CNC machining uses subtractive processes, which means feedstock is machined to its final form by subtracting and removing material. Holes are drilled, lots and pathways are bored, and metal stock is shaped into new material with varying tapers, diameters, and shapes.

For subtractive manufacturing, shapes are achieved by the subtraction of material. This contrasts with other types such as additive manufacturing — where materials are added, layered, and deformed to a specified shape. It also contrasts with injection molding where the material is injected in a different state of matter, using a mold, and formed to a specified shape.

CNC machining is versatile — and can be used with various materials, including metals, plastics, wood, glass, foam, and other composite materials. This versatility has helped make CNC machining a popular choice across industries, enabling designers and engineers to fabricate products efficiently and precisely.