Process and Equipments involved in Spot Welding:
Spot welding is otherwise known as Resistance welding (RSW). In spot welding, there is some amount of heat generated when there is resistance to electric current flow. This heat is in-turn used to weld the contacting metal surfaces. The parts that are joined by this process are of 3mm thickness and the diameter varies from 3mm to 12.5mm. The amplitude, the duration of current passed and the resistance between the electrodes determines the amount of heat distributed to the spot to be welded. In short, the spot welding process involves three stages. In the first stage the electrodes are brought closer to the surface of the metal, a slight amount of pressure is applied to do so. This is immediately followed by the application of the current from the electrodes for a brief span of time after which the current is removed, but the electrodes remain in place allowing the material to cool. The thickness and the diameter of the material determines the weld time which normally range from 0.01sec to 0.63 sec.
The two main equipments used in the spot welding process are the tool holders and the electrodes. The electrodes are generally made of low resistance alloys, usually copper and the tool holders are used to hold the electrodes in place and also support the water hoses which are used for cooling. Not to forget about the materials that are being welded, which are the workpieces and they should conduct electricity. The coolant used in the spot welding mechanism could be both water and brine solution. By using all the mentioned equipments and by accurately following the process, we can obtain perfectly spot welded end products.