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.NC machines had instructions fed into them in the form of punch tapes or punch cards carrying a series of points through which the controls would move, with the result that objects could be machined with more precision than when the machines were operated by hand.At first the geometric calculations to generate the points required to generate different shapes had to be worked out by hand by hand, which was a time-consuming process. This was a time-consuming and sometimes imprecise process, but with the advent of computer-generated punch tapes in the mid 1950s 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’ proposal to develop a programming language, based on points and lines, for numerical machine control. Over several years this language was developed into the Automatically Programmed Tools (APT) programming language, which was used in CNC machines until the 1970s. In 1957 a team led by researchers at MIT began working on a fully computerized numerical control system using the APT language. By 1959 the work of this pioneering team had produced the first product ever produced using computer-aided design and manufacturing – an aluminium ashtray.
The falling price and size of computing power in the 1960s meant that it became cost-effective to replace the dedicated servo systems controlling CNC machines with minicomputers.The development of microprocessors in the 1970s led to the widespread adoption of microprocessor control in CNC machines, and today almost all CNC machines are microprocessor-controlled.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 CNC 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.