Spot Welding

Last updated: May 31, 2018

What Does Spot Welding Mean?

Spot welding is a type of fusion welding that is categorized in the resistance welding family of joining processes. Spot welding involves the use of two electrodes, typically made of copper, that are clamped onto two or more materials, pressing them together. An electrical current is then sent through one electrode and the heat from the resistance of the materials between the electrodes melts them together.

Spot welding is a very popular, versatile welding process because of its ability to quickly join materials. The actual weld times for spot welding are typically measured in fractions of a second, which makes it possible to rapidly piece together large assemblies. Spot welding also lends itself well to automation and robotics.


Corrosionpedia Explains Spot Welding

Spot welding requires a relatively large amount of equipment to function properly. An electrical transformer is needed to reduce the voltage from the incoming line and increase the current. A force is required to compress the two electrodes together and clamp down the materials being welded; this is usually a pneumatic cylinder, an air/oil cylinder or a servo motor. Electrodes are also needed for spot welding to carry the current from the transformer into the part. These electrodes are available in a variety of shapes and sizes depending on the job. In applications with high run times and high amounts of electrical power, a coolant system may be needed to prevent the electrodes from overheating. A human-machine interface is also needed to adjust the settings during resistance spot welding.

Spot welding is used to join many different types of materials including carbon steel and stainless steel. Generally, as the electrical resistance of a metal decreases, the more difficult it is to join it using the spot welding process because spot welding requires electrical resistance to create the heat necessary for welding.


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