Unique high precision
Koenig & Bauer produces large components for printing presses with a high level of productivity and in the µm range with four DMC U machining centres and a DIXI 270 from DMG MORI
After inventing the first steam-driven cylinder printing press in London in 1814, Friedrich Koenig returned to Würzburg with Andreas Bauer in 1817 to found today's Koenig & Bauer AG. The company significantly influenced the production of printing presses with its experience and has lived up to its claim of being a leader of innovation in its markets right up to the present day. Apart from newspaper printing, these markets also include sheet-fed printing, packaging printing and metal-decorating printing. In addition, over 90 percent of the world currency is printed on machines from Würzburg. Since February 2015, Koenig & Bauer has been using a turnkey solution from DMG MORI in order to ensure the standard of quality in production for the machining of large volume parts. This configuration consists, among other things, of two prototypes from the machine tool manufacturer: a highly productive DMC 270 U including an RS 4 pallet pool and an ultra-high precision DIXI 270.
It was a milestone in the flourishing newspaper market in 19th century London when Friedrich Koenig’s steam-driven cylinder press printed the London daily newspaper “The Times” for the first time. In the years following, this Koenig & Bauer set a foundation for the entire printing press industry. Almost 200 years later the triumphant march of the Internet had an enormous impact especially on newspaper printing and this in turn led to great changes. “We moved into new markets in good time in order to retain our competitive edge”, says Ewald Baumeister, Head of the Frame Production Division at Koenig & Bauer, looking back at the developments that have taken place in recent years. With great success: the second largest printing press manufacturer according to turnover in the world is the global market and technology leader in the field of large format sheet-fed offset presses, packaging, newspaper and metal-decorating presses.
Success for Koenig & Bauer starts with its almost 6,000 employees worldwide, 1,600 of whom alone work at its location in Würzburg. The company has even established its own on-site vocational school – a private state-recognised school – in order ensure an up-and-coming generation of well-trained skilled workers. With a view to the modern production, this is an important step for Ewald Baumeister: “Machining of the components for our printing presses requires a high level of expertise.” Very low tolerances apply especially in mechanical production. “So the machining technicians working there must know exactly how to get the most out of the CNC machines.”
Highly accurate production with reduced cycle times
Koenig & Bauer relies on innovative manufacturing technologies in order to ensure that its skilled workers can also make full use of their expertise. The most recent example of this is the Frame Production Division, where the company has invested in five machining centres from DMG MORI. “This project was a turnkey order based on our workpieces in which everything was carried out by DMG MORI, from the design of the equipment to the tools and on to include installation and final acceptance”, recalls Ewald Baumeister. The aim was to produce high-precision volume components, including printing units with lengths of over 2,000 mm, more productively than had been possible with the previously available resources.
DMG MORI met the demands placed on productivity in this project with three DMC 210 U machines, including one equipped with a changer for five pallets, plus a DMC 270 U with an RS 4 pallet pool. Ewald Baumeister mentions the significance of the pallet changer: “It is important for us to prepare orders parallel to primary machining.” This was the only way to utilise the full capacity of the machines in 3-shift operation. The DMC 270 U is the highlight in this constellation, as this newly developed portal machine was installed at a customer’s by DMG MORI for the very first time. With a work area for workpieces of up to ø 3,000 mm x 1,600 mm, the 5-axis milling centre has more than enough space to accommodate the large printing units of Koenig & Bauer.
While the majority of the volume components are machined completed to a high level of precision on the DMC U lathes, the constellation also includes a DIXI 270 for workpieces with an even higher accuracy requirement, and like the DMC 270 U, this is also a prototype from DMG MORI. The machine owes its precision to the use of scraped guideways. Scraping is carried out by hand for over 500 hours and guarantees absolute straightness and evenness of the linear guideways, thus enabling the machine to achieve a volumetric accuracy of 7 µm. “So in precision machining we push to the very limits of what is physically possible,” says Ewald Baumeister showing how impressed he is with the machining results. “Given the enormous size of the components, this is a globally unique machine configuration.”
Koenig & Bauer works in a range of precision that demands an extremely stable peripheral temperature. This applies in particular to the equipment of the DIXI 270: a powerful cooling unit controls the heat-generating components like the spindles and motors, while the control cabinet is insulated to the machine. However, as the ambient temperature can also have an impact on the precision of the components, a climate chamber was built around the DIXI 270. This enables the temperature to be kept at a constant 22°C. The workpieces go into interim storage in a lock until that have reached the desired temperature. Ewald Baumeister clarifies the need for such measures. “Every temperature difference of one degree results in a deviation of a hundredth of a millimetre over a length of 1,000 mm.”
DMG MORI was able to completely fulfil the aim of the company with a combination consisting of DMC U machining centers and the DIXI 270. “We now achieve the necessary precision for our large components in far shorter cycle times”, says Ewald Baumeister. He sees the five machines as an important investment in the future: “The goal after all, is to ensure Koenig & Bauer remains competitive in the long term. Innovative production technologies are an element that is just as important in this respect as our experience in the production of printing presses.”