Multi-cylinder flexographic printing
More sustainable, valuable, flexible, efficient – and fit for the digital future.
Gearless and highly efficient: With directly servo-driven cylinders in every print deck and motion control from winder to winder, the evolution on stack-type flexographic presses from Giave achieves the high quality of classic central cylinder counterparts. This approach has gained widespread acceptance because it is extremely flexible regarding format, process and customization while the job change is carried out without the need for tools in just seconds. The latest control and drive electronics from Siemens already make today’s machines ready for the digital world of tomorrow.
For several years now, the converting/printing sector has been suffering from declining profit margins, and investment in innovation has become the main tool for compensating this deficit. The main areas of investment have been directed both at increasing revenue and decreasing costs. Consequently, the investment in increasing income has generated the need to innovate with new products and/or different segments in a more ecological way, making us stand out with print quality and sustainability/environment being the drivers. Additionally, the investment in costing has boosted automation and digitalization.
Metaphorically speaking, the Spanish Machine builder Giave has squared the circle in this respect: its flagship Flexographic Printing Machine Mizarflex achieves the high-quality level of a central impression cylinder press (CI) with its compact stack design. At the same time, users can benefit from a whole range of additional benefits which can be helpful for increasing profit margins. Above all, it offers a flexibility in the printing process that is unattainable with CI machines. Key factors are high-precision single and direct drives on all axes and a high-performance motion controller across the line. The combination of state-of-the-art control and drive electronics from Siemens is the basis for an integrated process control as well as for the successive digital transformation of processes at both machine builders and end users.
The seamless control and direct drive technology from Siemens plays a significant role in the high degree of flexibility, print quality and cost-effectiveness of our new Mizarflex stack-type machines. This means that both we as machine builders and our customers are ideally prepared for the unknown opportunities that will emerge from digitalization.Oriol Ginestí (Owner and CEO Giave S.A.)
Productivity, efficiency and sustainability boost thanks to single and direct drives
Stack-type flexographic printing machines with printing decks arranged on top of each other have little market appeal. The design is too static, and thus inflexible, according to popular belief. Which can be true for conventional constructions with power transmission via mechanical gears. This is exactly where the Spanish machine builder Giave started and decided to develop the Mizarflex, a truly gearless, multi-cylinder flexographic printing press, massively upgrading it in the process, especially on the electronic side. In the meantime, a complete series has been created, with - depending on the customer's needs - four, six, eight or ten printing decks, designed to work using solvent-free, water-based inks or UV LED technology, web widths from 650 to 1,650 mm and printing lengths of up to 1,200 mm. A comprehensive package of expansion units completes the solution.
In order to achieve the desired high precision, dynamics and flexibility, the designers have dissolved the printing deck, so to speak, into its single elements and implemented all turning, setting and adjustment movements via individual servo motors. Particular attention was paid to the rotational movement of pressure and counter-pressure cylinders, whose synchronization is crucial for print quality when different print lengths and production speeds are involved. And since a stable, constant web transport is decisive for the quality of multi-cylinder machines, Giave also equipped the web transport master with a direct drive solution. In close coordination, SIMOTICS T built-in torque motors were selected for these demanding tasks: liquid-cooled, high-pole, permanent-magnet synchronous servo motors with hollow shaft rotors. The stator and rotor are supplied as components, integrated into the machine and completed with bearings and hollow shaft encoders. Since it doesn’t require any mechanical transmission elements such as clutch and gears, the motor connection is extremely rigid, which enables optimum controllability and ultimately, constant high printing quality. The entire drive train is about 50% shorter and does not require a lateral installation space, such as for belt drives. This gives the designer maximum freedom in mechanical design. The small number of components also minimizes maintenance and warehousing.
Highest precision and repeatability are the requirements for setting and aligning the plate cylinder and anilox rollers. SIMOTICS S servomotors tailored to this application are commonly used. In addition, machine builders are often inclined to use another servo motor of this series to achieve precise lateral adjustment and thus make the control accuracy in the side registration even more flexible. This means that each printing deck can be equipped with up to eight servomotors. For constant web transport, the unwinders and rewinders for rolls with diameters up to 1,600 mm are driven in exact synchronism.
The coordination of more than 60 axes, depending on the machine configuration, is handled by a powerful, high-end motion controller from Siemens with an integrated register control (see below) in combination with a fail-safe SIMATIC PLC. All of this based on proven technology functions from the open software package Print Standard. One state-of-the-art feature is machine-wide, real-time communication via Profinet IRT (isochronous realtime).
With the naked eye there is practically no difference in quality compared to a CI machine. We achieve this through the high degree of automation, and the intensive use of high-performance control and drive electronics with direct drive technology. We therefore refer to this machine as the "eCI", our electronic CI machine.David Darder (Giave S.A., Head of Sales)
The impressive result is consistently high printing quality at production speeds of up to 500 m/min—almost twice as fast as comparable conventional (mechanically) driven stack-type machines and a correspondingly higher output.
Giave has also worked on automating processes and making them more efficient in order to improve changeover times. The company transformed the absence of the central drum into an ergonomic advantage, enabling much shorter setup/conversion times than can be achieved with an equivalent automated CI machine. Along with the reduction in waste, this is clearly a decisive factor in the search for benefits and sustainability.
And right from the design stage, it was taken care to minimize energy consumption (and thus the carbon footprint) and to interact more sustainably with the environment.
Thus, the continuous servo motor approach also has energy advantages. Because all transmissions are eliminated and a precisely dimensioned motor is used for each individually driven cylinder, energy consumption is reduced by up to 20%. In addition, the motors feed braking energy back into the common DC link, which saves further energy during operation. The unwinders and rewinders run almost energy-neutral, for example. And thanks to water-cooled torque motors, there is no need for energy-intensive air conditioning in the vicinity of the machine.
The unified servo motor approach enables highly flexible, yet extremely precise web guidance and, with appropriate job preparation, production changes in a matter of seconds.Toni Palma (Giave S.A., Head of Technology)
Consistent extremely high print quality: Beyond 90 lcm thanks to integrated register control
The integrated register control (IRC) inside the Siemens automation system makes high quality and minimal start-up waste possible. The design is modular, and even the user interface can be customized by the machine builder to suit the functions of the respective machine. The combination of one TRC 7000 color camera each for front and back and an intelligent TRC 3000 wedge-mark sensor for aligning double-sided printing leaves all options open. Right from the start, optimum web guidance is ensured, both in machine and cross direction. This reduces the start-up waste from over 100 m in conventional machines to less than 10 m. Producing as little waste as possible is not only a cost factor, operators also improve their carbon footprint by using raw materials more efficiently, which is becoming more and more important.
Extremely flexible web handling – also for Insetting
Without the large central cylinder, stack-type machines, with their better accessibility, have a much more compact design printing unit, with up to 25% less footprint. Far more important, however, is the much more flexible, yet precise web routing through the individual printing decks. The ability to control the web tension makes it very easy to implement a wide range of color set-ups, depending on the machine configuration (see table), such as front and back printing without turn bars. In the so-called insetting process, the reprint of an already printed web, even a job with up to eight colors (8-8) on each side in exact register is possible in two separate runs. A customized Mizarflex with only four printing decks, for example, also gives the operator the freedom to deliver eight-color jobs (8-0) on one side also.
This added values also increases the ability to yield a faster payback.
Even higher print quality can be installed later: Learning Error Compensation (LECo)
Another way to improve quality via the drive system is the Learning Error Compensation (LECo) function. This self-learning control algorithm uses the drive control behavior to detect cyclic disturbances caused by the typical vibrations of flexographic printing due to the unevenness of the clichés (bouncing). These are compensated automatically to avoid any negative impact on the print result.
Last, but not least: In order to realize the highest print quality even faster right from the start of production, the machine builder Giave has developed an innovative pressure control between the cylinders using standardized interfaces to the motion control system. This allows the "contact point" between the cylinders to be located electronically with the help of drive data.
Built-in technologies of the future - Open for extensions
Besides the incorporation of UV LED drying as a solvent-free printing technology, Giave has been able to generate several optional expansion packages that show how open and flexible the automation concept is. For example, Mizarflex lines are available on customer request with a separate digital printing unit integrated into the overall process. This makes it easy to achieve special wishes such as product-specific or on-demand prints, or special seasonal- or regional prints. Here, too, the described drive concept on the transport rollers ensures a high-precision web transport.
Based on the modular Print Standard software package, we can also develop and implement customer-specific special solutions very quickly and easily.Toni Palma (Giave S.A., Head of Technology)
Ready for the digital future
Modern servo drives alone generate a wealth of meaningful data. Features such as LECo from Siemens and applicative customer solutions such as Giave's pressure control show how this data can already be used effectively today. And how the printing process and quality results can be improved without installing additional sensors. In addition, the digitization portfolio for the collection, analysis and evaluation of this and many other data continues to grow. Among other things, this includes industry-oriented, high-performance networked (I)IoT devices and innovative software to tap previously unrecognized, unutilized optimization potential. "This allows, for example, enhanced data-based services for preventive, condition-based maintenance, enabling even higher availability and thus productivity, or for continuous process optimization, resulting in even more transparency and efficiency during productive operation," says the Giave management. With control and drive technology/electronics from Siemens, both machine builders and users have wide access to the digitization of their processes in the future.