The choice of the right liner / wire guide spiral is of great importance, especially when conveying welding wires over long distances, as it is the case with the MECHAFIN Push Pull systems. For example, it is absolutely necessary to use Teflon liners for processing aluminium and stainless steel wires. With aluminium wire, higher friction can occur between the aluminium wire and the steel spiral, which then leads to increased abrasion. This can lead to clogging of the steel spiral. In the case of stainless steel wire, the abrasion of the steel spiral causes contamination in the weld joint, even if it is slight, and later rust spots.