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FLEXO Magazine : October 2009
36 FLEXO OCTOBER 2009 www.flexography.org you factor in the elimination of the solvent recovery system and necessary containment, you end up with a compact poly- mer sleeve system without special room considerations that a solvent system has. Although the system itself is small, the output covers most popular press widths. Sleeves up to 57in. wide with a maxi- mum repeat of 40in. are possible, and the optional multi- sleeve mounting system allows printers to combine sleeves for wider presses or when there is a need to mount smaller sleeves in varying lane configurations. In addition to being smaller, the thermal sleeve system is also faster. Start to finish for a 42in. sleeve with a 20in. repeat---including digital imaging time---takes about an hour, and you would expect to be able to complete all the sleeves for an eight-color job in well under four hours. This is signifi- cantly faster than a solvent sleeve process system, where the first sleeve would come out in approximately four hours and it would take about seven hours until the last sleeve emerged. It's worth noting that the access time for the first sleeve in a direct laser-engraved rubber workflow is also about an hour, but the nature of the process is such that each subsequent sleeve will also take an hour, so it would be eight hours or more before your final sleeve was engraved in that workflow. Sleeve handling has been simplified in the thermal workflow as well. In a solvent processor, sleeves need to be removed from the imager and mounted onto a metal shaft using precision-fit end pieces for exposure and process- ing. The cost of this additional processor tooling can quickly add up, and the storage and handling of these tools adds to the labor. The thermal system has eliminated this need. The main exposure unit is designed so that the sleeves are simply placed vertically onto a fitted end piece and are covered by a lid to prevent the edges from being exposed. The thermal processor utilizes a unique "loose fit device which places the sleeve into position around a cylinder and a movable arc. The "loose fit allows a wide range of sleeve repeats to be pro- cessed without the need for specialized tooling. Once loaded, the sleeve is brought into contact with the developer roll and the unexposed photopolymer is transferred to the non-woven fabric. The used developer rolls are removed by DuPont and disposed of in a waste to energy system which minimizes both the environmental impact and the problem of waste disposal. MARKET FIT Clearly the thermal polymer sleeve system represents breakthrough technology, but does it fit the needs of the flexo industry in North America? As we've seen, continuous print sleeves have been available for many years and have cap- tured only a tiny percentage of the total flexo image carrier segment. Does the introduction of the thermal system really change anything? The answer is "yes, and to understand why, we need to look at the economics of sleeve use. Whether as a raw material or in a finished form, sleeves cost more than flat plates. Even when you dial in the savings from the elimination of plate mounting, the one-time cost of a continuous print sleeve is higher than a flat plate. Conse- quently, there must be pressroom productivity improvement resulting from the use of continuous print sleeves for it to make economic sense. Experience in both North America and Europe has clearly shown three criteria which singly or in combination justify continuous print sleeve usage: Frequent Repeats Long Press Runs Very High Press Speeds The ability to facilitate high-speed change-over, the caliper uniformity and robustness of continuous print photopolymer sleeves have been clearly demonstrated, so any printer that can apply one or more of the above criteria to their operation is a potential candidate. Of course, those same attributes applied to solvent polymer sleeve systems. The key difference with the thermal process system is its accessibility. As with the original thermal flat plate system, the launch of the thermal in-the-round system introduces the concept of "just-in-time sleeve making at press side. The smaller footprint, lower cost and ease of operation coupled with the elimination of solvents and the rapid-access of the thermal system, mean that printers with frequent repeats, long runs or high press speeds can serious- ly consider the potential benefits of bringing sleeve imaging and processing in-house--- either as part of their own internal operation or in partnership with their tradeshop as a managed facility. The first external evaluation of the thermal in-the-round sys- tem has been running at a customer in Germany since Febru- ary and two more European installations are planned before year-end. The first external evaluation in a North American location is planned for early 2010. The flexo industry has been holding onto the promise of polymer sleeves for many years. With the introduction of the thermal system, it appears that the reality is finally at hand. ABOUT THE AUTHOR: Ray Bodwell is North American mar- keting manager for DuPont Packaging Graphics. Additional information and resources pertaining to flexographic packag- ing can be found at www.cyrel.com or feel free to contact him directly at firstname.lastname@example.org. A convenient sleeve loading door allows operators to quickly load and unload the continuous print sleeves. The system automatically centers a single sleeve or will allow simultaneous processing of two sleeves. TECHNOLOGIES & TECHNIQUES
Sustainable Fall 2009