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History: See history of spot welding.
Projection welding comes after success of spot time
but it's time of in use is unknown.
Definition: Projection welding varies from spot welding
in so far that the location of the weld nugget development
is not determined by the electrodes but by the location
of the projections.
Principle: Projection welding works on the same principle
of Joule E=IR2 (E= Energy, I= Current, R= Resistance)
a low volt high current is passed through projection
build up on work which heats the work that is clamped
firmly between copper electrodes, Where projection on
sheets are met to each other (R) is much more than other
contacts, Hence much heat is produced on projection
and it fuses, after a pre determined time current is
stopped then fused metal solidifies and a proper joint
build up under pressure of electrodes. |
