Junkers' Experiments in Spot Welding

IN metal aeroplane construction the advantages of spot welding compared with riveting are very marked: production costs are reduced, components are lighter, and the skin can bo made smoother. In the production of aeroplanes of the Junkers Works at Dessau these advantages were recognized at an early date; as long ago as 1915, electrical contact resistance welding was used to a large extent in one of the earliest types, the steel J.2. In the subsequent change over from steel to light alloys, electrical contact resistance welding could not be continued; obstacles were presented by the good electrical conductivity of light alloys and their great sensitivity to the effects of short exposure to high temperature, also by their strong tendency to stick to the copper electrodes.