Why is it crucial to adjust the voltage and amperage settings in GMAW?

Adjusting the voltage and amperage settings in Gas Metal Arc Welding (GMAW) is essential for achieving proper penetration and minimizing defects in the weld. The voltage controls the arc length, while the amperage affects the heat input into the workpieces. If the settings are appropriately tuned, the welder can achieve a stable arc, ensuring that the molten metal properly fuses the base materials without causing issues like undercutting or excessive spatter.

When voltage is too high, it can lead to a wide, shallow weld bead with poor penetration, while low voltage could create a narrow bead that might not fuse properly. Similarly, amperage that is too low may not provide sufficient heat for a good weld, resulting in incomplete penetration. Conversely, too high of an amperage can burn through the material or lead to a weld that is too thick and uneven. Therefore, correct voltage and amperage settings are key to creating strong, reliable welds with minimal defects.

This understanding is critical for welders to produce high-quality work, which is why choice B is the correct answer.