What’s Your Game Plan?

With flexography, press operators should not rely heavily on the automation of newer systems. “The details and care used in setting systems have become lost in the last 20 years since the introduction of ceramic anilox rolls that are more forgiving and allow for automated chamber systems that often have extra pressure to keep ink from leaking through end seals,” says Jean Jackson, technical account manager, Allison Systems. “This extra pressure is leading to flatter doctor blade contact angles that, on the newer high speed presses or with higher viscosity materials like UV, become even lower during the pressrun.” Most modern flexo presses are automatically aligned to 30-35 degrees, and if the chamber is not over-pressured, that is where blades should remain. When the angle decreases, dot gain will be the first sign of excess pressure, says Stamey. “Sending a set of used doctor blades to the blade supplier for angle analysis will determine if [too much pressure] is the cause of the problem,” he suggests. But, Norm Davister, senior sales engineer, Printco Industries, says, “Even if the doctor blade angle is set correctly by the equipment supplier, varying degrees of printing imperfections will result with the slightest blade angle changes caused by overloading the system, [which is] usually seen when the doctor blade has been worn beyond the intended life span. The doctor blade should be replaced at this point rather than adding extra blade pressure.”