The History of CNC Machining

From punched tape to today's methods

12
Jul

The History of CNC Machining

Although humans have been using tools to harness and accentuate power for 2.6 million years, the true machining development came with the industrial revolution. The industrial revolution commenced in the 18th century, and was a reformation of the manufacturing industry. With the introduction of machines, the potential production rate skyrocketed whilst the production time was drastically minimised. During this time, employment rates in factory work were on the rise, as were the work hours. It wasn’t until 1833 that the Factory Act enforced capped work hours for children, setting a standard for factory work and subliminally marking an acknowledgement of the level of human demand.      

Punch tape method

Despite the substantial leap forwards in terms of quality and uniformity in manufacturing, there was still room for human error, as a result of the level of input required by factory workers. This bore the idea of a completely automatic numerically controlled machine line so as to relieve the requirement for so much human input and supervision. The first conception of this notion was established by John T Parsons, who developed the idea of Numerical Control machines using punched tape. This was a way to store numerical data by punching holes in long tape, read by paper tape reader and translated to machines for the instructed work to be carried out. In 1949 the Air Force funded Parsons to bring to life this first draft of NC machining, creating a machine with motorised axes to aid the production of helicopter blades, programmed by the punch tape method. Not long after, MIT collaborated with Richard Kegg to conceive the first numerically controlled milling machine.   In 1955, the punch tape method evolved to use a magnetic tape reader and more versatility in machine functions. This process began with planner sheet where the direction variable such as speed, cooling control and feeds, etc., could be entered. Then, instructions were input via keyboard into a unit which converted the information from decimal form into a plastic tape. Parity checks informed the system of any incorrect readings and another system would check that the parity system was functional. The tape was then fed into a digital reading unit which translated the information into a computer, whereby the computer would send instructions to the machines to direct them in the execution of tasks.      

The rise of the CNC machine

The introduction of digital technology in the 1960s and 1970s forged numerical control machines more similar to those we use today: CNC (computer numerical control) machines. This marked the evolution from punched tape to digital software, which operates under the same principals as NC machining but has more capacity for technological advancement. The software which replaced punch tape is referred to as CAD (computer aided design) software and, after some updates and retrofitting, is what we use today. CAD software allows (people) to create a blueprint on a computer which is translated into a CNC –legible format called g-code, which directs the CNC machine to operate across specific axes and motions. CAD software allows for accelerated production of designs, easier revisions and the capability for endless software revisions and updates, ensuring that CNC machining is a sustainable and forward-thinking manufacturing investment.