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06/20/2022

CNC and NC - history and importance of (computer) numerical controls

For a long time, workpieces were created by direct and freehand guidance of a tool by a human being. This type of production was replaced by machine tools, i.e. machines that guided the tool path and thus set new standards in precision and efficiency. When concepts of programmable logic of tool guidance were first introduced in the automation of such machine tools, the history of numerical control (NC) began. With an increasing market demand in the second half of the last century, this new NC technology also experienced a sustained growth spurt - until it was superseded by CNC technology. Today it is impossible to imagine the world of manufacturing without it.

The programmable machine tool

The first machines with NC control were created in the 1940s and 1950s from existing machine tools, modified with motors that could move controls to follow points fed into the system on punched tape or magnetic tape. To do this, the NC control used an abstraction of the object to be created in the form of a mathematical model and corresponding instructions to the machine.

The aim was to precisely determine the motion sequence of a machine tool automated in this way and thus achieve new accuracies on the workpiece. This was because the manual guidance of the tools could not meet the ever-increasing manufacturing requirements that aviation and other industries were placing on them.

During the ongoing attempts to retrofit the existing machines, it became clear that NC technology and machine designs are closely linked. More and more specially developed and built NC machines with more stable designs and components geared to the new requirements came into being. In the industrialized countries of Europe, the first NC machine celebrated its market launch in 1959.

TODAY, THE AMERICAN INVENTOR JOHN T. PARSONS (1913-2007) IS WIDELY CONSIDERED THE FATHER OF NUMERICAL CONTROL. PARSONS HOLDS THE FIRST NC PATENT AND WAS INDUCTED INTO THE NATIONAL INVENTORS HALL OF FAME FOR HIS PIONEERING WORK IN NUMERICAL CONTROL. 

From the NC to the CNC machine

Punch card
The punch card was used to store data

At the end of the 1970s, the increasing use of microprocessors instead of punched cards and magnetic tapes ushered in the CNC era. While the basic principle of automated tool guidance remained unchanged, computer numerically controlled machines were able to send even more precisely coded instructions from a microprocessor to the control of a machining tool.

Numerical controls were completely replaced by computer numerical control as development progressed. After only a few years, CNC had already established itself in the machine tool industry. Machining thus also became one of the first practical applications of computer technology.

In terms of manufacturing technology, the technological boundaries have continued to shift ever since. Automated tool and pallet changers, flexible manufacturing systems and increasingly individualized automation solutions have accompanied the progressive development of NC and subsequent CNC machines since their inception. Today, it is not uncommon for projects to reach the limits of economic viability much sooner than the limits of technical feasibility.

CAD and CAM as mediators between man and CNC machine

CNC controlled machine
The Gildemeister NEF was an early CNC controlled machine

For many years, the programs for use on CNC machines were still created manually. A high effort, especially since any errors in the demanding programming could mean expensive damage to the machine. Thus, the world of manufacturing increasingly developed in the direction of computer-aided design (CAD) and manufacturing (CAM) programs.

CAD programs allow you to digitally create, modify and approve a 2D or 3D object. CAM programs allow you to select tools, materials and other variables for your cutting job. After all, once created in CAD, the machine does not yet know the size and shape of the cutting tool or the material size or type.

CAM programs therefore use the CAD model to calculate the movement of the tool through the material. These tool paths are automatically generated by the CAM program to achieve maximum efficiency. Today, CAM programs can also create simulations of subsequent machining. These simulations save tool wear, machining time and material.

It is therefore impossible to talk about the development from NC to modern CNC machines without also honoring the accompanying software development, which made digital design steadily accessible across the board.

Pioneer in the development of CNC-controlled machines

Modern CAD and CAM systems form the interface between people, ideas and finished components

DMG MORI has had a decisive influence on the development of NC and CNC controls from the very beginning. The control range has been continuously expanded over the following decades and today includes state-of-the-art controls from Siemens, Heidenhain, FANUC and MAPPS. This makes DMG MORI the only machine tool manufacturer in the world that equips its machines with the CNC controls of the four largest suppliers - and can thus also meet almost all of its customers' preferences.