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FLEXO Magazine : March 2011
Technologies & Techniques Optimizing Ink Release from Your Anilox Roll Nets Savings Minimal Waste, Consistent Color & improved quality By sean Teufler Stop printing unnecessarily thick ink film. Pay close attention to the color matching process. The secret to savings, on both of these fronts, requires some basic groundwork, namely optimizing the ink transfer from the anilox roll. There are three approaches to fine-tuning ink scientifically: 1. Determine the optimum printable ink film thickness us- ing a banded roll. 2. Adjust the anilox roll inventory. 3. Set up a system to maintain the desired volumes. First, discuss your options with your ink supplier and ask whether the supplier has any new products that will reduce ink film thickness. Aim for a combination of correct color strength and optimum printability. It is simple to achieve either color or printability, but not both, without calibration by testing. Trial and error is one method for determining the right ink film thickness for your application, but it is too inefficient to recommend. Using a banded roll is much more reliable, ef- fective and economical. Banded rolls continue to be the best tool for evaluating color strength and printability, without the concern that no range has been established. Designing a banded roll is simple. Take the following steps: • Have your ink supplier quote the ink volume deemed most successful in achieving consistent lay-down of sol- ids and color strength on the substrate you plan to use. • Make that recommended volume one of the center bands. Then choose two to four more that are higher and lower in volume. (See Table 1.) These different volumes serve to calibrate and evaluate the range the ink has before producing undesirable print effects, such as loss of color, poor transfer/mottle and substrate dive. • Run a trial with the desired plate/tape and plate screen- ing technology and evaluate the results using a calibrat- ed spectrophotometer. TAble 1. Target Volume, Ink Supplier: 1.8 BCM Plate Characteristics: 150 dpi, 2% minimum dot Banded roll design: 900 900 900 1000 1000 1.6 BCM 2.0 BCM 1.8 BCM 1.8 BCM 2.1 BCM All 60 Degree 900 1.6 BCM: Lower volume if ink comes out strong 900 2.0 BCM: Higher volume if ink comes out weak 900 1.8 BCM: Target line and volume 1000 1.8 BCM: Same volume, potential cleaner print 1000 2.1 BCM: High volume if 1.8 BCM target is low Certainly, you can take any of the most modern, stronger ink systems and extend them heavily to get the desired color strength. Doing so, however, will provide no savings in ink film thickness and will sustain another variable--shifting color strength. Experience has proven that taking advantage of a thinner ink film thickness through banded roll ink film optimization will provide desirable color and printability characteristics, as well as savings down the road. Cost reductions associated with use of thinner ink film alone justify the optimization pro- cess. For example, if you are currently using a 4.0 BCM anilox roll and you can drop to a 2.5 BCM anilox roll yet achieve the same color strength, why not realize a 37.5 percent decrease in printed ink usage? AUDIT & INSPeCTION With thinner ink film requirements and anilox roll specifi- cations in place, the next step is to determine whether your current anilox roll inventory is appropriate for what you plan to do on press. More than likely, at least a few anilox rolls on hand will fit the profile, but there may not be enough to meet the requirements generated by the number of print decks Contact your anilox supplier for the right tools and expertise to design a banded roll. Photos: Harper Corporation of America. www.flexography.org MArCH 2011 FLeXO 41 FLX_March11.indd 41 3/18/11 1:33 PM