We play in the champions’ league every day

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“We play in the champions’ league every day”

In recent years, Porsche Werkzeugbau GmbH in Schwarzenberg, Germany, has taken its mechanical machining to the highest technical level. Two large Starrag HSC machining centers Droop+Rein FOGS play a major part in this. These are used to finish pressing tools for molding skin parts of vehicle bodies with the utmost precision and produce surfaces with grinding quality.

A premium car manufacturer should have a premium tool-engineering plant. To ensure that the Porsche Werkzeugbau GmbH Schwarzenberg plant fulfils all of the preconditions for this, 40 million euro were invested over the last five years to develop the tool-engineering plant to the highest possible level following the transition from KUKA. Among other things, the Schwarzenberg-based company used this money to set up two new production halls, purchase a new 25,000-kN servo press for production-related tool tryout and invest in retrofitting and in new chip removal machine tools – including two Starrag HSC centers of the Droop+Rein FOGS 35 68 N40C type. In addition to this, mechanical production was completely overhauled and the production processes were restructured.

All of these measures were based on a solid foundation: Beforehand, the whole tool-engineering team analyzed the entire process chain, from development and design to procurement, production and tryout of the tools, right through to the transfer to the operator pressing plant – including a fitness test for the pool of machines. An important detail that came to light was the realization that when it came to mechanical machining, there was potential for improvement in the finishing of the tools, particularly in terms of accuracy, speed and surface quality.

More than a machine – Engineering precisely what you value

There were other reasons for choosing the Starrag machines, in addition to the technical data, as Head of Tool and Mold Making Kramer explains: “We didn’t just want to buy a machine, we wanted a solution for our tool manufacturing process. That is one of the main reasons why Starrag seemed to us to be the right partner. With the Droop+Rein specialists, we had the impression right from the start that they were listening to us, wanted to understand us and the thinking behind our processes, and wanted to use their expertise to help us”

Once the machines were installed, the two companies began fine-tuning the workflow together, taking into account the characteristics of CAM, the control system and the machine. This was necessary because achieving the best surface quality requires a high level of accuracy on the path, even at the highest feed speeds. For this, it was important to illuminate the interfaces between CAM and NC and to work with experts from the control system manufacturer to optimally adjust their functionalities in line with the process requirements.

This interdisciplinary approach and the combination of sophisticated drive optimisation in conjunction with the proven machine technology of the FOGS series was extremely successful: The result was not only a class-A surface but also a very high level of accuracy – at the highest path speeds of up to 630 ipm (16 m/min) on the free-form surface. The processes have been running stable ever since. Lutz Kramer is delighted: “It took a long time to achieve stable processes, especially when it came to the forming tools for aluminum parts, because there are many factors influencing this. But Starrag assisted us until we were sure we had reached our goal”. Marco Franz adds: “I wouldn’t have believed it at the start. But Starrag was actually able to implement more than 90% of our wish list. So it was definitely a good decision to invest in the new Droop+Rein FOGS machines. We are now faster and more precise and achieve – depending on the component and the geometry – outstanding surface accuracy”.