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FLEXO Magazine : June 2014
harmful characteristics for us and we gain a couple of extra advantag- es as well. Image 1 shows the principle of DFTA Planoflex with a cross section through the nips between anilox roller and printing plate on one hand and between printing plate and substrate on the other hand. ADVANTAGES & IMPROVEMENTS Just like the entire European flexo printing market, we use photo- polymer plates at the DFTA Technology Center. Their processing cycle times and costs will eventually be governed by the depth of the relief that has to be washed out or processed thermally. With DFTA Planoflex and a relief depth of only about 0.004-in. (0.100-mm .) our processing times for main exposure, washout and drying or ther- mal development have been shortened drastically. For instance, the potential washout speed we could use with DFTA Planoflex plates exceeds the maximum mechanical speed of the washout machine. Hot air drying, usually the bottleneck of conventional plate making, takes 30 to 45 minutes now. Consequently, we save a lot of time, solvent and energy, or gain a lot of extra capacity. In the slipstream of the flat relief of our DFTA Planoflex plates anoth- er inestimable bonus comes along: the improvement of the registra- tion quality in multicolor printing. We yet have to examine this more closely, but it looks like the usual design dependent differences in elongation that would otherwise occur with our flat washed printing plates don’t seem to occur anymore (see also the so called “frame effect”). Moreover, the relatively thick layer of photopolymer that is now present everywhere over the printing plate (with a printing plate thickness of 0.045-in./1.14 -mm ., the floor is 0.040-in./1.02-mm . thick, which means a 0.033-in./0.83 -mm. photopolymer after deduction of the carrier base) seems to minimize the otherwise usual distortions of the color separation plates and thus cause better registration quality. During the printing process itself we have observed the following advantages over the traditional flexo operation: • Vibrations and horizontal streaks, if they occur at all, will only occur in a very narrow speed window and are therefore very easy to master • The process of setting up the press is eased through the simpli- fied handling • We find register more quickly because there is not that much “av- eraging” of different register requirements to be done • The differences between “heavy” print forms (bearing a lot of area coverage) and “light” ones have diminished, most proba- bly because all of them run at the aforementioned full contact circumstances anyway Due to the limited amount of experience there is still some uncer- tainty, but we do expect significant savings in substrate and time for the press setup. Print quality is equivalent to the usual flexographic handling procedure, but it should be mentioned that we tend to 86 FLEXO | JUNE 2014 3 2 4 1 3 2 4 2 1 2 1 3 2 4 Key: 1: Anilox roller 2: Elastic printing plate surface 3: Substrate 4: Impression cylinder Image 1