Milling is the process of cutting away material by feeding a workpiece past a rotating multiple tooth cutter. The cutting action of the many teeth around the milling cutter provides a fast method of machining. The machined surface may be flat, angular, or curved. The surface may also be milled to any combination of shapes.The machine for holding the workpiece, rotating the cutter, and feeding it is known as the Milling machine.
Turning is the process of used to produce cylindrical components. A cylindrical piece of stock is rotated and a cutting tool is traversed along 2 axes of motion to produce precise diameters and depths. Turning can be either on the outside of the cylinder or one can perform inside diameter turning (also known as boring and drilling) to produce tubular like components to various geometries. A machine tool that performs turning is called a lathe.
Turning can also be used to produce features on a cylindrical component such as threads, worms, grooves and profiles. Turning is typically carried out using a single point tool made from high speed steel or sintered carbide. Hard materials can also be machined using ceramic tipped cutting tools. Other cutting tools used include parting tools, threading tools, centre drills, twist drills, dies, form tools, gnurling tools and grooving tools.
Manual milling and manual turning is still well suited to one-off jobs, small runs or where expensive fixturing is required.