Today’s Computer Numerically Controlled (CNC) machines have their origins in early numerically controlled (NC) machines, servomotor controlled tools able to machine precise shapes by following instructions fed into them on magnetic or paper tape or punch cards. These instructions took the form of a series of points through which the controls would move, with the result that geometric forms could be machined far more precisely than if the machines were operated by hand. Production of these input media initially required complex calculations to be worked out by hand, in order to determine the points through which the NC machine had to move to machine a particular geometric shape. This was a time-consuming and sometimes imprecise process, but in the mid 1950s computer subroutines were developed to carry out these calculations, and the era of computer numerical control (CNC) had arrived. Computer generation of NC input media was so much quicker and more efficient than manual production that in 1956 the US Air Force accepted Douglas T.Ross to formulate a general programming language based on points and lines for numerical machine control.By the late 50s this language was developed into the Automatically Programmed Tools (APT) programming language, which was still in common use in CNC machines until the 1970s.In 1957 MIT researchers led a team aimed at developing a fully computerized numerical control system using the new APT programming language. By 1959 their work had resulted in the first product ever produced using computer-aided design and manufacturing – an aluminium ashtray.
As computers became smaller and cheaper over the course of the 1960s, it became cost-effective to replace the dedicated servo systems controlling CNC machines with minicomputers. In the 1970s, the introduction of the microprocessor led to microprocessor-controlled CNC machines becoming more widespread, and today almost all CNC machines are controlled by microprocessors.USB drives, floppy disks, local area networks, and other modern storage media have to some extent replaced punch tapes in modern CNC systems, however punch tapes are still widely used.
Modern precision engineering has diversified from the spindle and cutting tool processes for which it was originally developed, and today CNC can be used for any processes that can be carried on machine tool motion platforms. These include lasing, welding, flame cutting, bending, spinning, pinning, gluing, fabric cutting, sewing, routing, and sawing.
