Pinch effect is the radial force or “pinch” on a conductor carrying an electrical current. For a given diameter wire, the effect is proportional to the square of the current. In gas metal arc welding (GMAW), the separation of molten drops of metal from the electrode is controlled by an electrical phenomenon called the electromagnetic pinch effect. Pinch effect on the welding wire is one of the most important factors controlling metal transfer. The shape, size and rate of transfer are governed by this phenomenon.