The Development Of Precision CNC Machine Tools

The history of Computer Numerically Controlled (CNC) machining begins with the early numerically controlled machines, which were servomotor controlled tools that were able to machine precise shapes.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 to formulate a general programming language for numerical machine control that was based on points and lines.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 began developing 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. In the 1970s, the development of microprocessors led to microprocessor-controlled CNC machines becoming more common, and today almost all CNC machines are controlled by microprocessors. To some extent USB drives, floppy disks and local area networks have replaced punch tapes in modern CNC systems, however punch tapes are still widely used.

Modern CNC precision machining 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.CNC-controlled lasing, welding, flame cutting, bending, gluing, sewing, routing and sawing processes, amongst others are commonplace.

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