CNC Technology, What is it?



Henry Ford championed the second industrial revolution in 1908 - 1915 with his Model T Ford and assembly line manufacturing.

Part of this second industrial revolution was to place the worker in control of the machine instead of actually performing the task. To the house person this may mean the use of an automatic washing machine or to the factory worker the control of an automatic production process.

In the manufacturing industry, engineers have been striving to produce more efficient automatic machines, the initial requirement was to speed up the operation and produce long production runs of the same component while maintaining accuracy and keeping the cost down to a minimum.

These machines ranged from cam operated automatics, through to plug board sequence control machines.  However these machines, though advanced for their day required lengthy setting up.

The development of the sequence control machines led to the Numerical Control (NC) machines.  These were controlled by reading in each instruction from punched paper tape/punched card, then carrying out the instruction before reading the next instruction.  The obvious disadvantage of this being the tape must be read for every work piece produced, so in time the tape and mechanical tape readers became worn.

Computers were introduced to store the list of instructions (program) and control the machine.  Initially a large computer was used to control several machines (main frame system).  This system known as Direct Numerical Control (DNC) was used in general by larger organizations as computers were expensive, with one DNC computer being able to control up to 256 machines.  The main disadvantage with this system was that if the DNC computer broke down all the NC machines would have to stop as well meaning a loss of production would occur.

The development of the mini or micro computer allowed the possibility of having a dedicated computer control for each individual machine, this system is known as Computer Numerical Control (CNC).  To- day CNC tools are configured in a variety of types, ranging from Lathes, Drills, Bending machines, Punching machines, laser cutting machine tools to large machining centres.

All these meachine can then be linked back to a main frame type system which loads storted part programmes down to the local machine tool part when requested by the machine tool manager. This type of DNC system is known as Distributed Numerical Control.

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