Which of the following is NOT a common issue associated with MIG welding?

Improper gas usage is not commonly viewed as an issue specifically attributed to MIG welding when compared to the other listed problems. In MIG welding, shielding gas is crucial, and typically, the welder uses a gas mixture or pure gas that is appropriate for the material being welded. While using the wrong type of gas can lead to issues during welding, it is less often highlighted as a frequent problem in practice, as most MIG welding setups are standardized for the types of materials and processes involved.

In contrast, porosity in welds, inconsistent wire feed, and excessive spatter are frequent challenges that welders encounter. Porosity can occur due to contamination or insufficient shielding, negatively affecting the integrity of the weld. Inconsistent wire feed can lead to erratic arc stability and affect the quality of the weld bead. Excessive spatter results from improper settings or technique, which can complicate post-weld cleanup and affect the visual appearance of the weld.

Thus, while improper gas usage can indeed be problematic if not managed, it is not as prevalent an issue in the MIG welding context when compared to the other common problems mentioned.