CNC machining is a manufacturing process during which the movements of tools and machines are followed by previously programmed computer software. The process can be used for controlling numerous complex machines from grinders to lathes. By CNC machining, three–dimensional cutting tasks can be performed in one series.
CNC is the abbreviation of „computer numerical control”. Thus it surpasses the limits of manual control where the operators should direct and control the command lines of the machining tools with handles, buttons and wheels. For the user, CNC system may resemble a regular computer component, but the software programs and consoles applied in CNC machining differentiate it from any other form of computing.
In the CNC system, the tools, machines are programmed through a software program how to perform the designing and cutting, just as a robot. In the numerical control system, the partial program means the series of inputs which controls the positioning of the tool. In this control system, the “program lines” are given by means of punch cards, while in the CNC machines small keys are found for entering the “program lines”. The CNC program is stored in the memory of the computer. The program code is certainly written, edited by programmers specialized in it. The CNC system makes huge numerical capacity possible; what’s more, the new commands can be added to the already existing programs by entering modified program code.
Numerical controlling machines were used in 1940 first; it means that existing tools were moved by engines. Owing to the technological development, the system was extended with analogous computers and then with digital computers, from which the CNC machining developed finally.
Nowadays, majority of the CNC systems are fully electronic; the most frequently applied CNC procedures are punching, welding and laser cutting. In the following, we will describe in details the machines most frequently used in CNC systems.
CNC milling is the most frequent computer control (CNC) machining, performing the functions of both the drilling machines and turning lathes. The programming used for the machine can be based on the G-code or the unique language developed by the manufacturing group. The basic machining centres consist of a 3-axis (X, Y and Z) system, although the new machines are already able to manage further three axes. CNC machines are categorized on the basis of their axis number, and traditionally can be programmed by such code sets which represent specific functions.
In lathes, the pieces are cut in circular direction with indexable tools. Through the CNC technology, the cuts used by the lathes can be performed precisely and at high speed. CNC lathes are used for the production of such complex designs which cannot be manufactured by manual run of the machine. The controlling functions of CNC machines and lathes are basically similar. Similarly to the former, the lathes can also be controlled by G-code or individual code. However, majority of CNC lathes consist of two axes - X and Z.
In plasma cutters, the material is cut by means of plasma torch. The procedure is applied mainly for metal materials, but it is applicable for other surfaces as well. In order to achieve the speed and heat necessary for cutting the metal, the plasma is produced by the necessary combination of compressed air and electric arches.
Fiber is a kind of laser for cutting solids, the application of which quickly increases in metal industry. Contrary to the CO, Fiber technology uses solid medium instead of gas or liquid. The “MAG LASER” produces the laser beam, which is then amplified in a glass fibre. It is ideal for cutting reflecting metal materials. This is a main advantage of Fiber as compared to the CO.
Since CNC is used for cutting metal pieces of industrial hardware products extremely in details, in addition to the examples mentioned above, CNC technology can be used also for the following:
If complicated cuts are to be made on the work piece on various levels and at various angles, then it can be performed on any CNC machine.
Milling means machining done by turning and cutting machines which serves for removing the material. This process is done on one or several axes through the speed of the cutting head and the pressure applied in variable directions. Milling comprises wide range of various operations and machines, from small or large to even high-capacity milling operations. This is one of the most frequently applied procedures for machining high-accuracy tolerances of individual parts.
Milling can be done with wide range of machine tools. The machine tools used for milling are the milling machines (referred to as mills as well). Owing to the spread of the CNC technology, milling machines changed to machining centres. Milling centres are usually VMCs (vertical machining centres) or HMCs (horizontal machining centres).
It may be necessary to integrate milling into turning environment and vice versa: milling tools can be used for turning operations as well. It results in a new machine class the purpose of which is to facilitate milling and turning on the same work sheet.
During milling, milling tool is used for removing material from the surface of the piece. With the milling machine, the cutting is done with the surface of the cutting tool. Contrary to the drilling, the tool does not run along the line of the rotational axis. When the milling tool touches the piece, the cutting edges of the cutting tool cut the material and at the same time remove the chips while passing through. Cutting edges are called also flutes or teeth. The material pushed out in clusters will form chips.
Through the milling process, a lot of separate materials can be produced by small cuts. It is done by using such tool which contains a lot of teeth, so rotating it at high speed, the material passes through the cutting tool slowly. The speeds used are adjusted to the combination of variables. The speed at which the piece passes the cutting mechanism is called advance. The length of material is measured during the whole revolution number of the cutting machine.
Why is CNC milling useful?
Digital technologies and CNC milling machines solve numerous such problems which could not be solved previously. Owing to the approach applied by the technology, the working process is much more efficient than any other procedure.
For example, cutting of metal for car parts or even airplane parts would be much more risky without a CNC milling machine. With the support of computer programs we can create high-resolution drawings, which can easily be converted into coordinates. This process will even decrease the extra costs incurred during the manufacture of prototypes.
However, these technological machines do not serve only for industrial use. Several further fields where CNC milling can be applied:
© 2024 - Nyírlift Kft. www.nyl.hu