Simply defined, spot welding is "the welding of overlapping pieces of metal at small points by application of pressure and electric current."
Spot Welding occurs in three stages:
- Electrodes seated in a weld head are brought to the surface of the parts to be joined and force (pressure) is applied
- Current is applied through the electrodes to the workpiece to melt the material
- Current is removed but electrodes remain in place at force to allow the material to cool and solidify
Weld times range from 0.01 sec to 0.63 sec depending on the thickness of the metal, the electrode force and the diameter of the electrodes themselves.
Basic equipment used in the spot welding process consists of a desktop workstation including a welding power supply, a weld head and electrodes. More sophisticated manufacturing may use automation and/or robotics.
See resistance spot welding for more information.
The term "spot welding" is also used in the laser welding process to describe the spot welds generated by single pulses of laser light. See laser spot welding for more information.
And for more information about the resistance welding process read our Fundamentals of Resistance Welding, Large Scale Spot Welding Applicatons and Fine Spot Resistance Welding Applications articles.