The abbreviation CNC stands for Computerized Numerical Control. Defined according to DIN 66257, the term CNC technology refers to "numerically controlled working machines". This refers to computer-based automation technology in which the machine is controlled with the aid of a computer system. CNC technology is therefore closely related to industrial robotics.
The 1960s saw the emergence of the first numerical controls for machine tools. During the 1970s, these numerical controls (NC) evolved into computerized numerical control (CNC) systems. The use of computer technology significantly increased productivity, which also increased the demands on users.
CNC technology enables machines to take over various manufacturing applications such as machining, forming or ablation. Thus, CNC technology makes an important contribution to improving workflows in manufacturing technology.
The use of CNC technology is very widespread. The reason: The control technology offers the possibility to automatically produce workpieces or components from many different materials. Using tailored computer solutions (CNC programming), CNC machines are able to machine, form or remove these materials.
The computer solution is composed of an operating system and a user interface. One works with a system for computer-aided manufacturing, a so-called CAM (Computer Aided Manufacturing). The required data comes from a CAD program (Computer Aided Design), which designs the components in advance and runs automated processes instead of manual drawing. This is followed by the transfer of the data to the CAM system.
CNC machines and thus their range of applications can be expanded by various accessories. Typical accessories are, for example, milling cutters, engraving gravers, clamping devices, grooving plates, rotary axes or 3D scanners.
There are three different control types for CNC technology:
This control method is mainly used for machine tools and in robotics. As the name suggests, the point-to-point method defines an end point so that the respective target can be approached directly.
PTP controls can be divided into synchronous and asynchronous variants. While the axes reach their destination at the same time in the synchronous application, they have different speeds in the asynchronous control and therefore reach the destination at different times.
Draw frame control is similar to PTP control, but the methods differ with regard to the speed of movement of one of the axes. With path control, axis-parallel movements are possible, and the position can also be determined precisely. In addition, the axis tool can move along the workpiece and thus mill a straight slot, for example.
With path control, several axes can be moved at the same time. The course and speed of the control are precisely defined.
The various processes of CNC technology are used for CNC machining in machines in toolmaking, mold and model making, and engraving. CNC technology is therefore used in many industrial sectors. These include, above all, mechanical engineering, the automotive and aerospace industries or shipbuilding. The jewelry and toy industry or medical and dental technology are also important areas of application.
CNC technology is mostly used for the production of small series, individual parts or prototypes. For CNC machining, mainly metals (including copper, aluminum, brass, carbon steel, stainless steel) and plastics (including polyethylene, PET, PMMA, PVC) are used, but also wood.
Various methods are available for CNC machining, depending on the area of application and the desired result:
CNC milling: Milling tools, so-called milling cutters, are used in CNC milling. These milling machines perform chip-removing work on various materials. Unlike other tools, the milling cutters are firmly clamped (on a milling machine) and perform rotating movements. Since CNC milling machines perform their tasks completely independently, they do not require constant human supervision. Even quality control and monitoring of wear – for example of industrial spare parts – and tool breakage can be taken over by the machine.
CNC turning: With the help of CNC turning, workpieces are brought into specific shapes with computer support and automation (machining). The method is mainly used in the metal and plastics processing industry. The results of turning are rotationally symmetrical workpieces. The process offers the advantage of very high repeatability and thus – especially for series production – high cost-effectiveness.
CNC drilling: CNC drilling is a technique of drilling holes in a workpiece. Here, too, it has the advantage of high accuracy and reproducibility of the work step.
CNC optical glass processing: The techniques of optical glass processing are diverse. CNC machines can be used to cut, drill, grind, polish and more optical glass.
CNC technology offers numerous advantages in almost all application areas and industries. The respective processes precisely meet the requirements that medium-sized, but also large companies place on a production process. The various processes are used both in the automotive industry and in mechanical and plant engineering as well as for the production of very small parts – for example for electrical and medical engineering. Both large and small batches are economically viable.
We have summarized further advantages of CAD and CNC technology below:
High precision in the production of workpieces: Data can be transmitted from the computer directly to the CNC machine. This makes manufacturing far more accurate and produces results that would not otherwise be possible. CNC machines are even capable of producing components with interwoven shapes (two- or three-dimensional) whose individual elements are virtually identical.
Saving production costs and resources: the use of CAD/CAM software eliminates the need to repeatedly reprogram the machine. The human workforce is thus relieved. In addition, material scrap is very low with high-precision CNC machining. As a result, production costs decrease and there is less material waste.
Simplifying product diversification: CNC makes it much easier to manufacture new products. This is partly due to the flexibility of CNC-controlled machines, and partly due to the simplified production compared to conventional manufacturing processes.
Automation of production: with CNC technology, it is possible to produce different workpieces with one machine without having to retool it. To start the CNC machine, it is usually enough to clamp the material. The machine then carries out the respective work steps completely independently. This eliminates the need to reclamp materials; instead, a simple change of program is all that is required. This saves time and thus costs.
Whether in the automotive industry, in mechanical and plant engineering, or in medical technology: Numerous industries rely to a large extent on CNC technology in manufacturing. The reason: CNC machines are unsurpassed in terms of precision when it comes to producing milled parts, markings or engravings. Typical areas of application are CNC milling, drilling, turning and CNC glass processing.
