DESIGN TECHNOLOGY - Download as DOC by HC121107073246


									                 DESIGN TECHNOLOGY
                  PROCESSES - METAL
                    SPOT WELDING
SPOT WELDING is one of a number of methods of RESISTANCE

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
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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