Supreme in precision and peripherals

Rauh + Kettner GmbH - Suitable tool changers, fixtures and improvised automation for milling were already available. But when the company Rauh + Kettner, in the Franconian town of Zirndorf, was due to invest in a new milling machine, they decided to take a big step in terms of automation. In 2019, the company decided to purchase the VERSA 825 machining center from Fehlmann, including an Erowa Easy 250 robot. The machine cell has now been able to convince the decision-makers, thanks to achieving the desired output and contributing significantly to cost savings with its high level of precision

Orders at Rauh + Kettner were good and continue to be so. However, in spite of partial automation, by the end of 2018 the milling of inserts and mold plates was still too labor-intensive for Managing Directors Armin Arnold and Daniel Pfaffinger. So the objective was clearly defined: they wanted to invest in a machining center that would meet the high demands regarding precision. On the other hand, they wanted to become even more competitive with an all-round machine in continuous operation, with the corresponding level of automation. They, therefore, went about gathering information on the VERSA 825 machining center, made reference visits to well-known companies and also went on site to Fehlmann in Switzerland. For Daniel Pfaffinger, this visit to Switzerland was an absolute seal of approval for the precision they required: "What impressed me here was the enormous degree of vertical integration, because this is the only way to ensure that the machines also deliver the corresponding precision and reliability. Dimensional accuracy and high surface quality are extremely important to us, because we mill mirrors, for example, which are then polished. At the moment we are working on a shape that resembles a cylinder. With a 12 mm spherical cutter, the VERSA 825 can achieve a surface finish to within 2 µm. What is particularly pleasing in this context is the fact that we now achieve time savings of between 35 and 40 percent for polishing”. When it comes to the specifications for molds for eyeglass lenses, they are also operating at their limits, because such lenses must have zero tripodia. However, the precision of the VERSA 825 is only one factor that contributes to the desired results. For those responsible, it was also the peripherals that Fehlmann mastered with aplomb. This starts with the team in Zirndorf working with clamping systems, pallets and chucks from Partool. And as already mentioned, the robot is from Erowa. Yet the compatibility of these individual components has never been a problem.

You would have to search for a long time to find anything comparable
Fehlmann sees the VERSA 825 as a 5-axis machining center designed both for dynamic HSC milling, as well as for machining difficult-to-machine materials. In addition, Fehlmann promises that its automation solutions can be seamlessly integrated at any time. Such automation was a top priority for Rauh + Kettner. This is also one of the reasons why the VERSA 825's tool changer has 218 pockets and the robot has a changer for 10 pallets. According to Armin Arnold, Fehlmann had clear advantages over comparable machines here: "The accessibility of the machine is fantastic and in spite of the automation and tool changer, the machine cell is absolutely compact. The variety of set-up options is also enormous. You would have to search for a long time to find anything comparable. Irrespective of this, quality is always the main focus of our investments. Our Versa 825 runs around the clock. On Wednesday it is switched on and runs through to Tuesday. We expect that to continue to be the case reliably for many years to come. Another positive experience we had is that we assumed a lead time of two to three months. Yet we were able to mill highly complex operations with this machine after only three weeks.”

In Zirndorf they now have access to a number of options with the Versa 825. These include 3D measuring probes, automatic kinematic measurement, the MCMTM (Milling Center Manager) and length compensation, as well as programming cycles. According to Daniel Pfaffinger, the Milling Center Manager is made by practitioners for practitioners. According to him, the job manager is very simple to use, not requiring much training and offering excellent efficiency. The length compensation feature makes sense for him because the temperatures at different speeds have to be compensated for. Daniel Pfaffinger estimates that the lack of compensation would certainly result in a much bigger offset. But even with tolerances of less than 1/100 mm there are no dimensional problems in Zirndorf anyway.

The programming cycles, on the other hand, are settings based on parameters stored by Heidenhain and defined by Fehlmann for practical use. In detail, this means that the movement in the X, Y and Z axes can be varied. In other words, a concrete distinction can be made between speed, precision or surfaces. Another feature is the weight cycle (workpiece). Depending on the weight of the tool on the swiveling bridge, a recommended traversing movement can be set.

Be it combining mold plates, inserts, embossing stamps or even tungsten-copper electrodes, the machine cell concept in Zirndorf is convincing. And the absolute added value for those responsible: The precision amounts to considerable time and cost savings, as the time taken for the polishing process was also able be drastically reduced.

Rauh + Kettner’s precision mold and tool making
The company was founded over 30 years ago in Zirndorf. It has now established itself as a tool and mold maker for suppliers in the automotive, occupational safety and fiber optic, medical technology and toy sectors. Its product portfolio includes complex and high-quality molded parts as well as injection molding tools made of up to four components. In order to meet the current state of quality criteria and actively participate in the change process, Rauh + Kettner has implemented a quality management system in compliance with ISO 9001.

By the way
The situation, clamping systems from Partool and automation/robots from Erowa, was a particular challenge, but Fehlmann was able to meet it quickly and without any problems.

Rauh + Kettner GmbH
Mr. Armin Arnold
D-90513 Zirndorf
Tel. + 49 911/600-3995


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