ABSTRACT
Very often two sets of welded specimens created using exactly the same welding parameters on identical workpieces, but different welders, possess signi cantly different geometric characteristics and strength when tested. The only logical explanation to this observation is that welders make the difference. A resistance welder consists of two distinctly different, yet closely related systems: electrical and mechanical, as illustrated in Figure 8.1. The characteristics of the mechanical system, such as machine stiffness, friction, and mass, play an important role in the functionality and performance of a welding machine, and subsequently in˜uence the welding process and weld quality.
