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FLEXO Magazine : June2010
Technologies & Techniques 42 FLeXO june 2010 www.flexography.org successful flexographic printing now relies very little on luck and has become a more precise science over the last 20 years. All art courtesy Harper graphicsolutions. Do your operators roll the dice when selecting an anilox for the next job? Are you relying on luck to find repeat- ability in your printing process? How do you put the odds in your favor to tame the variability that costs you so much time, ink and material? The sure bet lies with anilox standardization of your printing process. Anilox standardiza- tion is truly the ideal approach for optimizing the interaction between ink, plate and anilox because it both minimizes the setup and the variability normally acquainted with process and combination printing. Converters during the FFTA 2010 Forum Las Vegas com- mented on how essential anilox standardization is to their print- ing success. Successful anilox standardization often requires preparation by utilization of banded rolls and ink proofing. When standardization is done correctly and augmented with steps of quality assurance like cleaning and verification, achievement of your printing goals is well within reach. True anilox standardization is best accomplished by selecting the anilox volume and cell opening to accommodate both the cur- rent ink performance and plate requirements. Let’s explore the approaches and look at what you need to map out your own standardization path and win at this game once and for all! Cue the Band Aniloxes are designed for two functions: delivering a set amount of ink consistently and providing dot support for plates. These two functions are defined by cell opening and cell capacity, known better as line screen and volume. We know volume dictates ink film thickness and understanding the volume requirements of your ink determines success. Selecting a volume that fully enhances the color and print- ability properties ink is the ultimate goal. Why does printability factor in? Because printability indicates whether you will print consistently the same image or dot size. That is why it is so important to ensure consistency and validity of any volume testing by comparison of samples from the beginning and end of a pressrun; because ink performance must also be figured into the calculation. For example, if the ink has stability issues, such as prema- ture drying at the volume you are using, you will discover print quality changes and as such will need more volume or an ink dry-rate adjustment. Cells per inch (CPI) has an important function of providing the highlight dot support for the fine screen work. This happens by making sure the smallest dot on the plate is still larger than the cell opening on the anilox. Contact your anilox supplier for charts and diagnosis to help you select the correct line screen for your application. Cell count and volume can also be determined by a number of the following avenues: banded rolls, ink supplier test data, proofing, and current anilox inventory. All are valid methods and can be combined to further refine the results. Let’s look deeper into these methods. Banded roll testing is an excellent method for exploring your printing capabilities and defining your process for stan- dardization. You can qualify various cell counts and volumes based on your particular print variables. To get you started, draw from your sources of technical knowledge. Ink suppliers often have test data to determine the performance charac- teristics of their ink system for dry rate, density and color. You can combine this data and with the flexographic acumen of your anilox technical representatives and select the best anilox specification to have engraved on the banded anilox. If your ink supplier does not have testing information, you can use your own prior pressruns or run a small test to get your bearings and then evaluate current capabilities and gauge potential improvement targets. It is typical to have a few bands that stretch the printing potential of the press. Re- member, since you have not confirmed what you can do yet, you may surprise yourself with what your press capabilities actually are. Banded rolls are certainly an economical way to determine your printing capabilities based on the current ink system, plate needs and press limitations, because they limit the investment while maximizing data accumulation. It is com- anilox Standardization: The sure Bet By sean Teufler • Banded roll testing is an excellent method for explor- ing your printing capabilities and defining your process for standardization. • Determine if any adjustments to the anilox inventory need to be made to take advantage of ink film thick- ness reduction and opportunities to improve print quality and consistency. • Making an ink adjust to anything else than its own requirements for density and printable viscosity ends up wasting your money on the unneeded ink film thickness. • A proofer is an essential tool of standardization, which requires monitoring of incoming materials and finished inks. FLX_June2010_mech.indd 42 6/10/10 9:39 AM