In spot welding, the pieces to be joined are clamped between two electrodes under force, and an electrical current is sent through them. Resistance to the flow of current heats the material. Pressure is simultaneously applied to the joint, forming a solidified nugget that attaches the pieces. Spot Welding Equipment Equipment for spot welding is available in a wide range of power levels, welding forces, and hardware configurations. The most commonly used power supply systems for resistance welders are AC transformers.
Pneumatic cylinders are the most common type of forcing system.
As for hardware, spot welding systems are available in a range of configurations including pedestal, gun and hard tooling welders. Pedestal welders use standing frames to integrate the transformer and forcing systems. Gun welders are essentially portable systems for use with flexible automation. Hard tooling welders are built into other materials handling tooling. Resistance spot welding is usually accomplished through voltage control, however, the current is conventionally controlled indirectly through the applied voltage.