Function of Welding Head

Welding head holds electrode and exerts pressure on workpiece to weld.
Functions of welding head and electrode are as follows:

• 1 - To exert pressure on workpiece being welded.
• 2 - To flow welding current (a large current).
• 3 - Heat suction (To absorb heat generated in workpiece to cool).
• 4 - Forging (To press workpiece for shaping-up).
• 5 - To keep heat balance.
• 6 - Follow-up.

Various kinds of types ranging from desktop type to portable type to comply with electrode force, application, etc. Driving methods are pedal-driven and pneumatic-driven methods.

(Desktop type)

(Portable type)

Force control
Electrode force, as well as welding current and weld time, is very important factor in spot welding. Welding heat remarkably depends on contact resistance of electrode and workpiece. Improper force results in spatter and defective weld.

Follow-up
Is to exert stable pressure corresponding to expansion and shrinkage of workpiece all through the weld time. Poor follow-up results in spatter, excessive indentation. In the course of welding, thickness of workpiece varies very slightly for an instant; so the follow-up comes to be important.
Since the follow-up is inversely proportional to mass, static and dynamic frictions of movable part, reducing mass of movable part of weld head and making movable part lubricious are important to improve follow-up.