The term CNC control refers to both a material processing method and a component in specialised milling machines. The abbreviation stands for the English words "Computerized Numerical Control". These words are translated as "numerical computer control". However, CNC control has also become a common translation, although the English vocabulary reappears as an abbreviation.
CNC control as a material processing method
CNC control is a material processing method that gives the computer control over the machine that executes it. It is a multi-axis milling machine. Three or five axes are widely used. However, modern machines can also have more than six axes.
The actual process follows the following steps:
1. a suitable model is created with a suitable CAD programme.
2. the CAM (Computer Aided Manufacturing) system receives the model and guides the machine.
3. the numerical computer control system calculates and transmits commands for the milling machine in order to implement the model as precisely as possible.
4. the system works according to the principle of material removal. This means that what is not necessary for the model is removed. In this way, it is avoided that several workpieces have to be brought together.
The process is particularly suitable for creating prototypes of small quantities. Otherwise, it is too costly compared to the vacuum casting process. Via CNC control, for example, models can be created for functional tests. In this way, developers can find out whether they have chosen suitable material for a component, for example.
The CNC control as a component
Machines for CNC machining essentially consist of five components:
1. milling machine
2. power supply
3. work surface
4. programmable logic controller (PLC)
Strictly speaking, only the CNC is the control system that is the subject of this article. Often, however, the PLC is also considered to be part of it. However, it is actually the connection between the CNC control and the milling machine. The PLC receives the movement commands for the milling machine and forwards them in the correct order.
The special feature of the CNC control is its ability to calculate and pass on three-dimensional commands. This differs from other comparable components that work by means of computers. The term "numerical" is significant here. The control works with a coordinate system that consists of at least X, Y and Z axes. Here, the coordinates of individual points of the model are noted numerically - including the angles. Based on this data, the control can also determine, for example, how long a cut has to be made - or when the tool has to be changed.