Irene,

copper free welding wires have - as far as I know - originally been investigated and developed by japanese manufacturers, see also

http://www.kobelco.co.jp/english/environment/2005/1174642_2856.html.

Practically with the same time ESAB has launched a copper free welding wire, see also

http://www.engineeringtalk.com/news/exv/exv114.html

I was attendee of the 2004 annual IIW-Assembly been held in Osaka Japan, where I have also participated to the common large international welding conference which is focussed on all experts coming from the different IIW-Commissions and Sub-Commissions. I can remember a Japanese colleague who has held a lecture concerning non coppered solid wire-electrodes for Gas Shielded Metal Arc Welding. Also a larger delegation coming from ESAB was there and it was interesting to see and particularly listen to the afterwards discussion...

Well, I was interested in this topic and have tried to find out if the non coppered surface of the wire would really have such great benefits for the welder, as described by the Japanese colleague. But after my return from Japan I was unable for finding any welding-application under utilization of non coppered electrodes out of the borders of Japan. Until I have read the »Paton Welding Journal Edition 4/2005«. Here the author A.N. Kot, has reported of »New Developments of Concern ESAB - OK Aristo Rod and Marathon Pac for MAG Welding«. This article is dealing in depth with exactly these new non coppered wire-electrodes for GMA-Welding. He wrote of three different wire quality levels comparing with the subsequent AWS-standards:

-  ER70S-6
-  ER70S-3
-  ER70S-6 with higher mechanical properties under CO2

What the investigations results of the wire properties, comparing to coppered solid wire-electrodes, were, can be concluded as following:

-  Lower wear of the contact tips
-  Increased Arc Stability
-  Advanced Uniformity of wire feed through the hose package, and thus...
-  Ability to feed the wire over longer distances (through longer hose packages)
-  No more metal dust pollution (copper abrasion) of feeder rolls and wire inner liner  
-  Decreased quantity of fumes within the welders working zone
-  Improved corrosion resistance through special coating (ASC = Advanced Surface Characteristics) increases the storage periods

As the author writes, all these advantages lead to "Increased Welding Efficiency". Furthermore of three interesting industrial applications has been reported which I would like to list subsequently:

1.  »VBG Warneborg« company (Sweden) is using this new wire-electrode for welding automobiles with load carrying capacity of more than 16 tons. They have - as reported - increased their efficiency for app. 15% comparing with coppered solid wire-electrodes.
2.  »Fai Komatsu Industries« company in Padua (Italy) has not only "essentially" increased welding efficiency but also met the requirements of ISO 14.000-standard which is regulating the environmental effects in welding, by using the non coppered wire.
3.  One of the worlds largest ship-yards »Kvaerner Masa Yards« was allowed to using hose packages of 37 m length without using additional intermediate wire feeding units, for both side simultaneously welding of beams, 22 m long. These beams are welded under using two welding heads on each side - being fed with three wires. This is, 12 wires are simultaneously being fed and thus are involved into the welding-process! The beam elements are welded for one pass at high speed by continuous or discontinuous fillet weld with 2.4 to 8.0 mm leg. Here they are using non coppered wires with diameters of 1.6 mm and 2.0 mm with a great increase of efficiency and process-stability.

As far as I interpret the report from the Paton Institute Ukraine, the new wires have some specific benefits to be marked. Although nothing is reported about the used parameters while the investigation, some very interesting data about feeding forces and quantities of copper shares in welding fumes are explained and stated within the mentioned report. Furthermore I do not mean that the differences in welding-parameters to be used between non copper surfaced wires and coppered wires may really be significant. I don't know if these information may help you but nevertheless my best regards,
Stephan