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.
Leicestershire (/ˈlɛstərʃər, -ʃɪər/ (About this soundlisten); postal abbreviation Leics.) is a landlocked county in the English Midlands, being within the East Midlands. The county borders Nottinghamshire to the north, Lincolnshire to the north-east, Rutland to the east, Northamptonshire to the south-east, Warwickshire to the south-west, Staffordshire to the west, and Derbyshire to the north-west. The border with most of Warwickshire is Watling Street, the modern A5 road.
Leicestershire takes its name from the city of Leicester located at its centre and administered separately from the rest of the county. The ceremonial county – the non-metropolitan county plus the city of Leicester – has a total population of just over 1 million (2016 estimate), more than half of which lives in the Leicester Urban Area.
Leicestershire remains the only county in England other than Greater London that has yet to adopt an official county flag.