CNC
CNC (also computer numerical control, or numerical control) is the automated control of machining tools (such as plasma cutters, mills, drills, lathes, and 3D printers) by means of a computer. CNC machines process a piece of material (metal, plastic, wood, ceramic, or composite) to meet specifications by following coded programmed instructions (without a manual human operator) directly controlling the machining operation.
CNC machines are motorised manoeuvrable tools and often a motorised manoeuvrable platform, which are both controlled by a computer, according to specifically programmed input instructions. These instructions are delivered to CNC machines in the form of a sequential program of machine control instructions such as “G-code” and “M-code”, and then executed. The program can be written by a person or, far more often, generated by graphical computer-aided design (CAD) tool/software and/or computer-aided manufacturing (CAM) tool/software. In the case of 3D printers, the part to be printed is "sliced", before the instructions (the program) is generated. 3D printers also use “G-code”.
CNC is a vast improvement over non-computerised 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 mechanical parts and their manufacturing programs are 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 manufactured components and then are loaded into and executed by the CNC machine.
Since any particular component might require the use of a number of different tools, e.g. drills, saws, etc., modern CNC 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 produce parts that closely match the original CAD drawing/specification.