The Kempten-based company has been one of the leading manufacturers of gear cutting machines and automation systems for seven decades. However, the increasing individualization of machines, ever smaller batch sizes and the shortest possible throughput times have presented Liebherr with major challenges. Under the premise of process reliability, the Kempten-based company therefore implemented consistent digitalization and automation. The Allgäu-based company has been supplying turnkey production cells and lines since the 1970s. The company's own production is also highly automated, clearly demonstrating that "flexibility and automation go hand in hand at Liebherr," emphasizes Matthias Dodel, CAM programmer and system supervisor for production lines at Liebherr. As small series up to batch size 1 with a large variance of parts are manufactured in Kempten, automation is carried out using a Liebherr pallet handling system, among other things.

The component to be processed is clamped onto a uniform carrier plate by an operator outside the machine and then temporarily stored in the integrated high-bay warehouse until processing. When the host computer gives the order for processing, the carrier plate with the component is transferred to the processing center by the rack vehicle and then picked up again. All travel and storage/retrieval movements are carried out automatically without human intervention.

Production control

The Soflex PCS (Production Control Software) software ensures long tool life, despite the high degree of individualization of the workpieces. It controls the entire production process and plans the entire sequence on the basis of the ERP system data. In conjunction with the TDM tool management system, this enables "highly flexible, reliable and efficient production around the clock," emphasizes Dodel.

With the decision for an automated milling and turning center, the systems involved were also put to the test and the entire process chain was reconsidered. In particular, the tool management system previously used was no longer suitable for the new challenges: "It was a proprietary stand-alone solution that was tailored to our previous CAM software and therefore not compatible with the new solution." Adapting it accordingly would have been very time-consuming and costly, and it would have been almost impossible to implement a continuous process chain across the entire production process. "Because the interfaces were missing, the continued use of the software would have become a constant challenge for us," says Dodel.

From the outset, Liebherr was therefore looking for a solution partner "for whom there are no technical limits in the interfaces to all possible applications in production". And because, according to Dodel, they repeatedly encountered satisfied TDM users during their reference visits to numerous CAM manufacturers and also within the Liebherr Group, Liebherr opted for the tool management solution from TDM Systems in 2018.

"TDM is a software that offers us all the freedom we need thanks to its variety of interfaces and enables us to implement our digitalization concept efficiently," says Dodel, summarizing the management decision. This decision also secures Liebherr's investments in the long term - because the neutrality and openness of the TDM system means that they are not tied to specific software providers in production.

The implementation of the software was problem-free and the data transfer also ran as desired right from the start. It quickly became clear: "The elimination of manual data entry reduced the error rate to zero," says Dodel. Liebherr uses TDM not only for traditional tool management, but also as a document management system for CAM documents, NC programs and set-up instructions. All tool and fixture requirements of the machining centers are handled by the storage and fixture management system. The interfaces to the Esprit CAM system, Soflex production control system and Zoller presetting system enable automated data flow. Also interesting: The service department uses the automated warehouse connection from TDM to manage the fitters' equipment.

Direct data access saves time

For small series up to batch size 1, NC programming quickly becomes a bottleneck in production. According to Dodel, those who cannot or do not want to hire additional employees are dependent on optimizing their processes. Liebherr has succeeded in doing just that. They created around 5,000 NC programs with the same team within four years - despite expanding their machine park. "It would have taken us ten years in the past," says Dodel, pleased with the extensive time savings. At the same time, this team digitized the tool inventory, i.e. set up the entire tool database and also took over further data maintenance.

The fact that the NC programmers are so efficient thanks to TDM is due to the modules for data and graphics generation, as well as the CAM interface from TDM-Esprit. This is because the permanently defined complete tools are consistent and can therefore also be used as digital twins for simulation. This also completely eliminates the need for manual data input during programming.

Complete tools always available

Tool management at Liebherr revolves around complete tools: 3,800 complete tools and 7,000 fixtures are managed at Liebherr. When the production control system plans an order, the complete tools required for it are determined and the requirement is compared with the tools available on the machines or with the respective tool life. If tools are missing, they are assembled, preset and measured using a requirements list from Soflex. The presetting also works with data from TDM and automatically accesses the created target data.

This means that only data is transferred, no longer entered. Tool changes are carried out fully automatically when required or when the tool life expires, without human intervention. "Without TDM, it would not be possible to keep track of 3,800 complete tools and deliver them to the machine at the right time and in consistent quality," emphasizes Dodel. "Without the software, tool supply would simply not be possible and automation would not be possible."

"In summary, it must be said that we always work with process-reliable data thanks to the automated data transfer from and to the TDM software," emphasizes Dodel. At Liebherr, TDM tool management plays a significant role in ensuring that the systems and processes are interlinked, that data flows and that processes interlock automatically. And to become even more efficient in the future, Liebherr Verzahntechnik is striving to reduce the variety of processes and tools by standardizing the technological guidelines. According to Dodel, "TDM will also provide us with strong support".