CNC machining, shorthand for “Computer Numerical Control” machining, can be traced back to machines created during the mid-1940’s to the 1950’s.
Early (pre “computer”) “NC machines” were built based on existing machining tools with modified motors that moved the tool or part to follow points defined and fed to the system on punch tapes. (Yep. Punch tapes
John T. Parsons, together with Frank L. Stulen, pioneered CNC when they devised a method for machining the curves of helicopter blades, a/k/a “rotors”. They generated numbers for complex and precise machining system outputs, subsequently turning to Gordon S. Brown’s Servomechanisms (“servos”) Laboratory at MIT to develop a feedback system capable of guaging how far the controls, i.e., milling or cutting tools, had actually progressed.
The arrival of CNC machining greatly reduced production times, so much so that the U.S. Air Force funded a proposal to produce a generalized “programming” language for NC. Eventually, the Air Material Command at the Wright-Patterson Air Force Base and the Aircraft Industries Association (AIA) collaborated with MIT to create a fully computer controlled NC system.
Although modern CNC machines have integrated advanced computing algorithms and A.I. their essential functions mirror much like earlier machines to produce three dimensional outputs along X and Y axes, and depth.
Wikipedia presents a concisely detailed history of numerical control.