Computer numerical control (CNC) machines are the manufacturers best friend. CNC tooling is the process by which a computer automates the machining process to guarantee the same result every time. This makes CNC machines ideal for mass production.
CNC machines are able to move along a line or circular trajectory, thus providing 2D and 3D contouring. Their multiple axes are capable of simultaneous motion; to endmill in a circular trajectory, for instance, requires the machine to move simultaneously along both the X and Y axes. The machine can also move its cutting tool simultaneously along the X and Z axes, such as around the corner of a part to produce a fillet.
CNC milling machines cost around