Which of the following is primarily used for final touches on metal parts to achieve smoothness?

The finishing operation is primarily focused on refining metal parts to achieve a high level of smoothness and surface quality. This process may include techniques such as grinding, polishing, or buffing, which are specifically designed to remove the last few microns of material and enhance the appearance and texture of the metal surface. Finishing operations are crucial in applications where surface integrity is pivotal, such as in automotive, aerospace, and precision instrument manufacturing.

Turning, while it plays a significant role in shaping and removing material, often yields a surface that requires further finishing to achieve the desired smoothness. Drilling is primarily used for creating holes and does not typically contribute to surface smoothness in the way that finishing does. Forming involves reshaping metal without cutting, which does not address surface finish in the same manner as finishing operations. Thus, completing a part with a finishing operation ensures that it meets the necessary specifications for surface quality and appearance.