No Room For Environmental Temperature Fluctuations

Galaxie® by WITTENSTEIN is a true innovation in gearbox kinematics: dynamic single teeth instead of gear teeth, surface instead of linear contact and an interlocking system with a logarithmic spiral. To ensure that everything fits together perfectly, all gearbox components must be manufactured with high precision. Marco Gravera, Head of Quality Assurance, relies on a ZEISS PRISMO ultra for this reason. He controls environmental conditions with ZEISS TEMPAR.

Galaxie® by WITTENSTEIN: an innovative gearbox generation with 48 dynamic single teeth

Employees at WITTENSTEIN, a manufacturer of electromechanical drive systems quickly determined that by looking at familiar designs, there was no possibility of launching a real revolution in terms of gearboxes. So engineers tried something new and left the usual patterns of thought behind—with success. The result: the very first gearbox without gear teeth, named Galaxie®. Galaxie is a gearbox generation that has completely revolutioned the gearbox principle once again. Instead of gears, Galaxie consists of 48 individual dynamic teeth. The teeth take on the shape of a logarithmic spiral—similar to a galaxy. Just like a linear contact is used for torque transmission in planetary gears, Galaxie produces an almost complete surface contact. The advantage: much higher torques. All this results in a gearbox which is completely free from backlash and with high rigidity—making it much more powerful than other types of gearboxes and perfectly suited for high-performance mechanical engineering. For its innovative technology, the gearbox was also awarded the so-called Oscar for engineers, the HERMES AWARD 2015.

Production Island Improves Processes

WITTENSTEIN has established an internal start-up to promote the advancement, production and marketing of Galaxie. Peter Lesch, Head of Production & Logistics for the start-up, has been a WITTENSTEIN employee for 29 years: “We have set up completely new production processes at Galaxie. In order to master these successfully, we are currently setting up our own production island. In addition to production, we integrated assembly, an internal test bench and quality assurance.” The other start-up departments such as logistics, development and sales are also directly connected to the production island. Marco Gravera, Head of Quality Assurance, sees a decisive advantage in physical proximity: “This makes all employees feel like a single unit. This leads to an improved and faster cooperation—above all, between the employees engaged in quality and production. This enables us to adapt our measuring processes much more quickly to the production processes and their development.” The interaction between the two departments is indispensable for the production of the new gearbox generation. Some of the manufacturing technologies are also breaking new ground for WITTENSTEIN; however, thanks to the short feedback loops with quality assurance, these can “be mastered much more quickly”, according to Lesch.

Perfect Conditions For Maximum Precision

ZEISS TEMPAR sensors measure the temperature in the measuring room

Gravera and his team measure the core components of the gearbox during production: at the end of this process, 100% of the gearbox is measured at the test bench. Supplier components are likewise submitted for an acceptance check in the measuring room first. Because when the 48 round teeth slide through the tooth carrier, the highest precision, in the range of a thousandth millimeter, is required. And not only there: to ensure that everything interlocks perfectly, all gearbox components must be manufactured with high precision. To meet these precision requirements, Gravera’s team uses ZEISS PRISMO ultra and a SURFCOM NEX for measurements. The coordinate measuring machine (CMM) has a length measurement error of only 0.5 + L/500 micrometers. However, to deliver such precise measured values, the measuring device places high demands on the environmental conditions. Fluctuating temperatures cause materials to expand or contract. The more precise a measuring instrument is, the more temperature fluctuations need to be taken into account. The measurement reference temperature for a ZEISS PRISMO ultra must be kept within a range of 20 – 22 °C, while errors per hour or meter are only permissible within the range of 0.5 °C.

Environmental Temperature Under Control

Gravera therefore knew from the very outset that the new measuring room would have to be equipped with a temperature monitoring system. With TEMPAR from ZEISS, Gravera found a system that could do much more than just measuring the temperature. “It was very important for me to have a system that measures the temperature 24/7, monitors it and, above all, records it in a traceable manner.” Nine sensors are evenly distributed around the coordinate measuring machine and record even the smallest temperature fluctuations. Gravera can always visualize all the values on one console, including the measuring room class according to German standards VDI/VDE 2627. “Our goal is to ensure that the measuring room always meets the requirements for quality class 2”, explains Gravera. “Even on my first metrology seminar, the lecturer already told us that temperature has the greatest influence on the measurement result. That’s why it’s very important for me at a personal level that we absolutely master this parameter.”

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