Which metal transfer method is characterized by one droplet forming on the electrode at a time?

The pulse arc transfer method is characterized by one droplet forming on the electrode at a time due to its unique operation in a controlled pulsing environment. This method uses short bursts of high current to create a molten droplet at the tip of the electrode. The pulsing effect allows for precise control over the droplet formation and transfer, which enhances penetration and reduces the heat input into the workpiece. This careful control makes it especially useful for thin materials or for applications requiring a clean finish.

In contrast, the other methods involve different transfer dynamics. Short circuit transfer involves continuous contact between the electrode and the workpiece, leading to a different droplet formation and transfer mechanism. Spray transfer involves a steady transfer of multiple droplets at a high rate, often requiring higher currents and providing a different quality of weld. Submerged arc transfer operates under a layer of flux that masks the weld area, producing a different welding profile altogether and not focusing on single droplet transfer.

Thus, the pulse arc transfer method stands out because it emphasizes the individual droplet creation and transfer process, making it distinct among the various metal transfer methods in GMAW.