chapter  11
14 Pages

Manual metal arc welding

In the sphere of welding the electric arc has become an efficient and reliable means of welding sheet and metal plate. It is useful for welding the heaviergauge plates used for commercial vehicle body building and also for the type of metal plate processes in which the metal ranges in thickness from 3 mm to 75 mm. The use of arc welding depended naturally upon

the development of electricity, and dynamos or generators were not developed until 1880. The first actual arc welding, meaning the melting of metal by means of electrodes and thus fusing them together, was developed by Bernardoz in 1885; he created a mechanism using a carbon electrode which produced an arc between the carbon and metal, melting the edges and thus performing a weld. The arc form of welding, using the metallic electrodes, was discovered by Slavinoff in 1892, but had very little success because of the use of bare metal electrodes. However when Kjellberg, a Swedish inventor, developed the flux electrode in 1907, the success of the metallic electrode was assured. Progress accelerated as a result of the First World War, when productivity and speed of welding was of prime importance. However, it was not until the 1930s that good-quality joints could be reliably and consistently produced by the arc welding process. This was achieved by the development of coatings which gave adequate protection and improved arc stability whilst transferring metal between the electrode and the parent metal. From that time arc welding gradually displaced gas welding techniques, especially when joining heavy-gauge metal, although themajor development in arc welding was due to the production of portable and automatic welding machines. Although metal arc welding is only used a small

amount in private car construction for heavy-gauge

assemblies in cars which have chassis, it is still used in the commercial vehicle body building industry for the assembly of the fully welded, trailer-type bodies in mild steel, stainless steel and aluminium.