What factor is primarily improved by a good surface finish in sheet metal structures?

A good surface finish in sheet metal structures primarily enhances corrosion resistance. When surfaces are smooth and free from imperfections, it minimizes the areas where moisture and corrosive agents can settle and initiate rust or degradation. A polished or well-finished surface has fewer crevices and micro-cracks, which are potential starting points for corrosion processes.

Additionally, an improved surface finish often involves coatings or treatments that further protect against environmental factors. While surface finish can have secondary effects on other properties, such as thermal conductivity or aesthetics, its most critical role is in maintaining the durability and longevity of the material by resisting corrosion.