Which process alters the surface of a manufactured part for desired characteristics?

Finishing is the process that alters the surface of a manufactured part to achieve desired characteristics such as smoothness, appearance, corrosion resistance, and dimensional accuracy. This can involve various techniques, including polishing, painting, coating, and heat treating, which enhance the functionality and aesthetics of the part. The aim of finishing is to create a high-quality final product that meets specific performance and visual standards, thereby ensuring the part performs effectively in its intended application.

The other options represent different stages or types of manufacturing. Casting involves pouring liquid material into a mold to form a specific shape, shaping refers to altering the bulk material's geometry to achieve desired dimensions, and additive manufacturing refers to building up material layer by layer to create a part. While these processes are critical in the initial creation of parts, they do not specifically address the alteration of the surface for enhanced characteristics, which is where finishing plays a pivotal role.