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FLEXO Magazine : August 2013
Foundation of Flexographic Technical Association Technical Education Services Team 3920 Veterans Memorial Hwy Ste 9 Bohemia NY 11716-1074 Phone: (631) 737-6020 Fax: (631) 737-6813 www.flexography.org FLEXOGRAPHYPrinciplesandPractices6.0 Balancing Flexographic Rollers An Excerpt from Flexography: Principles & Practices 6.0 Increases in printing speeds and quality standards, preva- lent in the flexographic printing industry today, make it nec- essary to consider the importance of accurately balancing the various rollers and cylinders used in the press. Balancing is a process, whereby the distribution of mass in a roller is altered to eliminate vibration at the supporting bearings. A roller can be manufactured to very close dimensional tolerances and can be properly designed structurally, so that it is a rigid integral unit in a static state. Sometimes, however, in spite of all the care and precautions taken, the press in which the roller functions does not perform satisfactorily. Gen- erally, this is due to excessive vibration. In the case of plate cylinders, the addition of the plate mass itself, may cause imbalance vibrations. These vibrations often limit the printing speeds the press is mechanically capable of producing. The cause of imbalance in rollers, although usually obvi- ous, is frequently overlooked. Imbalance is caused by the lack of homogeneity in a material, whether it is casted, forged, extruded, or otherwise produced. In the case of tubular or cylindrical products, an uneven wall section can cause imbalance. Evidence such as blowholes, slag occlusions, and variations in the crystalline and chemical structure of a mate- BAD VIBRATIONS Problems that are a direct result of vibrations produced by unbalanced cylinders include: • Excessive printing plate wear • Excessive bearing wear • Excessive roller wear • Reduction of the overall mechanical efficiency of the printing unit, such as uneven impressions • Associated resonant vibration of other parts of the press or its supporting structure • Possible failure of structural components of the press • Excessive noise created as a side effect, which often reduces efficiency of the pressmen 36 FLEXO August 2013 www.flexography.org FTA TODAY Press Buyer’s Guide