is way lower

Have a great week end!
Ozwelder

mccutter
05-31-2007, 10:16 PM
I would go the opposite way to Jeff. I teach reverse polarity is the hand piece is negative.

I guess they do things "backwards" down under... ;):D

clive
06-02-2007, 08:07 AM
I guess they do things "backwards" down under... ;):D

It would seem so, I based this on the fact that the hand piece is in the connector marked- and the earth in the connector marked +
I stand corrected.
Clive

Lu47Dan
06-07-2007, 01:42 PM
Electrode negative in tiq welding makes your tungsten last a lot longer also , just try it Electrode positive and see what I mean . Psst , grind grind grind :eek: Dan