Application workpiece clamping technology at Koenig & Bauer

With innovation and discipline, those responsible for large-parts processing at Koenig & Bauer Industrial have been able to concentrate competence in Würzburg and prevent it from moving to Eastern Europe. The strategic investments in Würzburg are bearing fruit and are pulverising the earlier manufacturing times. The individual clamping solutions from AMF are playing a decisive role here. The core components of the sheet-fed offset presses are made flexibly and with process reliability using much fewer clamping operations today than in the past. Where once eleven clamping operations were needed, today only three are sufficient.

“From 2015 to 2018, we almost completely reworked production of the frames for the sheet-fed offset presses,” reports Jürgen Wiegand from Koenig & Bauer Industrial in Würzburg. “With new machines, automation, and intelligent workpiece clamping technology, we reduced production times drastically, considerably improved productivity, and so kept the competence and jobs in Würzburg,” says the supervisor of large-parts manufacturing at the world’s oldest printing press manufacturer. “We’re not only faster, but also more flexible,” the responsible programmer, Klaus Künzig, adds. Contributing to the speed and flexibility, besides the DMG machines, is especially the clamping technology from Andreas Maier GmbH & Co. KG of Fellbach (AMF). Among other things, the experts for clamping technology have equipped six pallets on two processing centres with clamping plates. What at first sounds commonplace and unspectacular is extremely challenging in detail. We’ll discuss that in more detail later.

A fraction of a hair’s breadth would be much too imprecise

How often has the printing press industry avoided collapse by a hair’s breadth? But it holds its ground again and again. Printing lives. Ultimately, not only money and securities have to be printed, but also packaging  - and also technical journals and the many advertising messages that we fetch daily from our mailboxes. All this requires sheet-fed offset presses, ideally from Koenig & Bauer - with over 200 years of experience, one of the first places to go. And even if we toss aside many printed messages without thinking, their production is a technological wonder. Printing press manufacturing is universally considered a supreme achievement and also a speciality of German machine building - even today. Despite the Internet and digitalisation. 

“For what we produce mechanically, a hair’s breadth would be much too thick,”  says Wiegand. For production of the core components, the boxes, as the frames are called internally, which hold the pressure 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, tolerances are only ten micrometres (10 µm). One of our hairs is seven times thicker. Complete frames or their side parts, made of grey cast iron GG25 from the company’s own foundry, require a dimensional accuracy and fit accuracy for parallelism and hole patterns that can hardly be imagined with such large parts. The connection surfaces must fit exactly. Only then can the pressure cylinders for the four base colours, multiple special colours and lacquers create the desired print image exactly.

Manufacturing of large parts is concentrated in Würzburg

In 2015, when the manufacturing of large parts were pulled together from Radebeul and from Austria in the newly established Koenig & Bauer Industrial in Würzburg, a DMC 210 from Austria also came to the city on the Main River – and AMF came into play. To enable setup on a total of three pallets during production, the clamping experts from Fellbach produced modular clamping fixtures and used their extensive standard portfolio for the hydraulic clamping elements and the zero-point clamping technology. As the machine does not have its own clamping hydraulics, AMF also contributes the hydraulic unit from its extensive product portfolio.

The AMF solutions quickly convinced the responsible people at Koenig & Bauer, so additional machines and processing stations were converted. “With these clamping and fixture solutions, we quickly brought the machine to its performance and capacity limit, so now we are planning for a new machine,” says Wiegand about the first project in the cooperation between the two companies. “This first project must certainly be seen as a chance to get to know each other,” confirms Erik Laubengeiger, Domestic Sales Manager at AMF. “And since we’ve convinced them here, additional projects will follow.”

Successful first project promotes mutual trust

A DMC 340 U of the gantry series, including 5-fold pallet changer, is equipped with AMF clamping solutions that minimise set-up time. That includes flexible clamping devices for four variants of components that are clamped and processed in pairs. “Those are the side walls for the shelf on which the paper sheets are stacked at the end of each machine or of the printing process,” Wiegand explains. 

A combination of hydraulic pull-down clamps and floating support elements fix the castings in the first and second clamping to ensure perfect evenness of the parts. Now the casting skin is removed, the contour roughened, and holes and threads are made. “These include the holes for the zero-point clamping bolts that are needed for the third clamping, the direct workpiece clamping,” says Laubengeiger. After release of the components, the processed castings are unclamped before they are turned. Turned by 180°, the zero-point clamping modules now receive the screwed-in pull-studs and fix the components directly, without distortion, and accessible everywhere for five-sided processing. To expand the capacity of the pallet changer and maximise flexibility, the machine pallets have AMF zero-point clamping stations, which permit fast and precise fixture change.

Reducing complexity with set-up and clamping plans

But the highlight is the flexibility of the clamping devices. Two movable support plates are mounted on a base plate. Hydraulic support elements, which are easily disconnected, can easily be moved. So the fixtures can not only seat two side parts, belong together as pairs, which can be processed on five sides after turning. All four variants of the components can be clamped in the respective processing conditions. To ensure that the workers keep an overview despite this unimaginable complexity, the correct positions for the respective component are colour-coded. “That gives us the necessary security and ensures speed during advance set-up while production is ongoing,” says Wiegand. For each component, there is both a clamping plan and a set-up plan, which are available at the machine.

Since the zero-point clamping technology from AMF has proven itself with its enormous time savings, subsequent processes, such as manual deburring, are also equipped with zero-point clamping modules. A correspondingly equipped scissors lift receives the components quickly and securely with direct clamping and permits ergonomic working. To summarise, intelligent clamping solutions from AMF have contributed considerably to economical production of the large frame parts and assisted precision.

Climate change in the finishing area

These processed components finally reach finishing in a climate-controlled area. There, they adapt to the constant 22° Celsius for 
24 hours before final processing on a high-precision Dixi 270 U and calibration on a Zeiss gantry measuring machine. “Each part, one hundred percent,” Wiegand emphasises. After that, they go to Radebeul for assembly. With courage and tenacity, the responsible people at Koenig & Bauer Industrial have shown that innovation and discipline, together with intelligent clamping technology, can pay off. And so know-how, competence and jobs stay in Würzburg.