In digital dentistry,the construction data produced with the CAD software are converted into milling strips for the CAM-processing and finally loaded into the milling device,we uauslly distinguished the processing devices by means of the number of milling axes:
a) 3-axis milling devices
This type of milling device has degrees of movement in the three spatial directions. Thus, the mill path points are uniquely defined by the X -, Y -, and Z – values . The calculation investment is therefore minimal. A milling of subsections, axis divergences and convergences, however, is not possible. This demands a virtual blocking in such areas. All 3-axis devices used in the dental area can also turn the component by 180° in the course of processing the inside and the outside. The advantages of these milling devices are short milling times and simplified control by means of the three axes. As a result, such milling devices are usually less costly than those with a higher number of axes.
Examples of 3-axis devices: inLab (Sirona), Lava (3M ESPE), Cercon brain (DeguDent).
b) 4-axis milling devices
In addition to the three spatial axes, the tension bridge for the component can also be turned infinitely variably . As a result it is possible to adjust bridge constructions with a large vertical height displacement into the usual mould dimensions and thus save material and milling time.
Example: Zeno (Wieland-Imes).
c) 5-axis milling devices
With a 5-axis milling device there is also, in addition to the three spatial dimensions and the rotatable tension bridge (4th axis), the possibility of rotating the milling spindle (5th axis) . This enables the milling of complex geometries with subsections, as for example, lower jaw FPDs on converging abutment teeth (end molar tipped towards the medial plane), or also crown and FPD substructures that, as a result of anatomically reduced formation, demonstrate converging areas in the exterior of the frame.
At least a 4 milling axis is required for the milling unit to fabricate a substructure for this situation.
However, 5-axis machining is also becoming more popular because it offers the option for single-step machining (reducing lead time), allows better access to part geometry, and improves the tool life and efficiency of the process by tilting the table for the ideal cutting position.
So which type of machining should you choose for your project. It all comes down to your unique requirements, budget and timeline. For expert advice, talk with one of our professional precision engineers to find the right match for your needs.