Resistance Spot welding: Spot welding is employed to join overlapping strips, sheets or plates of metal at small areas .The pieces are assembled between two electrodes, which must possess high electrical & thermal conductivity and retain the required strength at high temperatures, so they are made of pure copper for a limited amount of service, and of alloys of copper or tungsten, or copper and chromium for continuous working. When current is turned on, the pieces are heated at their contacts to a welding temperature, and with the aid of mechanical pressure the electrodes are forced against the metal to be welded.
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Advantages of Resistance Spot Welding
1. Comparatively Low cost
2. Resistance Spot Welding (RSW) method doesn't need highly skilled worker.
3. Distortion or warping of parts is eliminated though it leaves some depressions or indentation.
4. The joint made is highly uniform.
5. Automatic or semi-automatic operation both can be done.
6. There is no need for edge preparation.
7. Welding can be done in quick succession. It just needs a few seconds to make the joint.
Disadvantages of RSW –
1. The equipment cost is high so it can has an effect on the initial cost.
2. Skilled welders or technicians are needed for the maintenance and controlling.
3. Some metals need special surface preparation for making the RSW a success.
4. The thick jobs are not easy to weld.