With innovation and discipline, those responsible for machining large parts at Koenig & Bauer Industrial have succeeded in concentrating their expertise in Würzburg and preventing it from migrating to Eastern Europe. The strategic investments made in Würzburg are bearing fruit and pulverizing previous production times. AMF's individual clamping solutions play a decisive role in this. The centerpieces of sheet-fed offset presses are now manufactured flexibly and reliably in far fewer clamping operations than in the past. Where eleven clamping operations used to be sufficient, only three are needed today.

"Between 2015 and 2018, we practically completely overhauled the production of the frames for the sheetfed offset presses," reports Jürgen Wiegand from Koenig & Bauer Industrial in Würzburg. "With new machines, automation and intelligent workpiece clamping technology, we have drastically reduced production times, significantly improved productivity and thus kept expertise and jobs in Würzburg," says the foreman of the majority of production at the oldest printing press manufacturer in the world. "We are now not only faster, but also much more flexible," adds the programmer in charge, Klaus Künzig. In addition to the DMG machines, the clamping technology from Andreas Maier GmbH & Co. KG in Fellbach (AMF) also contributes to speed and flexibility. Among other things, the clamping technology experts have equipped six pallets on two machining centers with clamping plates. What sounds mundane and unspectacular at first is highly sophisticated in detail. Let's delve a little deeper into this.

With precision, a fraction of a hair's breadth would be far too imprecise

How many times has the printing press industry come within a hair's breadth of a crash? And time and again it has held its own. Because print is alive. After all, not only money and securities have to be printed, but also packaging - and not least trade journals and the many advertising messages that we take out of our letterboxes every day. All of this requires sheetfed offset presses, ideally from Koenig & Bauer - with over 200 years of experience one of the first ports of call worldwide. And even if we carelessly put some printed messages to one side, their production is still a marvel of technology. Printing press manufacturing is generally regarded as the supreme discipline and, on top of that, the showpiece discipline of German mechanical engineering - and still is. Despite the Internet and digitalization.

"For what we produce mechanically, a hair's breadth would be far too thick," Wiegand assures us. Tolerances of just ten micrometres (10 µm) apply to the production of the core pieces, the boxes, as the frames are called internally, which hold the impression cylinders, rollers and drums as well as the drives for the inking units, coating units, turning drums or other additional modules, such as for embossing. Our hair is seven times thicker. Complete frames or their side parts made of GG25 gray cast iron from our own foundry require a dimensional accuracy and accuracy of fit in terms of parallelism and drilling patterns that is unimaginable for such large parts. This is because the connecting surfaces must fit exactly. This is the only way that the printing cylinders for the four basic colors, numerous special colors and varnishes can later produce the desired print image with an exact fit.

Large parts production is concentrated in Würzburg

When the large parts production from Radebeul and Austria was brought together at the newly founded Koenig & Bauer Industrial in Würzburg in 2015, a DMC 210 from Austria also came to the Main - and AMF came into play. The Fellbach-based clamping experts produce modular clamping fixtures for set-up parallel to production on a total of three pallets and draw on their extensive standard portfolio for the hydraulic clamping elements and zero-point clamping technology. As the machine does not have its own clamping hydraulics, AMF also supplies the hydraulic unit from its extensive product portfolio.

The AMF solutions quickly convinced those responsible at Koenig & Bauer, so that further machines and processing stations were converted. "With these clamping and fixture solutions, we quickly pushed the machine to its performance and capacity limits, so that we are now planning a new machine," says Wiegand, summing up the first project of the collaboration. "This first project should certainly also be seen in terms of getting to know each other," confirms Erik Laubengeiger, AMF's Domestic Sales Manager. "And because we were so convincing here, further projects followed."

Successful initial project promotes mutual trust

For example, a DMC 340 U from the gantry series, including a 5-position plate changer, is equipped with set-up time-minimizing clamping solutions from AMF. This includes flexible clamping devices for four variants of components that are clamped and machined in pairs. "These are the side walls for the delivery, which stack the sheets of paper at the end of each machine or printing process," explains Wiegand.

A combination of hydraulic pull-down clamps and floating support elements fix the cast parts in the first and second set-up to ensure perfect flatness of the parts. The casting skin is then removed, the contour is pre-milled and holes and threads are drilled. "This also includes the holes for the zero-point clamping bolts, which are required for the third clamping operation, the direct clamping of the workpiece," says Laubengeiger. Once the components have been released before turning, the machined cast parts relax. Turned through 180°, the zero-point clamping modules now take up the screwed-in clamping bolts and fix the components directly, without distortion and accessible from all sides for five-sided machining. In order to expand the capacities of the plate changer and maximize flexibility, AMF zero-point clamping stations are located on machine pallets, which enable fast and precise fixture changes.

Reduce complexity with setup and clamping plans

The highlight, however, is the flexibility of the clamping fixtures. Two movable support plates are mounted on a base plate. Hydraulic support elements, which are only pinned, can be easily moved. This means that the fixtures can not only accommodate two side parts that belong together in pairs and can be processed on five sides after turning. All four variants of the components can also be clamped in the respective machining states. In order for the workers to maintain an overview of this unimaginable complexity, the appropriate positions for the respective component are color-coded. "This provides us with the necessary security and ensures speed during pre-setting parallel to production," assures Wiegand. There is also a clamping plan and a set-up plan for each component, which are available on the machine.

Because AMF's zero-point clamping technology in particular has proven its worth with its enormous time savings, downstream processes such as manual deburring are also equipped with zero-point clamping modules. An appropriately equipped scissor lift table picks up the components quickly and safely in direct clamping and enables ergonomic working. All in all, intelligent clamping solutions from AMF have contributed significantly to the economical production of the large frame parts and supported precision.

Climate change in the finishing sector

Components processed in this way are then sent to an air-conditioned area for finishing. There they adapt to the constant 22° Celsius for 24 hours before being finished on a high-precision Dixi 270 U and measured on a Zeiss portal measuring machine. "Every part, one hundred percent," emphasizes Wiegand. Then it's off to assembly in Radebeul. With courage and perseverance, those responsible at Koenig & Bauer Industrial have shown that innovation and discipline can pay off together with intelligent clamping technology. In this way, know-how, competence and jobs remain in Würzburg.