Positive or Negative ground?

[Harry in Ky]

I do most of my stick welding with 7018. Maybe it's just my imagination, but it seems to run better for me with negative ground. Does it really make a difference?

 

[Shield Arc]

For open root pipe welding with 7018 I like DCEN, (electrode negative). But 7018 does run the best on DCEP, (electrode on the positive stud).

 

[Gary Fowler]

7018 will run on both polarities but runs better on DCEP. Electrical charges flow from the negative side to positive more easily compared to forcing it to flow from positive to negative, whereas the molten metal tends to flow to the negative terminal. Using DCEP makes it easier to strike an arc and also makes the molten metal flow toward the work piece. You notice this much more when using 6010 or 6011 rods. ON DCEN, there is noticeably more sparks coming off the rod and less penetration/less metal deposition than with DCEP. This could be the reason a 7018 runs better root passes on DCEN than DCEP, you have less metal deposition so a flatter bead which is good for root plus the arc force is higher so it keeps the excess flux blown away from the molten puddle.

 

[grsthegreat]

7018 will run on both polarities but runs better on DCEP. Electrical charges flow from the negative side to positive more easily compared to forcing it to flow from positive to negative, whereas the molten metal tends to flow to the negative terminal. Using DCEP makes it easier to strike an arc and also makes the molten metal flow toward the work piece. You notice this much more when using 6010 or 6011 rods. ON DCEN, there is noticeably more sparks coming off the rod and less penetration/less metal deposition than with DCEP. This could be the reason a 7018 runs better root passes on DCEN than DCEP, you have less metal deposition so a flatter bead which is good for root plus the arc force is higher so it keeps the excess flux blown away from the molten puddle.

thank you.. ive been wondering this myself.

 

[Shield Arc]

I'm no pipe weldor by any stretch of the imagination. But here is what the inside of a pipe looks like with 7018, and 6010 run on DCEN. Both run uphill.
First picture is 7018, second picture is 6010.

 

[buickanddeere]

Last time I checked electrons flow from the negative terminal to the positive terminal.

 

[Gary Fowler]

Last time I checked electrons flow from the negative terminal to the positive terminal.

That is exactly what I said in my post #3. Don't confuse electron flow with molten metal flow. The molten metal flows from positive to negative which is why you stick rod with positive electode but TIG with negative electrode. If you tried to TIG weld with DCEP the tungsten would melt and flow just like a stick rod, but reverse the polarity to have the tungsten negative and the arc just flows to the metal without melting the tungsten.

For a bit of useless info, a lightning bolt flows first from negative (earth) to positive (clouds with a very small electrical spark which is called a carrier then the supercharged clouds discharge the main electrical bolt back to earth from positive to negative. This is readily seen in high speed photography but not seen by the eye since it happens so quickly.

 

[Arc weld]

2/3's of the heat is on the positive side. That's why DC+ has the most penetration and 7018 runs smoother, the rod is preheated. The same reason TIG is run DC-. The tungsten would get too hot on DC+. 7018 isn't generally recommended on DC-. 7014/7024 is recommended for DC-, DC+ and AC. DC- has the highest deposition rate and lowest penetration but 7024 runs the nicest on DC-. It's good to experiment with different rods on different polarities.

 

[skyhook]

That is exactly what I said in my post #3. Don't confuse electron flow with molten metal flow. The molten metal flows from positive to negative which is why you stick rod with positive electode but TIG with negative electrode. If you tried to TIG weld with DCEP the tungsten would melt and flow just like a stick rod, but reverse the polarity to have the tungsten negative and the arc just flows to the metal without melting the tungsten.

For a bit of useless info, a lightning bolt flows first from negative (earth) to positive (clouds with a very small electrical spark which is called a carrier then the supercharged clouds discharge the main electrical bolt back to earth from positive to negative. This is readily seen in high speed photography but not seen by the eye since it happens so quickly.

Yep,:thumbsup: not too many people are aware of this,
or believe it, for that matter.