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 for numerical machine control that was based on points and lines. This language was developed into the Automatically Programmed Tools (APT) programming language, which was used to program 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 their work had resulted in 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. 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 machining has found roles far more diverse than the spindle and cutting tool processes in which it has its roots, and today CNC can be used for any process suitable for machine tool motion platforms. These include lasing, welding, flame cutting, bending, spinning, pinning, gluing, fabric cutting, sewing, routing, and sawing.
If you enjoyed this post, make sure you subscribe to my RSS feed!