The use of variable polarity current for gas metal arc welding (GMAW) has been investigated experimentally. The main objective was to study the effects of percentage of DCEN versus DCEP current on bead characteristics and arc stability. Experimental bead-on-plate tests were performed on mild steel plate using 0.045 inch diameter ER70S-6 wire. The percentage of DCEN current versus DCEP current was found to have significant affects on penetration, power, and arc stability. Penetration and welding power were found to be reduced with higher percentages of DCEN current while arc stability problems were increased with higher percentages of DCEN. Shielding gas tests revealed that argon gas with a minimum content of 5% oxygen or carbon dioxide provided the most stable transfer when using DCEN current. High speed video was used to study arc stability and transfer characteristics of the variable polarity process. Experiments revealed that drop size increases with increasing percentages of DCEN current. Switching frequency was also found to have a small effect on drop size, but had a major effect on arc stability. Arc stability appeared to be best when switching frequency was equal to the frequency of droplet transfer.

Here's the link to the .pdf:

http://search.ohiolink.edu/etd/send-pdf.cgi/Talkington%20John%20Eric.pdf?osu1130352747

Enjoy the reading... I know I did!!! :) :) :)

Respectfully,
Henry