Workpiece clamping Highly automated small parts manufacturing

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As part of the reorganization of the entire production, Krones Nittenau has been heavily investing in its small parts manufacturing since 2021. Clamping systems from Gressel are used in the implementation of a highly automated manufacturing concept.

Krones, headquartered in Neutraubling (Germany), is considered the world market leader in the planning, development, and manufacturing of process, filling, and packaging technology as well as intralogistics. Worldwide, tens of millions of bottles, cans, and molded containers are processed daily with Krones systems, primarily in breweries, the soft drink industry, wine, sparkling wine, and spirits producers, but also in the chemical, pharmaceutical, and cosmetic industries.

Three-stage plan for large parts manufacturing

In Germany, Krones produces with about 9,000 employees at five locations. One of them is Nittenau in the Upper Palatinate, where large and small parts of machines and systems for the main plant are manufactured. To ensure long-term competitiveness, Nittenau invested in a modern large-scale machining center for turning and milling in 2021. This investment was part of a reorganization of the entire manufacturing area started in 2018, comprising three stages as an investment program. Krones Nittenau completed the first step of the program at the end of 2020 with the commissioning of a new laser welding system, which included optimizing upstream and downstream processes and restructuring the material flow. In the coming years, phase three will see the commissioning of additional turning and milling systems.

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Parallel to the program for large parts, Krones Nittenau also heavily invested in small parts manufacturing starting in 2021, where components between 5 and 1,250 millimeters (approx. between 0,2 and 0,05 in) in size are produced. These investments are associated with extensive automation and digitization measures aimed at ensuring the timely supply of high-quality parts in the future. As with the production of large parts, this occurs in small parts manufacturing in several steps. "We have devised a plan until 2028, which consists of several steps," outlines department head Vitali Schmidt of the scenario.

The implementation began with a highly automated manufacturing concept, whose essential components include milling machines, clamping tools, and driverless transport systems. The decision to choose clamping systems from Gressel is partly justified by the next step. Here we will move towards turning machining using the same clamping systems. In this respect, they are an investment with foresight.

Vitali Schmidt, Head of department, Krones Nittenau

Before modernization, the milling area at Krones Nittenau was operated in a traditional manner: "We pre-assembled on pallets, brought them to the machine, and lifted them in by crane," Schmidt explains. In the meantime, performance hours had been recorded and the number of hours increased with a separate setup station and optimized processes, but now the concept was maxed out. They were looking for a process with less setup at the machine and where employees were not tied up by the setup. This was only possible through automation. With this approach, a concept was developed with ten 5-axis machining centers G550 from Grob, a fleet of driverless transport systems (FTS) "Agilox" for handling workpieces and tools, as well as a whole series of clamping systems from Gressel.

As a result, we no longer have the classic operator at the machine today. There have also been drastic changes in work preparation. Today everything has to be 100 percent prepared. The programs must be 100 percent accurate, every screw, every vise has to be drawn in advance. This is a major challenge for the programmers.

Vitali Schmidt, Head of department, Krones Nittenau

Apart from the setup, Krones Nittenau primarily wanted to achieve two objectives with the transition. First of all, the machine runtime is to be significantly increased. "In the first step, an increase from 3,500 to 5,500 hours is planned," specifies the department head. "In the second step, we want to reach 6,000 hours, resulting in almost 40 percent more output and a substantial cost reduction to remain competitive internationally." The second point arises from employee turnover and a shortage of skilled workers. As in the old manufacturing world, Krones will also operate in three shifts in the new setup. "We might already run night shifts without personnel next year," Schmidt announces. "Initially, there will still be an employee on-site to re-clamp the parts, but a system operator will no longer be necessary. This way, we aim to reduce costs per hour—in addition to increasing the machine's output."

Orders are now started from a delivery point for sawn parts. A control system then checks whether all the required tools are in the machine. If this is not the case, the set is assembled. For example, from another machine that is not currently using the tool. An Agilox then transfers this tool to the first machine, as well as other tools from the central presetting. The remaining requirement had been automatically dispatched here beforehand. Once an FTS has picked up the preset tools and brought them to machine 1, the tool loading is complete.

The production itself operates under tool life monitoring, where the system also considers the remaining life of tools already in use. Depending on the processing time of an operation, the system automatically orders a duplicate tool to ensure the remaining work is completed. Again, it checks whether a tool can be transferred from another machine or if a new one is required from the tool presetting.

Vitali Schmidt, Head of department, Krones Nittenau

In a second loop, another Agilox fleet handles the workpieces. After being clamped at the setup station, an FTS brings the pallet to machine 1. "Here, it is placed in a buffer storage with nine slots and simultaneously integrated into the internal system," Schmidt explains. "The system then enables parts to be completed from the buffer based on different priorities according to delivery deadlines." After processing, the part goes into inspection. If everything is in order there, the system restarts and brings the pallet with the next part. How many parts are inspected in which cycle can be flexibly set. All parts feasible in terms of travel paths and clamping possibilities are manufactured in this way, whether they are made of aluminum, brass, or stainless steel. Batch sizes on the machines range from 1 to 50, often between 1 and 30. "We don't want to handle more than that, due to the throughput time," emphasizes the department head. "Since the number of different parts being processed is very high, easy and quick re-clamping is essential."

"The clamping tools we have deployed reflect this great variability," emphasizes Sokha Hem, sales technician at Gressel. "In addition to pyramids, C2 centric clamps, and Gredoc zero-point modules and plates, these include 5-axis clamps SC5X, S2 fixed jaw clamps, clamping towers, and D2 double clamp towers." The collaboration, especially the development of the clamping tasks, was extremely constructive and cooperative. The first effect Krones Nittenau achieves with the systems is the intended setup efficiency, which comes with features like quick jaw and spindle changes or rapid clamping range adjustment. "Added to this is the high stability of the clamping tools, which, together with the machine's stability, is indispensable for precision," says Hem. Schmidt explains the necessity:

A machine is only as good as its clamping system. But we manufacture many parts in the hundredth range. For this, the high stability and repeatability of the Gressel systems are just as necessary as the high retention forces that ensure secure fixation.

Vitali Schmidt, Head of departement, Krones Nittenau

A decisive factor for Krones is also the standardization that comes with the clamping tools. Nittenau has now defined the Gressel systems as the standard for milling. Turning is set to follow soon, which means that the zero-point clamping system will be used on all machines. In addition, the clamping tools are intended to be used for production in the main plant in Neutraubling in the future. "We want to be able to process parts manufactured there at the push of a button with us. However, that only works if the clamping tools are the same." Standardization is also crucial for international operations, such as in America, where it influences the spare parts business. By rolling out identical manufacturing tools internationally, parts can be easily produced abroad. Schmidt thus returns to the basic premise: "The entire concept is geared towards automation. This means the focus is on the seamless interaction of the individual, digitized components. Gressel's systems are a firm foundation for this."

*Michael Hobohm is a freelance author