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FLEXO Magazine : March 2011
Technologies & Techniques Optimizing Pumping Systems for the Press How to improve quality, Control Costs & speed Changeover By Craig shields One of the questions that builders and operators of flexographic and gravure printing presses should ask—but rarely do—is how to optimize the pumping systems for their presses. A well-designed system improves print quality, lowers lifetime cost and provides rapid change- over between runs. The payback for taking the time to think through your pumping system carefully can be immense. When considering the inking system, everything is a tradeoff, typically between time, operating costs and costs up front. Think hard about your company ’s niche and what you are trying to accomplish on press. Are you doing long runs? Short runs? Rapid changeover? Common colors and coatings? Do you care more about the cost up front or what your costs month- to-month might be? All of these questions come into play when select- ing an inking system and should be discussed with your vendors. PumP Or NO PumP? Although pumps are important, some presses come without them. Eliminating the pump lowers the cost of the press, which is especially important on lower-end presses. Also, not having a pump simplifies the inking system, espe- cially on very short runs. However, in general, pumps should be used for several reasons. First, they allow the use of chambers. With modern doctor blade systems, a pump is essential for feeding ink into the anilox. Second, they foster operator efficiency because the ink reservoir can be sized for the job, thus eliminating the need for the operator to check the ink level continually at each deck. This also minimizes the chance of starvation. Third, pumps provide consistency. Ink—especially water- and solvent-based ink—needs to be mixed continuously to main- tain operating viscosity and keep the pigments mixed. Without the circulation provided by a pump, the ink can stagnate in Pumps & Performance • Centrifugal, peristaltic and diaphragm pumps each have benefits and weaknesses. • Pump size dictates the pressure and flow achievable. • Three motor choices apply to printing—air/pneumat- ic, electric and explosion-proof electric. • Round and oval tanks allow better mixing of the ink. • Poor fittings have the ability to destroy the perfor- mance of an otherwise well-planned system. 32 FLeXO marCH 2011 www.flexography.org FLX_March11.indd 32 3/18/11 1:32 PM