Computer numerical control (CNC) milling can be traced back to the 1940s, long before the computer technology was available to perform the high-tech process that is integral to manufacturing today.
It was the United States Air Force with the help of the Massachusetts Institute of Technology that developed NC (numerical controlled) milling for the purpose of finding a way to more efficiently manufacture airplane parts. It was John T. Parsons who is credited with creating NC milling. He was head of the Rotary Wing Branch of the Propeller Lab at Wright-Patterson Air Force Base.
NC milling revolutionized many aspects of manufacturing. By the 1960s, computers had advanced enough to make true CNC milling a reality. This method involves using computers to control rotating, multi-point cutting tools – such as drills using CNC milling machine bits – to remove materials from a piece to make a super accurate custom-designed final product.
The method can be used for just about any material, including metals, plastics, wood and glass.
A CNC milling project begins by making a 2D or 3D computer created design, or CAD. The file for the CAD is exported to a CNC file and converted by special software into a CNC program. This will control the actions and basically direct what the drilling, cutting, shaping and material removal process the machine will perform. For drilling work, machines are fitted with specially designed CNC milling machine bits.
The CNC milling machine is prepared by an operator by affixing a work piece to a surface – or to sometimes what is called a work-holding device. The stage is now set for the CNC milling process to begin. Now all the operator needs do is punch “enter” on a keypad and the machines goes to work!
The most common CNC milling functions are face milling, plain milling, angular milling and form milling.