CNC machines enable the production complex workpieces of consistently high quality and very large quantities. Very often one CNC machine can use different tools to perform various operations. Sometimes, the tools for CNC machines are called “heads”.
For this reason, mechanically controlled machines are now almost completely replaced by computer-controlled NC machines in industrial production. In detail, CNC machine control is automated with a computer software program. Manual programming is almost completely eliminated by modern CAM technology. The use of CAM software enables the automated conversion of 3D CAD data into a CNC program. Only machine parameters and tool data have to be entered into the program.
The division
All known conventional machine tools in mechanical engineering can be theoretically changed into CNC machines. The following list shows a selection of typical types of CNC machine tools:
- Machining Centre
- Milling machine, milling machines kits
- Lathe
- Grinding machine
- Laser cutting machine or CNC laser
- Water jet cutting system
- Engraving machine or laser engraving machine
- Drilling machine
- Band saw
- Plate shears
- Electrical Discharge Machine
- Sheet metal working machine
- Wire wrapping machine
- Wire spring winch machine
- 3D printer, 3D printer kits
- CNC Plotter
- CNC Router
In some cases, the above division may be arbitrary, due to the interchangeability of heads on some CNC machines.
Details
Some people misunderstood sometimes the term CNC router and plotter and see them as one and the same. The CNC router is designed for cutting and the plotter more for engraving using e.g. a laser, plasma, water, etc. You can create such a device also at home buying a special attachment for your already existing machine. We can observe a very fast development of the hobby-like CNC machine market. More and more people buy it for their home workshop. Companies as X-carve, Stepcraft, Axiom, Shapeoko and such that produces kits and attachments made it possible.
We can divide the CNC machines according to the prices and according to the proficiency of use. A hobby CNC machine has a relatively low price and some DIY it. The costs of a semi-professional device can reach a few thousands of dollars and the prices for professional machines can reach a really high level of costs.
Since CNC machines usually have high demands to accuracy and reproducibility, the frame and the machine bed are very rigid. This is achieved both by optimal structural design and by the right material selection (steel or mineral casting). The mechanical structure must be constructed as stiff as possible and with low vibration.
Axes
Typically, the CNC machine has 3 to 5 axes. Using the example of a CNC milling machine, the first 3 axes enable the movement of the workpiece in the 3 spatial directions (X, Y, and Z). An axis consists in each case of at least one high-precision CNC linear guide and a linear actuator. The CNC linear actuator is usually designed in the form of a ball screw or trapezoidal screw. The mechanics of the linear axes are often driven by highly dynamic servomotors or stepper motors.
The 4th axis is usually a turntable or turntable on which the workpiece can also rotate.
The 5th axis allows the milling head to pivot relative to the vertical. For optimum positioning accuracy, great efforts are made to design the linear drives without any backlash.
Source: Datulab Tech