Numerical control of machine tools

Having only appeared a few decades ago, numerical control (NC) technology is now making its mark on the world of machining. Designed to control the operation of a machine based on program instructions, without direct operator intervention during execution, it initially enabled a major step forward in the automation of traditional machine tools. As a result, lathes, milling machines, drilling and boring machines are now capable of producing quantities and quality that would have been unimaginable just a few years ago. NC is also at the origin of new multi-purpose machine designs, such as the machining center.

Today, with its ever-closer links to advances in microelectronics and information technology, NC is steadily increasing in performance and user-friendliness, while at the same time reducing in price and size. As a result, it is penetrating even the smallest companies and becoming accessible to all industrial sectors requiring positioning or trajectory-following processes.

This article provides a basic understanding of NC. After a brief historical review of its rapid evolution, the author goes on to justify its use and describes in detail the physical make-up of the machines equipped with it. The architecture of NC, the various procedures developed to program it and the many tools available to the operator to facilitate machine operation are also discussed, as are the various steps to be taken before acquiring a numerically controlled machine tool (NCMT). A final paragraph is devoted to the state of the art of NC and the next technological steps that will influence its evolution between now and the end of this century.