Changes

During vertical wire welding the contact material is vertically fed in wire formthrough a clamp which at the same time acts as one of the weld electrodes''(Fig. 3.9)''.  [[File:Vertical wire welding (schematic).jpg|right|thumb|Vertical wire welding (schematic)]] With one or more weld pulses the roof shaped wire end – from theprevious cut-off operation – is welded to the base material strip while exertingpressure by the clamp-electrode. Under optimum weld conditions the weldedarea can reach up to 120% of the original cross-sectional area of the contactwire. After welding the wire is cut off by wedge shaped knives forming again aroof shaped weld projection. The welded wire segment is subsequently formedinto the desired contact shape by stamping or orbital forming. This weldingprocess can easily be integrated into automated production lines. The contactmaterial must however be directly weldable, meaning that it cannot containgraphite or metal oxides.