Precision in motion

In recent years, Porsche Werkzeugbau GmbH, has elevated its mechanical machining capabilities to world-class standards, likening their day-to-day operations to “playing in the champions’ league.” This leap forward is largely due to the integration of two advanced Starrag Droop+Rein FOGS high-speed cutting (HSC) machining centers. These precision machines are primarily used to finish press tools designed for moulding the skin parts of vehicle bodies, an intricate process that demands extreme accuracy. The Starrag HSC machines excel at delivering exceptional surface quality, akin to a grinding finish, ensuring that the final products meet Porsche’s rigorous standards.

A premium car manufacturer should have a premium engineering plant. To ensure that the Porsche Werkzeugbau GmbH Schwarzenberg plant fulfils all of the preconditions for this, €40million was 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 25,000kN servo press for production-related tool try-outs and invest in retrofitting and new machine tools – including two Starrag HSC centres of the Droop+Rein FOGS 35 68 N40C type. In addition to this, mechanical production was completely overhauled and the production processes were restructured.

Engineering precisely what you value

Choosing Starrag machines was about more than just technical data. As Lutz Kramer, Head of Tool and Mold Making, notes: “We sought a comprehensive solution for our tool manufacturing, not just a machine. Starrag’s Droop+Rein specialists immediately understood our needs and aimed to leverage their expertise to help us.”

After installation, Starrag and our team worked together to optimize the workflow, integrating CAM, control systems, and the machines. This was crucial for achieving top surface quality and accuracy at high feed speeds, with careful attention to CAM-NC interfaces and control system adjustments.

This collaborative and precise approach, combined with the FOGS series machine technology, delivered excellent results. We achieved class-A surface quality and high accuracy at speeds up to 16m/min. “Stabilizing processes for aluminum forming tools took time, but Starrag’s support ensured success,” says Lutz Kramer.

A Solid Foundation for Innovation
Before implementing improvements, the entire tool-engineering team thoroughly analyzed the process chain, from development and design to procurement, production, try-outs, and transfer to the operator’s pressing plant. This review, including a fitness test for the machine pool, revealed room for improvement in tool finishing, particularly in accuracy, speed, and surface quality.

Lightweight Construction Challenges
Marco Franz, Head of Mechanical Production, explains: “The shift towards lightweight construction, especially in the Porsche competence center for forming technology, tasked us with developing tools for converting to an aluminum body. Aluminum responds more sensitively than steel during forming, creating challenges for tool engineering. Our existing machines couldn’t meet all the requirements.” To address this, two new high-speed machining centers were introduced to meet the demands for surface quality, accuracy, and speed.

Franz adds that these machines should improve efficiency, economy, and quality. Key requirements included process stability, availability, ease of maintenance, and temperature stability. Future-proof spindle performance was also crucial. Lutz Kramer notes, “When purchasing such machines, we expect them to last 10 to 20 years, during which several generations of more efficient milling tools will be developed. This must be factored in early.”

Raising the Bar for Machine Selection
Porsche Werkzeugbau’s decision-makers set high standards, which few manufacturers could meet. “In technical discussions, it became clear who could overcome the challenges. Some providers withdrew early, while others failed to offer viable solutions,” says Kramer.

Ultimately, they chose two Starrag Droop+Rein FOGS 35 68 N40C high-speed machining centers. These 5-axis machines, with an overhead gantry and traverse paths of 6.8 x 3.5 x 1.5m (X, Y, Z), are equipped with a tool magazine holding 100 positions, capable of using HSK32, HSK63, and SK50 retainers. Each features a 40kW milling spindle with 700Nm torque and spindles running at 18,000, 40,000, and 65,000rpm. Additionally, one machine includes a special 6,000rpm angular head for hard-to-reach areas. “With this spindle range, we’re prepared for the future,” says Kramer confidently.

Marco Franz adds: “Starrag met over 90% of our requirements, making the investment in Droop+Rein FOGS machines a great decision. We are now faster, more precise, and achieve exceptional surface accuracy.”

The head of tool and mold-making concludes: “We’re proud of our achievements with Starrag. The Droop+Rein FOGS machines improved quality and reduced manual bench work by about 20%, establishing us as leaders in large-tool engineering.”