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FLEXO Magazine : June 2014
use some of our latest experimental screens throughout this evaluation process. These screens may contain further potential for improvement for flexography. They were deliberately developed for an imaging reso- lution of only 2,540 dpi and may therefore be used with conservative plate making equipment. Their strength lies in the partic- ular small first printing dot that does come very close to offset lithography. NEEDS & CHALLENGES It may be safely assumed that the function of DFTA Planoflex depends quite strongly on the precision with which the aforemen- tioned shallow relief depth may be held consistently over larger printing plates. This is the only way we can succeed in establishing consistent pressure between printing plate and substrate. Achieving such a flat relief under the usual processing conditions where relief depth is being determined through the so called backflash exposure appears to be impossible. Floor thickness variations of approximately ±40-μm., which are typical and nonproblematic with usual platemaking, may not be tolerated with DFTA Planoflex. We have developed a reliable alternative that produces variations of only ±10-μm. consistently. At this point in time the extra steps involved do prolong preparation times for platemaking by a small amount. However, should DFTA Planoflex succeed over a wider area of the market, these preparations may be automated relatively easily. The biggest challenge we have faced so far is the arrangement of the horizontal gap, which cannot be avoided if printing plates (rather than seamless sleeves) should be used. The challenge here comes with the fact that in order to achieve full contact over the entire repeat length, the gap needs to be closed almost completely in order to not reintroduce the vibrations. However, we have found a working solution already and there are still a few potential alternatives in sight. Using DFTA Planoflex with seamless sleeves has been demonstrated to work successfully a number of times already. Generally, the borders of the applicability of this new flexo derivative are not fully known and must be evaluated still. It must be assumed that DFTA Planoflex may not be suitable for all parts of the market. The DFTA Technology Center and its partners still have to perform a lot more testing and evaluation, but the prospects are bright. n About the Author: Dr. Martin Dreher is the scientific leader of DFTA Technology Center in Stuttgart, Germany. He spent a portion of his career working with Du- Pont Cyrel as technical application specialist and as team leader on the Cyrel team. He has also worked as a professor at the Hochschule der Medien in Stuttgart. He has written several trade articles. JUNE 2014 | FLEXO 87