Numerical control (also computer numerical control, and commonly called CNC) is the automated control of machining tools (such as drills, lathes, mills and 3D printers) by means of a computer. A CNC machine processes a piece of material (metal, plastic, wood, ceramic, or composite) to meet specifications by following a coded programmed instruction and without a manual operator directly controlling the machining operation.
A CNC machine is a motorized maneuverable tool and often a motorized maneuverable platform, which are both controlled by a computer, according to specific input instructions. Instructions are delivered to a CNC machine in the form of a sequential program of machine control instructions such as G-code and M-code, then executed. The program can be written by a person or, far more often, generated by graphical computer-aided design (CAD) or computer-aided manufacturing (CAM) software. In the case of 3D printers, the part to be printed is "sliced", before the instructions (or the program) is generated. 3D printers also use G-Code.
CNC is a vast improvement over non-computerized machining that must be manually controlled (e.g. using devices such as hand wheels or levers) or mechanically controlled by pre-fabricated pattern guides (cams). In modern CNC systems, the design of a mechanical part and its manufacturing program is highly automated. The part's mechanical dimensions are defined using CAD software and then translated into manufacturing directives by computer-aided manufacturing (CAM) software. The resulting directives are transformed (by "post processor" software) into the specific commands necessary for a particular machine to produce the component and then are loaded into the CNC machine.
Since any particular component might require the use of a number of different tools – drills, saws, etc. – modern machines often combine multiple tools into a single "cell". In other installations, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD drawing.
Worcester (/ˈwʊstər/ (About this soundlisten) WUUS-tər) is a cathedral city in Worcestershire, England, 30 miles (48 km) south-west of Birmingham, 101 miles (163 km) west-north-west of London, 27 miles (43 km) north of Gloucester and 23 miles (37 km) north-east of Hereford. The population is about 100,000. The River Severn flanks the western side of the city centre, which is overlooked by Worcester Cathedral. The Battle of Worcester in 1651 was the final one in the English Civil War, where Oliver Cromwell's New Model Army defeated King Charles I's Royalists. Worcester is the home of Royal Worcester Porcelain, composer Edward Elgar, Lea & Perrins, makers of traditional Worcestershire sauce, University of Worcester, and Berrow's Worcester Journal, claimed as the world's oldest newspaper.