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DESIGN TECHNOLOGY PROCESSES - METAL SPOT WELDING SPOT WELDING is one of a number of methods of RESISTANCE WELDING. The principle of Spot Welding is similar to Arc Welding in that a large electric current produces the heat source for the welding process to take place. The electrodes are made from copper to ensure good electrical contact. The weld takes place where the resistance is greatest - that is where the two pieces of metal are squeezed together between the two electrodes. The electrodes are usually water cooled. The big advantage of Spot Welding is that it is almost instantaneous and because of this the heating effect is very localised and therefore very little distortion takes place. This makes it very useful for welding thin sections of material. It is much used for the welding of car bodies and for the fixing of steel brackets onto other sections of thin sheet steel. TIG (Tungsten Inert Gas) and MIG (Metal Inert Gas) are even more efficient methods of arc welding and are much used in industry. The big advantage of MIG is that it is a continuous processes, as the metal filler rod is fed automatically and does not require frequent replacing. TIG is a more skilful process and is used on specialised welding operations. Other forms of arc welding are SEAM & PROJECTION.
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