The supreme discipline in measurement technology

Wolfsburg - In order to constantly improve quality, productivity and process efficiency, it must be ensured right from the development phase that every Volkswagen Group automobile is measurable. This applies to the entire range of brands and variants, from roof to floor assembly. With the RAX horizontal alarm measuring devices Volkswagen has implemented the right solution from WENZEL. There are now 5 duplex systems in use.

Quality assurance at the pre-series center in Wolfsburg is the supreme discipline of measurement technology. New trends in measurement technology are being set on test vehicles. Developers are first confronted with novel measurement tasks here. The manageability of these measurement tasks may have an impact on the product development process.

“In product development, we must define as early as possible which requirements and quality criteria must be taken into account,” explains Stefan Eckhardt, QA Pre-Series Center Department, Analysis Center. His superior Frank Eggeling adds: “We cover the entire spectrum of Volkswagen. A large measurement range was therefore very important for us so that, for example, a VW bus could also be measured with high accuracy. ”

Recipe for success: Close collaboration

“Of course, measurements were carried out with relatively large coordinate measuring machines even before the introduction of our measurement solution,” describes Thomas Werner, Head of Technical Sales at WENZEL. “But the mechanics used were getting old and the control technology, software and probes were no longer technologically up to date.” Volkswagen's considerations ranged from comprehensive modernization to new purchases. It was important that the new solution was sustainable, i.e. that it met the requirements for at least 10 years.

After an intensive in-house selection process, Volkswagen opted for a completely new development from WENZEL. The decision for RAX horizontal arm measuring devices was a great sign of confidence in WENZEL's innovative expertise. The project was carried out from start to finish in close coordination with Volkswagen. “The requirements were very high. But working with measurement technicians, who have many years of experience, was a great asset for us,” explains Thomas Werner.

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The result is the RAX, the latest CNC horizontal alarm measuring device from WENZEL's proven R-series. WENZEL is proud that the RAX was more accurate than required and, despite the high Z range, measures more precisely than comparable smaller measuring devices. The limit value for the length measurement deviation MPEE was specified as 40 + L/40 μm. The coordinate measuring machine is suitable for the use of switching, scanning and optical measurement systems.

The measuring devices were equipped with the continuously adjustable motorised PHS rotary and swivel head from Renishaw. The PHS was developed to meet the high requirements for measuring car bodies in the automotive industry. It increases the functionality of the machine, particularly where fine angle positioning and a long probe length are required.

Even the standard version of the RAX offers a very large measurement range of 3,100 mm in the Z-axis. Depending on the probe system, the measurement range in Z starts at 70 mm above the base plate.

This means that the measuring arm can be driven under the vehicle at road level. Due to the mirror-image design of the duplex version, the measurement range in the X-axis is optimally utilized. At Volkswagen, the X-axis is 6,000 mm, as the foundation pits of the old plants were used. If necessary, significantly longer multi-column systems can also be built.

Perfect accessibility for all measurement and maintenance tasks

The RAX is equipped with highly accurate linear guides in all axes. These ensure optimum durability and stiffness. The X-axis guide is integrated into the base plate at ground level and covered so that it can be traveled on. This design allows vehicles to be driven onto the RAX despite the limited space of the measurement room. The measuring device is perfectly accessible from all sides, both for measurement and maintenance tasks. All relevant components can be removed and reattached in just a few simple steps. This reduces maintenance times and increases the availability of coordinate measuring machines.

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The RAX systems are equipped with active temperature compensation. This ensures that accurate measurement results are obtained despite any deviating temperatures. The workpiece temperature sensors are installed wirelessly. The existing foundations could be reused. These are equipped with damping devices so that the influence of vibrations on the measurement result is minimized.

Monitoring access to the measuring machine using light barriers enables the high machine speeds to be fully driven. The mirror pillars of the light barriers can be easily removed to drive in a vehicle and reproducibly reused without adjustment.

Diverse areas of application

With RAX measurement systems at VW, everything that the automotive sector has to offer is measured. Complete vehicles, bodies and individual body parts. In addition, RAX can be used in many other industries. It measures, for example, large-volume machine components, trucks, agricultural and construction machinery, but also workpieces from the aerospace and energy sectors.

“We have now been working with RAX measuring devices for two years and are very satisfied with them,” explains Hans-Jürgen Bach, head of the QA pre-series center at Volkswagen AG in Wolfsburg. “It was also important for us that we get the complete service portfolio from a single source.” Stefan Eckhardt adds: “With this solution, we are well positioned for the future. Thanks to continuous development at WENZEL, we are able to upgrade to the latest technology at any time. ”

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