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FLEXO Magazine : June 2012
Technologies & Techniques Keeping the Heart of the Press Healthy Anilox Roll Maintenance, Care and Handling By steve Wilkinson When I think about anilox roll maintenance, it would be remiss not to include care and handling. These elements are as key to maintaining the perfor- mance and longevity of all anilox rolls and sleeves, as is ba- sic maintenance of these critical components in any modern flexo press. Described by many, including myself, as the “heart of the press,” the anilox roll or sleeve is still sadly neglected. Despite being a constant source of finger pointing whenever there are any print issues, anilox rolls are often disregarded. I can say with some authority — having manufactured anilox rolls in a previous career for more than three decades — most anilox that are returned to the manufacturer for refurbishment are not worn out, but are simply plugged. They are plugged to the point that they are no longer able to consistently transfer a given volume of ink or coating to the printing plate. But, the majority of returned rolls have generally also suffered from significant impact damage, scoring and chipped edges, all caused by improper handling and care by the operator. ANILOX AFFINITY This is not to say that the engraved surfaces of anilox rolls cannot be worn out. In fact, this was the root cause of failure for all earlier copper plated, mechanically engraved and chromed anilox. Although still in use today, the mechani- cally engraved anilox is prone to premature wear and is very susceptible to mechanical damage, even with experienced operators. But, for many coating applications, mechanically engraved rolls are still the ink applicator of choice. There is no doubt the invention of the mechanically engraved surface, dubbed the “anilox,” was one of the crucial points in flexo history. It was this invention that catapulted the process from its lowly status as a cheap and simple print process, to the dominant and grow- ing industry that it is today. But, before I get carried away with the engraved surface of the anilox and many variables, there are other key elements of the anilox that are just as critical to its performance. These include straightness, concentricity, round- ness, dimensional accuracy, rigidity and balance. Any inaccuracies in any of these areas will dramatically undermine the performance of any anilox; whether it is a conventional integral roll or the newer popular sleeved anilox. One should not forget the quality of bearings that are used on the journals of the integral roll or air cylinder that the sleeved anilox is mounted on. These can lead to signifi- cant Total Indicated Runout (TIR) issues if the roll is of poor PRESERVING THE PRESS • Most anilox rolls that are returned to the manufacturer for refurbishment are not worn out, but instead are simply plugged • The majority of returned rolls also suffer from significant impact damage, scoring and chipped edges • The quality of bearings that are used on the journals of the roll or air cylinder that the sleeved anilox is mounted on should not be ignored • On higher speed presses, great care must be taken with larger rolls to ensure that there is no deflection • Minimizing damage to the edge of the anilox can also help reduce scoring of the anilox, which is caused by ceramic particles that break up soda blast cleaning Anilox 92 FLeXO june 2012 www.flexography.org