The initial concept for CNC machine tools was developed in 1952 by the Massachusetts Institute of Technology (MIT) in the United States, who developed a three-axis CNC milling machine. By the mid-1950s, this type of CNC milling machine was already being used to machine aircraft parts. In the 1960s, CNC systems and programming became increasingly mature and sophisticated, and CNC machine tools were used in various industrial sectors, but the aerospace industry remained the largest user. Some large aerospace factories were equipped with hundreds of CNC machine tools, primarily cutting machines. CNC-machined parts include integral panels, beams, skins, bulkheads, propellers, and mold cavities for aircraft engine casings, shafts, discs, and blades, as well as special cavity surfaces for liquid rocket engine combustion chambers. Early development of CNC machine tools focused on continuous trajectory control.
Continuous trajectory control, also known as contour control, requires the tool to move relative to the workpiece along a predetermined trajectory. Later, point-to-point control CNC machine tools were developed extensively. Point-to-point control refers to the tool moving from one point to another, as long as it accurately reaches the target, regardless of the specific path taken.
