CNC is computer numerical control machining, is a widely used manufacturing process that uses automated, high-speed cutting tools to form designs from metal or plastic stock. Standard CNC machines include 3-axis, 4-axis, and 5-axis milling machines, lathes, and routers. Machines may vary in how CNC parts are cut—the workpiece may remain in place while the tool moves, the tool may remain in place while the workpiece is rotated and moved, or both the cutting tool and workpiece may move together. Skilled machinists operate a CNC machine by programming tool paths based on the geometry of the final machined parts. The part geometry information is provided by a CAD (computer-aided design) model. CNC machines can cut almost any metal alloy and rigid plastic with high precision and repeatability, making custom machined parts suitable for nearly every industry, including aerospace, medical, robotics, electronics, and industrial.