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FLEXO Magazine : July 2013
dust free, uniform sheet and makes it possible to gain all the benefits of laser engraved elastomeric plates in a cost competitive manner. Other benefits are derived from the nature of the material itself, which is a black synthetic ethylene propylene diene monomerethylene (EPDM). This material is not sensitive to UV light or ozone and is universally resistant to all flexo ink systems. It does not swell during printing. CONSISTENT, UNIFORM, COMPRESSION Materials can be supplied intheformofaroll,soasto minimize waste and reduce storage requirements. A built- in compressible layer, offers the flexo printer two major addi- tional advantages: • The plate can be mounted on a thin, hard double-sided tape, enabling significant saving by not having to buy costly compressible double-sided tape • When a plate is mounted on double-sided foam tape, the carrier sheet at the plate side of the double-sided tape, acts as a barrier and compromises the compressibility of the tape Compression across the elements of the plate is much more uniform. As a result, pressure halos and cupping are minimized. A further benefit comes from the fact that the com- pressible layer itself is more resilient to repeated compres- sion than soft foam tapes. It does not suffer from problems of compression set, so it provides greater longevity. COMPACT, EFFICIENT LASER The “PremiumSetter,” which incorporates a fine beam fiber laser, is the key component of “PremiumFlexo. ” Laser diodes are used to provide the energy beam that is sent down the fiber optics which produces a stable uniform laser beam and directs it to the point of engraving. This results in a compact, efficient laser with excellent beam quality and a large focal range. The “PremiumSetter” is capable of engraving plates, plates-on-sleeves (with a sealed seam) and continuous sleeves. Where plates are concerned, an elastomeric sheet is first cut to the correct size for the image required. In readi- ness for laser engraving, this sheet is then held in position by means of a vacuum adaptor, for which a vacuum pump is available. Sleeves are loaded onto an air mandrel and held in place by means of cones. Alternatively, there is the option of cantilever mounting for easier loading of the sleeves. Job production parameters can be set up remotely and then transferred to the “PremiumSetter” when required. This reduces setup time and optimizes the laser. Workflow is controlled by a job ticket station that enables all produc- tion parameters to be centrally entered. Ease of operation is facilitated by a Windows operating system. As the job tickets are based on SQL databases, it is easy to archive the data and retrieve it again for repeat jobs. Laser efficiency is enhanced by using a fixed cutting tool to remove areas of the printing form outside the boundaries of the image content. These areas are defined and removed to a relief depth of 1mm before the start of the laser engraving operation. Depending on the nature of the image, savings When the cushion layer is integrated into the plate material itself, as is the case in this illustration, pressure on the surface of the plate during printing is transmitted directly down to the cushion layer. Reducing the height of the highlight dots means that when the print impression is set up, all other elements of the plate print before the highlight dots, thus making it possible to get good pinhole-free solids and minimize highlight dot gain. www.flexography.org July 2013 FLEXO 51 COMPRESSIbLE LAyER UNdER IMPRESSION