Computer Direct Roll Reel Flexographic Technology

In the NEW millennium, flat flexographic plates will face challenges from reel etched plates. In the fifteenth century, Gutenberg used lithography when it printed ink on paper for the first time. The original flexo printers used an offset printing plate to transfer the ink to the material. They worked by rolling the flat printing plate onto the printing cylinder. When the photosensitive resin revolutionized the flexographic industry in the 1970s, the flexographic plate was still lithographic, but it was not molded directly from the film to the plate. Gutenberg's letterpress printing technology has been replaced by the widely used rotary printing. Even though the use of photosensitive resins has made plate making technology develop in many ways, despite the change of the century, there has been no change, that is, the flexographic version is still lithographic. However, with the development of computer-to-plate technology, the plate can be made into the shape it uses - round. Although computer-to-roller etch platemaking is not entirely new, the technology has begun to change in the past few years due to the development of the technology itself and the increase in the number of printers using dedicated digital workflows. . Thomas Frater - CEO of AKL Flexo Tech, whose North American headquarters is located in Cumberland, RI - states that "With the reduction of time to market, low-cost transport packaging, improved accuracy, and improved overall print quality, the future of packaging CTS is a modern technology.” Recently, the merger of suppliers including AKL Flexo Tech, Barco Graphics and DuPont Cyrel Packaging Graphics is underway, and it is trying to promote computer-to-machine technology. Some of the ideas and information in this article came from the narrative of some companies in Iselin, New Jersey late last year. Made round, using circles Since the beginning of the 20th century flexographic printing, the printing plate has been produced either by casting a flat rubber plate or by imaging the image in a flat (thin layer or liquid) by negative or mask exposure. ) on the photosensitive resin. Although the use of lithography can achieve excellent image integrity, especially with modern prepress and platemaking techniques, the printed image is always slightly different from the original. A simple reason for this phenomenon is - - Although the flexographic plate is flat, it is printed in a circular manner. Flat printing plates made with standard exposure techniques must eventually be rolled onto the roller. Because the outer edge of the plate is stretched by a larger diameter than the edge of the platen, the plate is distorted. Before printing, this distortion was pre-calculated and resolved. Of course, even with the most advanced prepress workflow, it is easy to overlook some mistakes. It is very easy to distort and stretch the plate in various ways by installing a version, which cannot be calculated in advance. Although the new type of photosensitive resin has an excellent shape retaining property, some distortion is inevitably generated. "However, how accurate your plate and calibration device is, when you put a plate on a press or mandrel and calibrate it, the material is still very easy to deform and change size." Dave DiTallo said that he is Schepers-Ohio - - Production managers who are known for producing roll engraving equipment. On the other hand, with the development of computer-to-plate technology, webs are pre-installed on rollers and etched in a "circumferential" manner. The final printed image is exactly the same as it was when it was designed. Although the state-of-the-art prepress system can accurately calculate and compensate well for image distortion caused by the lithographic plate being rolled onto the cylinder, this process is not perfect. In CTS, the image is directly etched onto a round roll plate. According to Barco Graphics' Ian Hole, the CTS system can substantially solve ink problems. Saying Goodbye to Film One of the key advantages of using photopolymer plates is that they reduce the need for plate imprints—reducing the time and expense while increasing the ability of printed images to fully restore originals. CTS no longer exposes the photosensitive resin plate through the original film. Instead, the photosensitive resin web is made by a "mask" coating, which is laser-fused and exposed directly through the photosensitive resin plate to create a negative image directly on the web. In sequence, the laser is controlled by a computer. The computer first reads the electronic file and then tells the laser where and when it is exposed. And, restore the originals in one step. “The most significant advantage of electrophotographic imaging on any flexible web or plate is that it avoids the use of film products and the loss of detail through film exposure to photosensitive materials,” said Dave DiTallo of Schepers-Ohio. , information processing, chemical reactions and time are saved.” Because the film exposure and development process is a major cause of waste of materials, conservation should also be considered for environmental reasons. Running in rotation The steps of reducing the printing process not only represent an advantage in faithfully restoring the original and reducing the cost, but also have an advantage in running time. In principle, as long as the picture production is completed, the computer-to-plate system can directly etch the electronic file to create an installed plate. Once the etching is completed, the plate can be printed - no need to install. Of course, the etching process takes time. , but not much. In Ohio's Schepers, a CNC system with a single laser can move at the surface of the plate at speeds of 1-3/4 inches per minute - meaning that a 36-inch plate can take only one hour Complete the etching. Using a dual laser system means cutting half the time. This is fast, but if the plate is etched for a six-color or eight-color wide web press, the time will be doubled if there is only one etching machine. Obviously, it is very difficult for a busy factory to use only one machine to complete all the plate making work. Seamless Printing Plates Unless you want to make freely distorted images, circumferential etching is ideal for producing "seamless" printing plates. Packaging manufacturers, especially webs, are used for decorative printing and do not like to have a plate joint on their products. For packaging manufacturers, seams often mean that they have to design their products and arrange the production process so that the seams are folded into the seams. It is a natural process to directly etch a 360-degree circular image on a seamless, pre-installed plate. The ability to produce seamless plates reduces the advantages of gravure printing. As flexo printing has increased dramatically in quality in recent years and in terms of running time and plate cost, there is no reason for customers to choose gravure printing instead of flexo printing. To this end, while the direct performance of computer-to-plate etching is irrelevant to the most important applications, manufacturers have emphasized that other technical advantages have attracted a large number of users. DiTallo said that "the printing plate does not have to be seamless, only 3% is seamless." Limitations Of course, there are some obstacles to the promotion of the direct plate-making system. Usually, the first is the cost. In addition to the cost of circumferential etching equipment, there are additional equipment associated with its own version. Although with the increase of the volume, the cost of the reel version can also be reduced, they are currently more expensive than a single sheet or a liquid photosensitive resin plate. In addition, the size of the installed roll plate makes it more difficult and expensive to transport and store. DiTallo said: "Depending on the needs of the production plant or printing plant, it is much easier to transport flat plates in different sizes and specifications than to provide full-size and diameter roll plates." The same number of roll plates and lithographs or Photopolymer plates are much more expensive than transportation and storage. Another obstacle is the need for equipment and workflows that can satisfy the etched web version. This production process requires a printer that supports a roll version. And, over time, more and more printers are capable of installing roll plates. However, for those printers who have conventional printers that cannot handle roll plates, it will not be economically feasible to switch to them unless they are updated. First of all, digitization However, the printing companies that are making changes to computer-to-plate technology must be careful not to go too fast. At the AKL/Barco/DuPont product tour, the lecturer spent more time and effort on the use and implementation of an all-digital workflow than they actually explained on the roll plate. Obviously, the workflow is very important. Simply put, successful implementation of CTS requires digital workflow experience. If a company hasn't yet adapted to install-run digital workflows, don't be in a hurry. Hole reminds companies that have not yet verified digital workflows to upgrade to CTS. This means: Before attempting to use computer to make plates, it is necessary to install and operate a complete digital workflow. Therefore, even if the digital etching computer direct plate making technology has an advantage in printing quality, in fact, the start-up costs and learning difficulties associated with this technology will make its promotion a gradual process - just like the flexographic printing technology itself. . DiTallo said: “This is a new field for flexographic printing, and those who have already used this technology have become more satisfied with the results, but compared with standard plate exposure and printing technology. The number of users is still very small. 2000 will be a new year." Frater described the future of circular imaging more directly. He said: "As we know, CTS will redefine the flexographic printing world."