Type ER70S-6 welding wire is offered with and without a copper coating. The welding characteristics of this often used welding wire, especially the process instabilities and the causes thereof when MSG welding, have been thoroughly investigated and the complexity of the topic has been explained in numerous publications. In practice, the conveying properties of the wire electrode are repeatedly blamed for the process instabilities. Steps taken by manufacturers to improve the surface finish and thus improve the welding energy flow to the contact tip in the case of poor welding wire flow, often had little to no effect.
In order to reduce friction, many welding wire manufacturers revert to coating the wire surface. What effect the wire coating has on the welding characteristic has been the subject of many a manufacturers internal study. Just how the coating alone effects the welding process is difficult to assess with any certainty.
In order to present the effects of deep cleaning a wire using a wet/chemical system that cleans the very pores of the wire surface, GEO undertook cleaning and coating tests. Coated and uncoated wire from several manufacturers was used. The characteristics were then compared and documented following tests on a GEO designed weld testing unit Type (WWTE). The results are presented in the article "Surface treatment of welding wires ER70S6 and their effect on welding properties". You can download the full article below.