Editing Computer numerical control (section)

{{Short description|Computer control of machine tools}}
{{Redirect-multi|2|CNC|numerics|the field of computer science|numerical analysis|other uses}}
[[File:CNC machine.jpg|thumb|A CNC machine that operates on wood]]
[[File:Wheel Machining.jpg|thumb|CNC machines typically use some kind of coolant, typically a water-miscible oil, to keep the tool and parts from getting hot.]]
[[File:Cnc lathe.png|thumb|A CNC [[metal lathe]] with the door open.]]
'''Computer numerical control''' ('''CNC''') or '''CNC machining''' is the [[Automation|automated control]] of [[machine tool]]s by a computer. It is an evolution of '''numerical control''' ('''NC'''),  where machine tools are directly managed by [[data storage media]] such as [[punched card]]s or [[punched tape]]. Because CNC allows for easier programming, modification, and real-time adjustments, it has gradually replaced NC as computing costs declined. <ref>{{cite web | url=https://www.pcmag.com/encyclopedia/term/numerical-control | title=Definition of numerical control }}</ref><ref>{{Cite web|title=What Is A CNC Machine? |url=https://cncmachines.com/what-is-a-cnc-machine|access-date=2022-02-04|website=CNC Machines }}</ref><ref>{{cite encyclopedia |last=Groover |first=Mikell P. |date=2024-10-28 |title=Automation - Numerical Control, Robotics, Manufacturing |url=https://www.britannica.com/technology/automation/Numerical-control#ref390752 |access-date=2025-03-18 |encyclopedia=[[Encyclopædia Britannica]]}}</ref>

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, and 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) are generated. 3D printers also use G-Code.<ref name=":1">{{Cite web |date=2022-06-24 |title=What is CNC Milling and How Does it Work: Everything You Need to Know |url=https://www.3erp.com/blog/cnc-milling-everything-you-need-to-know/ |access-date=2025-03-18 |website=3ERP}}</ref>

CNC offers greatly increased productivity over non-computerized machining for repetitive production, where the machine must be manually controlled (e.g. using devices such as hand wheels or levers) or mechanically controlled by pre-fabricated pattern guides (see [[Pantograph#Milling machines|pantograph mill]]). However, these advantages come at significant cost in terms of both capital expenditure and job setup time. For some prototyping and small [[batch production|batch]] jobs, a good machine operator can have parts finished to a high standard whilst a CNC workflow is still in setup.

In modern CNC systems, the design of a mechanical part and its manufacturing program are highly automated. The part's mechanical dimensions are defined using CAD software and then translated into manufacturing directives by 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 several different tools – [[drill]]s, [[saw]]s, [[Touch_probe| touch probes]] etc. – modern machines often combine multiple tools into a single "cell". In other installations, several 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 meets every specification in the original CAD drawing, where each specification includes a tolerance.