In India, the use of a fixed set of 7-color inks has already been adopted by a couple of commercial and packaging printers who use it on 7-color offset sheetfed presses as well as web-fed flexo presses. Both Esko’s Kaleidoscope and Heidelberg’s Mulicolor have thus far been implemented. Increasingly it is being talked about for flexible packaging and Bobst’s 20Seven CI flexo press highlights the company’s strategic commitment to develop Extended Color Gamut (ECG) solutions for a variety of printing technologies and applications and recognizes the process in terms of graphic quality, consistency, cost and time efficiency. Flexible packaging printers from India also took part in the Open House at the Bielefeld Competence Center of Bobst Bielefeld, Germany. The Open House was attended by over 400 leading printers and industry suppliers from over 20 countries over two days on 27 and 28 February 2018.
Launched in February 2018, the Bobst 20Seven CI flexo printing press is ready to handle evolving packaging requirements, with the company’s technical development focus on making the press especially suited for the ECG process. This has been achieved by maximizing process consistency and repeatability, which are the fundamental factors that enable to reap all the advantages derived from the use of ECG. The solutions devised that relate to mechanical design and process control make the new press a good fit for the requirements of the 7-color Extended Color Gamut printing process, but it goes without saying that the technical features and improvements make the machine deliver increased efficiency also with conventional printing. The press engineering has indeed succeeded in improving the machine functions that are fundamental to ensure process repeatability in wide-web flexo printing.
smartFLO inking and chamber doctor blade
Controlled inking is of great importance in ECG printing and the new features of the Bobst smartFLO inking system and chamber doctor blade deliver predictable, stable and controlled printing results with both solvent-based and water-based inks. This is achieved by optimizing the temperature and flow of ink, thereby eliminating the variations in the ink viscosity that can derive from environmental factors such as temperature and light, or from inconsistent ink metering owing to pumps. To achieve accuracy and consistency in flexo printing, press frame vibrations should be eliminated by firmly and accurately locking the print decks’ bearings. The 20Seven’s bearing are set between top and bottom linear guides; the bolts are tightened using a pneumatic tool which always applies the same torque, thus avoiding the variables derived from manual operation by different operators. The cylinders are precisely kept into place owing to the triangular geometry of the company’s triLOCK system. The third important aspect is the press drying system, which should be suitable to achieve the required drying consistency at high speed with tenure for register not only with solvent-based inks but also with water-based applications which are on the rise. The new Bobst FSM (Full Surface Matrix) dryer provides uniform drying at reduced temperatures thereby eliminating the issue of substrate stretching and dramatically enhancing register accuracy at high speeds by evenly pushing the web against the CI drum. Furthermore, in terms of repeatability, Bobst’s CI flexo presses can rely on its smartGPS system. The offline registration and pressure setting system, in addition to the well-known performance of minimum waste at start-up and job changeovers, is also instrumental in increasing the lifetime of high resolution plates by printing the real diameter, thus avoiding any distortion of dots that can build up when the rotational speed of the printing system does not perfectly match the format. All of the 20Seven’s new features enable users to take full advantage of the opportunities of the extended color gamut to reduce manufacturing costs, increase consistency and reduce errors and variables due to manual setting. There is no need to change inks and washing the print deck between jobs, no need to keep a large inventory of spot color inks and no time needed to mix special color inks. Furthermore, the system enables a guarantee to brand owners of the color consistency and repeatability of the packaging of their products every time they are printed, even if long time apart or in plants located in different parts of the world.
The Bobst 20Seven is available in 8- and 10-color configurations in web widths of 1050, 1450 mm and a repeat range from 370 to 1200 mm. The standard speed is 400 meters a minute, with optional speeds of 500 or 600 meters a minute.
