More than 500 innovative machining solutions with 5-axis, 6-side milling and turning from barstock or the chuck have been implemented by the company for its customers. New, high performance materials, more complex machining processes and the trend towards more power density mean a demand for increasingly stable and flexibly configurable machine concepts.

STAMA’s new MT 733 series responds to demands for the highest possible dynamics, stability and precision – a technology trendsetter in the truest sense. The switch to a more stable fixed gantry concept – with much shorter levers compared to a traveling column – as well as vertical milling spindles is a decisive innovation leading to significantly better milling performance from the installation space. STAMA swivels the short bars via the B axis of the milling spindles – for example, in order to drill inclined holes or for simultaneous 5-axis machining – and the design of this axis was therefore crucial.

This extraordinary performance has been confirmed in numerous industrial applications – including STAMA: the zero backlash, extreme torsional rigidity and high repeat accuracy ensure precise positioning of workpieces swiveled via the B axis during machining processes. The high power density is no less impressive: owing to the compact design, access to the work space is easier and the turning spindles seated on the X slide can move even closer together. The advantage: no matter how short the components, they can be transferred reliably and accurately from clamping position 1 to 2 in order to machine sides 2 to 6. 
The specific machine control algorithms developed by STAMA and WITTENSTEIN together with Siemens for integration on the control side were adapted to the Galaxie^® Drive System’s mechanical behavior and integrated into the Siemens Solution Line control world.

The sphere test provides an apt illustration here. The machine did not simply make the sphere by moving in the X and Z directions; it also changed the gearbox direction via the B axis, which interpolates beyond the zero point of the Galaxie^® Drive System. Even minimal backlash in the drive would have sufficed to produce a measurable – and clearly visible – machining error on the sphere. Galaxie^®’s stiffness and freedom from backlash, coupled with the optimized control algorithms, are particularly evident when the contour accuracy and surface roughnesses are compared with the results of classic machining processes, which interpolate via two axes.

Extensive tests at STAMA have shown that significant wear on the Galaxie^® Drive System and positioning errors can be ruled out during the MT 733’s normal useful life. This information is based on endurance tests conducted in-house, in which the drive system was swiveled approximately four million times by ± 30° about the horizontal axis with the maximum static moment. The system was checked for changes every 500,000 cycles. Only a barely measurable change in the hysteresis loop was determined; there was no change in the freedom from backlash – not even at the zero crossing – and no sign of wear.

Complex components were completely machined in a single setup from blank to finished part. Manufacturing precision – expressed in manufacturing tolerances and baseline dimensions – was reproducible to less than one hundredth of a millimeter. The main time was reduced by 40 percent thanks to complete machining. All of the hoped-for improvements simultaneously materialized: shorter throughput times, lower internal transport and storage costs, simplified setting-up and alignment, reduced stocks of semifinished products and above all greater process reliability.

STAMA uses the CHIRON Group’s Smartline software portfolio to carry out digital analyses of operating states and processes – for instance, ConditionLine for monitoring the linear axes. Lifelong monitoring of parameters like friction behavior, backlash or hysteresis in the drive and the axis is possible in this way. These capabilities are analyzed and implemented in the framework of the long-term cooperation between STAMA and WITTENSTEIN. Owing to the analysis options, STAMA can offer its customers even more reliability in the future and help them exploit the full machining potential of the MT 733. And WITTENSTEIN can learn even more about Galaxie^®’s behavior in high-end machine concepts.