{"id":17782,"date":"2022-05-23T18:15:56","date_gmt":"2022-05-23T15:15:56","guid":{"rendered":"https:\/\/fractory.com\/?p=17782"},"modified":"2024-08-12T14:06:08","modified_gmt":"2024-08-12T11:06:08","slug":"spot-welding-explained","status":"publish","type":"post","link":"https:\/\/fractory.com\/spot-welding-explained\/","title":{"rendered":"Spot Welding Explained"},"content":{"rendered":"
Spot welding is a resistance welding process<\/a> that joins metals together by applying pressure while supplying electric current to the weld area. It was first introduced in 1885 when Elihu Thomson accidentally fused two copper wires together in an experiment.<\/p>\n Spot welding has become a staple welding process in manufacturing and assembly, especially in the sheet metal fabrication<\/a> sector and automotive industry. Suitability for automation plays a big part in its rise in popularity as robotic spot welding excels at speed and efficiency.<\/p>\n Let’s delve deeper and further understand what resistance spot welding beholds.<\/p>\n Spot welding (RSW) is an electrical resistance welding process that joins overlapping metals between two electrodes. Pressure is applied by squeezing the workpieces between the electrodes and heat is generated by the passage of welding current through the resistive metals. This allows the materials to fuse and create a welding joint<\/a>. The joint created through resistance spot welding resembles a button or a nugget, thus the term spot welding was coined as the current is applied precisely over a small area on the metal’s surface.<\/p>\n As the metals are fused using large amounts of energy in a short period (approximately 10-100 milliseconds), the area around the weld nugget stays unharmed by the excessive heat, thus the heat-affected zone<\/a> is minimal and a clean weld is created.<\/p>\n The amount of heat generated in spot welding is expressed by the heat-energy formula:<\/p>\n Q = I2Rt<\/strong><\/p>\n Where Q is the heat energy, I is the current, R represents the electrical resistance and t is the time or duration in which the current is applied.<\/p>\n The spot welding process works through the delivery of low-voltage, high-current electrical pulses to the weld electrodes in order to almost instantaneously melt the metal while applying enough pressure for the metals to fuse. The process resembles the cold welding process<\/a> in terms of applying pressure, but in cold welding, no electrical current is supplied to the weld.<\/p>\n The first stage in spot welding is to place the overlapping metal sheets or workpieces. After the metals are firmly set in place, the application of pressure through the electrode force is performed. This pressure may be applied manually, pneumatically, by springs or through hydraulics, depending on the machine type.<\/p>\n The second stage involves the application of heavy current to the targeted area between the electrodes. Molten metal forms as the current reacts with the metal’s internal resistance. The metals reach about 2000 \u00b0C, which is above their fusion point. The electrodes must have a higher melting point than the workpieces. Generally, copper alloy electrodes are used but depending on the welded metal, the electrodes can also be made from tungsten, molybdenum and other materials.<\/p>\n The final stage involves the cooling and solidification of the nugget. In this stage, the welding electrodes remain in contact with the nugget and act as support as the metals cool down and harden. The process is finished once the metals have cooled down.<\/p>\n\n
What Is Resistance Spot Welding<\/h2>\n
Spot Welding Process<\/h2>\n