Absolute zero-backlash, maximum rigidity, optimum synchronization properties and the large hollow shaft for the tool drive result in a highly torsionally rigid and thus, extremely precise gearbox solution in the upper turret. This means it is now possible to position the upper turret steplessly with high precision and to machine workpieces interpolating in several axes. This was not previously possible with a Hirth coupling and hydraulic clamping. Both components have been eliminated completely in the new turning machine – the solution with Galaxie^® allows the new INDEX ABC to machine a significantly wider range of parts.

The innovative Galaxie^® high-performance gearbox perfectly meets the requirements of precision machine builders like INDEX. The key characteristics – dynamic individual teeth instead of a rigid toothed wheel, full-surface contact during tooth meshing instead of a much smaller line contact, and the bearing design with segmented outer ring – make it far superior to cycloidal gearboxes and other gearbox technologies in all important technical parameters. The very high rigidity is constant even under alternating loads at zero crossing, without reducing the maximum transferable torques. In addition, the hydrodynamic lubrication means that disadvantages such as mechanical abrasion and wear are almost negligible with Galaxie^® gearboxes – in contrast to involute and cycloidal gearboxes.

The main challenges were the repeatability of the tool positioning and the rigidity of the overall system. After trials with various Galaxie^® gearboxes, the use of the Galaxie^® GS 190 from the new accuracy line with optimized, integrated bearing concept finally led to the goal. The integrated bearing ultimately produced the best possible rest values, which was an important acceptance criterion. In this regard, WITTENSTEIN also benefited from the close cooperation with INDEX: it was possible to successfully adapt the rest measurements, as used by the machine manufacturer, in the WITTENSTEIN test lab. As a result, WITTENSTEIN is now in a position to measure valid rest values of precision gearboxes and also transfer them to the digital twin.

The new turret technology offers end customers improved cycle times and higher productivity. The gearbox enables infinitely variable and highly precise positioning of the upper turret – with extensive improvements in the functionality of the CNC turning machine. It is now possible to realize an interpolated Y-axis, which enables the ABC turret to perform off-center drilling and surface milling, as well as a center height adjustment of the cutting edges. This ensures more precise machining of small bores, while the height correction allows the chip pattern to be improved. 

Many new additional functions
Another advantage results from the now possible use of double tool holders. With the same turret size and number of slots, this increases the tool capacity from 7 to 14 fixed or driven tools. This larger capacity can be used for sister tools or a larger machining spectrum. Another station is permanently occupied by the synchronous spindle for backworking. All these additional functions significantly increase the range of parts that can be machined on the new INDEX ABC. Due to the gearbox ratio and the function-related high efficiency of the Galaxie^® gearbox, INDEX was able to increase the energy efficiency of the turning machine. The use of the Galaxie^® gearbox opens up the possibility of a completely hydraulics-free machine in the future.

Another chapter has now been added with the Galaxie^® gearbox. The high-performance gearbox enabled significant improvements such as the continuously variable turret, its Y-functionality, the height adjustment and the switch to multiple holders. As a result, this small, extremely fast CNC turning machine meets current market trends toward smaller quantities and more complex geometries. The excellent price-performance ratio – to which the Galaxie^® technology makes a significant contribution – means that in the future, the INDEX ABC will also be usable for parts that previously required a more expensive machine.