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FLEXO Magazine : June 2013
Technologies & Techniques Don’t Just Go with the Flow—Control It! Automated ink Regulating, Cleaning Methods Prove Fast & Reliable By Henrik Kristensen Uniform, smooth and uncontaminated laydown of flexographic inks and coatings is an essential factor in ensuring print quality. To achieve this, constant control of the flow, viscosity and temperature of the ink must be main- tained between the dispensed bucket and the anilox roll. Ink or coating must be at the right viscosity in order to achieve the optimum dot gain values. Maintaining constant temperature, of particular concern on longer runs, is necessary to avoid evaporation and viscosity deviations. Optimum pres- sure is needed to ensure ink or coating is free of air bubbles in the chamber and when it is carried to the anilox cells. Managing the ink or coating supply has become a press- ing concern because the faster speeds possible on the latest presses – up to 500 m/min – can increase the risk of foaming, trapped air or deviation in density, resulting in quality loss. Monitoring the ink flow manually is undesirable because it is an intensive, time-consuming task that demands constant attention of the press operator. Furthermore, the closed architecture of central impression presses makes interven- CHAMBER BLADE BENEFITS • Maintaining constant temperature is necessary to avoid evaporation and viscosity deviations • Optimum pressure is needed to ensure ink or coating is free of air bubbles in the chamber and when carried to the anilox cells • Since closed architecture of central impression presses makes intervention difficult, automated ink control and optimized cleaning methods are favored because of their speed and reliability • The dual doctor blade’s ability to meter the ink makes the fountain roller redundant • Ability to achieve consistent ink laydowns allows improvement of ink yields by up to a fifth compared with double-roller alternatives • Leftover ink can be stored for long periods, without evaporation or perishing solvent ink supply system ensures safe, pressure- controlled ink circulation, especially in Ci flexo printing environments. 86 FLeXO June 2013 www.flexography.org