The History of CNC

WWII, and the onslaught of the industrial revolution, brought about the “Computerized Numerical Control” or CNC as it is referred to in present day.

Largely due to the onslaught of aircraft utilization, there was a need and desire to create and produce complex parts with more accuracy.

In 1996, the summer issue of American Machinist articulately explains the history of CNC, and we felt it well worth the share…

Numerical control as a concept developed in the mind of John Parsons as a way to produce integrally stiffened skins for aircraft, and this led to a series of Air Force research projects at the Massachusetts Institute of Technology, beginning in 1949.

The initial planning-and-study phase was followed by the construction of an experimental milling machine at the Servomechanisms Laboratory at MIT. Prof J.F. Reintjes, director of the lab, James O. McDonough, Richard W. Lawrie, A.K. Susskind, and H.P. Grossimon were the people involved in the research.

A 28-in. Cincinnati Hydro-Tel vertical-spindle contour milling machine was the starting point. It was extensively modified: all of the table, cross-slide, and head drives and controls were removed, and three variable-speed hydraulic transmissions were installed and connected to lead screws. Each transmission would produce, through gearing and lead screw, a 0.0005-in. motion of the table, head, or cross-slide for each electrical pulse received from the director. A feedback system was provided to make sure the machine was doing what it was told. A synchronous motor geared to each motion generated a voltage response to movement; this was sent back to the director and compared with the original command voltage.

By 1951, the system had been assembled, and application studies were begun. By 1953, enough data had been assembled to indicate practical possibilities that could be developed. A detailed 24-page report on the process that appeared in American Machinist on Oct 25, 1954, started a flurry of further development. […] But it was the initially more awkward, less accurate prototype at MIT, which employed a Flexowriter and its eight-column paper tape, a tape reader, and a vacuum-tube electronic control system that was to become the prototype for the developments that followed.

Parsons Corp. [founded by John T. Parsons, who had been introduced earlier in the article] had already developed a system for producing helicopter-blade templates by calculating airfoil coordinates on an IBM 602A multiplier and feeding these data points into a Swiss jig borer—rather than laying out the job manually […] Late in 1948, the Air Force sent a team to the Parsons plant in Traverse City, Mich. There they saw the technique being used in producing templates from data on punched cards.

For such significant technical contributions to the field of numerical control, John T. Parsons in 1968 became the first recipient of the Numerical Control Society’s Joseph Marie Jacquard Memorial Award. And in 1975, the Society of Manufacturing Engineers awarded him a plaque naming him ‘The Father of the Second Industrial Revolution.’