What does burnishing do to shallow scratches in sheet metal?

Burnishing is a process that enhances the surface finish of materials, particularly in sheet metal applications. When it comes to shallow scratches, burnishing works by displacing the material at the surface, effectively smoothing out the irregularities caused by the scratches.

As the burnishing tool applies pressure, it compresses the metal, leading to a denser and smoother surface without removing material. This not only improves aesthetics by making the surface appear more uniform but can also enhance the metal's resistance to corrosion and fatigue by creating a more polished finish. Thus, burnishing serves to refine the texture of the metal, eliminating the visibility of shallow scratches and contributing to an overall improvement in surface quality.

This understanding helps clarify why the other options do not accurately represent the function of burnishing. For instance, while burnishing can make scratches less noticeable, it does not completely remove or fill them. Additionally, burnishing enhances rather than weakens the material, making it a beneficial process in maintaining the structural integrity of sheet metal.