The finer, the better

25.06.2009 The new production plant for sheet-fed offset printing inks of Epple Druckfarben AG in Germany has been up and running since August 2008. The facility, designed and constructed by the Buhler Grinding & Dispersion business unit, is considered by the industry to be an exemplary installation which sets the trend in advanced printing inks manufacture. The Epple Druckfarben company is acknowledged internationally as a seasoned specialist producer of high-grade sheet-fed offset printing inks. The company, based in Germany, employs some 200 persons. Its steadily growing share of exports go mainly to other European countries. But also Asia and America are markets of appreciable importance. Sheetfed offset printing inks from the Epple company are applied for printing high-quality matter such as magazines, catalogs, brochures, calendars, and refined art prints with the finest pigmentation. In addition, Epple also manufactures special odorless and low-migration inks for printing food packaging materials.

From manual to fully automatic
To date, production at Epple Druckfarben AG was only automated to a certain extent. But today, batch processes using mixers, three-roll mills, and large ink tubs is only suitable for making certain product groups. This is because production volumes are growing while the market expects steadily rising requirements to be satisfied in terms of supply service, flexibility, and economy. The Epple management therefore decided in 2004 to thoroughly update its production facilities. Executive board member Dr. Wolfgang Josten, who is in charge of production at Epple, says: “By building the new plant, we were pursuing three goals: We wanted to increase our efficiency, further enhance the quality of our products, and maintain this quality at a very constant level.” Last, not least, output was also to be increased to several ten thousand metric tons of printing inks annually. Two or three operators were to be sufficient for running the plant.
In order to achieve these goals, a fully automatic production plant was to be constructed for the four offset ink colors black, blue (cyan), red (magenta), and yellow. These four production lines were to be housed in a new building behind the existing production halls on a surface area of about 1500 square meters. The fully automatic plant would be operated from a raised control center overlooking the factory.

In two stages
The company management of Epple Druckfarben AG entrusted Buhler with designing and constructing the new plant for manufacturing sheet-fed offset printing inks. This would continue a long and proven customer relationship which dates back to the year 1919. Wolfgang Josten: “For decades, Buhler has established an outstanding track record with our company as a reliable partner and provider of top-notch dispersion technology.”
The Buhler plant designers and engineers started working on the project at the end of 2004. In the spring of 2006, the first two ink lines (black and cyan) went on stream. One year later, installation of the two other lines (magenta and yellow) started. In November 2008, the complete plant of Epple Druckfarben AG was commissioned and ready for regular production.
The result of this four-year engineering and construction period is an exemplary, state-of-the-art overall plant for manufacturing offset printing inks. “Our expectations were clearly exceeded,” says Epple speaker Joachim Erlach, praising the job done by Buhler. “The plant is running to our entire satisfaction. What Buhler has built for us sets the trends in our industry in terms of plant and product quality.” Mark Traber, who as an area manager is in charge of the German market, confirms that the new production facility of Epple Druckfarben AG serves Buhler as a showcase plant. “At Epple, we have built a four-color plant in a tightly dimensioned space whose systematic automation and high-grade ink manufacturing processes are exemplary.”

From the raw material bins to the finished-product tanks
The production plant consists of four identical lines set up in a parallel configuration. Each line starts with the bins holding the ink pigments, which are supplied by the chemical industry. In the first stage, a batch mixer mixes the pigments with special oils as a vehicle or carrier fluid. This mixture is transferred to an intermediate tank which continuously feeds the dispersion section.
Actual dispersion is carried out in an initial stage in a K240 bead mill. Here the pigment particles are uniformly reduced at a temperature of about 100 degrees Celsius. The ink concentrate then obtains its gloss properties in a three-roll mill (type SDVE-1300), where the ink is additionally cooled to 50 °C and deaerated. In the last stage, the ink concentrate is directed to the finished-ink tank, from where it flows to the dilution system and the installation for filling it into cartridges or other containers. In this operation, it is additionally possible to make customer-specific adjustments. The new four-color production plant is controlled from a raised control center. From there, the entire ink manufacturing process is controlled by the new Buhler automation software WinCos. It records the exact consumption of the individual raw materials and accurately logs the production of the individual batches. The logs serve for quality assurance and for tracing production.

Improved dispersion
Industrially manufactured ink pigments are a very expensive raw material. Their purchase price accounts for the largest share of the raw material costs incurred in the production of high-grade offset printing inks. Therefore, the degree of fineness achieved in the dispersion process is a direct benchmark for the customer value of a new plant for industrial production of offset inks. “The finer the pigments are ground in the bead mill, the larger the resulting particle surface area,” explains Epple production manager Wolfgang Josten. “Or, in other words: The finer the grinding action, the better the pigment quality and utilization rate. Thus, Buhler is helping us with its advanced technology and process mastery to maximize the efficiency of our production activities.”

Bead mill and three-roll mill – the heart of the dispersion process. Bead mill and three-roll mill – the heart of the dispersion process.