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.
Derby (About this soundlisten) DAR-bee) is a city and unitary authority area in Derbyshire, England. It lies on the banks of the River Derwent in the south of Derbyshire, of which it was traditionally the county town. Derby gained city status in 1977, and by the 2011 census its population was 248,700.
Derby was settled by Romans – who established the town of Derventio – Saxons and Vikings, who made Derby one of the Five Boroughs of the Danelaw. Initially a market town, Derby grew rapidly in the industrial era. Home to Lombe's Mill, an early British factory, Derby has a claim to be one of the birthplaces of the Industrial Revolution. It contains the southern part of the Derwent Valley Mills World Heritage Site. With the arrival of the railways in the 19th century, Derby became a centre of the British rail industry.
Derby is a centre for advanced transport manufacturing, being home to the world's second largest aero-engine manufacturer: Rolls-Royce. Bombardier Transportation are based at the Derby Litchurch Lane Works and were for many years the UK's only train manufacturers. Toyota Manufacturing UK's automobile headquarters is southwest of the city at Burnaston. To the east lies Nottingham, separated by the M1 motorway.