The name Grob stands internationally for machine tools of the highest precision. The family-owned company based in Mindelheim enjoys great trust in the automotive industry, in aircraft construction, in medical technology and in a number of other sectors. The product portfolio is divided into the areas of system machines, universal machines for machining, systems for electromobility, complete assembly systems consisting of modular machining centers and special machines, as well as the area of new technologies. Worldwide, the Grob Group generates a turnover of around 1.3 billion euros with almost 6,000 employees on four continents. "We place high demands on ourselves and aspire to be number 1. This requires constant technical innovation. We expect exactly the same from our suppliers," explains Anton Kuhn, Head of Fluid Design at Grob.

5-axis universal machines from Grob can be used in a wide variety of areas - such as mold and prototype construction with demanding, high-precision geometries with spatial bevels and spatial bores. The machine tools work to an accuracy of a thousandth of a millimeter. Such precise machining requires the workpieces to be positioned and fixed in complex clamping fixtures. Hydraulics play a particularly important role here. It has the task of clamping tools and balancing weights. It also ensures the clamping of axes and spindles. As a rule, up to 120 bar acts on the hydraulic connections, in some cases even up to 300 bar during pressure peaks. Around 70 to 100 m of hydraulic lines are installed in the G-series machine tools, in addition to countless connections. In accordance with the quality standards defined by Grob, the connecting elements between the individual hydraulic pipes must be extremely leak-proof. "The hydraulics are a sensitive component of our machine tools, as hydraulic drives ensure maximum precision during tool movements. The connection technology must therefore be reliable and permanently leak-free," emphasizes Kuhn. In addition to being leak-free, easy handling and an attractive price-performance ratio are further requirements that Grob places on its suppliers of hydraulic connections.

Grob mainly uses the VossForm SQR connection solution. In addition to the quality, the simple handling of this hydraulic connection was a decisive factor. Only a few work steps are required to create a secure connection: first, the VossForm 100 forming machine forms a 24° pipe contour on the end of a hydraulic pipe within a few seconds. To do this, the end of the pipe must be pushed into the machine up to the stop plate. As an internal mandrel at the end of the upsetting head prevents the pipe from being constricted, the internal pipe diameter is completely retained and pressure losses due to bulging are prevented. Together with a soft seal made of fluorocarbon rubber (FKM) and a specific SQR functional nut, a simple and high-quality connection is created. For Grob, the installation safety provided by the protection against over-assembly is a particularly decisive advantage of the system: during final assembly, the end face of the formed pipe end strikes against the base of the socket in the fitting body. When the functional nut is tightened, these components are firmly clamped together, with a noticeable increase in force signaling to the fitter that the end of assembly has been reached. "The majority of all leaks are caused by incorrect assembly. With VossForm SQR, we significantly reduce this risk. In our opinion, this technology is therefore the safest and best connection. Our employees are also satisfied with the system," says Kuhn. Grob has twelve VossForm 100 forming machines in use around the world.

Connection remains dry

In addition to tube forming with VossForm 100, the internationally active family business also uses the soft-sealing ES-4 cutting ring from Voss. Grob uses this in particular in its system machines for the automotive industry. The functional principle is based on a two-cutting edge technology with two additional soft seals. The two soft seals are a special feature of the ES-4: with the help of the completely gap-free chambered soft seal, the ES-4 guarantees a dry and sweat-free connection even if the metal seal should weaken. The connection can even withstand vibrations in this way. The gap-free chambering of the seal is achieved by the block assembly. This prevents the ring from cutting too deeply, thus preventing over-fitting.

What Grob appreciates about his partner Voss Fluid is not only the high quality of the products and their simple and safe handling, but also the service. "Voss Fluid is an agile company with a customer-oriented approach," describes Kuhn. In order to guarantee the required short response times, Voss Fluid and its sales and service partner, Fritz Stiefel GmbH, keep some of the required material in stock. Grob not only benefits from high adherence to deadlines and delivery reliability, but also from product and installation training. Together with its sales and service partner, Voss Fluid regularly trains the machine manufacturer's fitters in the correct application. "We have been working with Voss and Stiefel for thirteen years. Since then, we have been very satisfied with the product quality and service we receive through this partnership. We hope that this will continue in the future," concludes Kuhn. cs