How many types of metal transfer are commonly identified in MIG welding?

In MIG welding, four types of metal transfer are commonly identified: short-circuiting transfer, globular transfer, spray transfer, and pulsed spray transfer. Each type of transfer represents a different method of how the molten metal from the electrode moves to the workpiece, impacting the welding process's characteristics, such as the heat input, penetration, and bead appearance.

Short-circuiting transfer occurs at lower currents and voltages, where the electrode wire contacts the weld pool, creating a short circuit that allows for a continuous transfer of metal. This method is ideal for welding thin materials as it provides better control and minimizes distortion.

Globular transfer happens at higher current levels and is characterized by larger droplets of molten metal being transferred from the wire to the weld pool. This type can produce a less stable arc and requires a higher voltage, making it suitable for thicker materials but potentially leading to more spatter.

Spray transfer, utilized at high currents, involves a fine mist of small droplets being propelled to the workpiece, which provides excellent penetration and a clean weld bead but requires a more sophisticated setup and higher heat input.

Pulsed spray transfer is a variation that alternates between high and low current, allowing for better control over heat input and penetration,