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FLEXO Magazine : May 2012
Plants & Processes Substrate & Ink Metering the Key Determiner of Flexographic Press configuration By Kern cox Look at the environment around you. How much print is around you right now? What is unique and eye catch- ing about it? Hundreds of times a day, printing influ- ences everyone’s life; from the labels on the products, to the packaging food comes in, to the signage. People outside the printing world might look at printing and only see a message intended by the brand. Meanwhile, consumers might only feel an emotion from the color scheme or the words used. Folks inside the printing world see products and reflect emotionally on the technical challenges to achieve quality printing. Industry insiders see a printed piece and inspect how the halftone screens are printed, what the ink sequence is, how much impression is used and how good the registra- tion is. Additionally, they might look to see if the printing pro- cess used is recognizable and what challenges the substrate posed for the printing process. It has long been known that substrates are the backbone of quality printing. It is the baseline for color fidelity and crisp images. How well a press is tooled to a specific sub- strate determines how much of that graphic potential can be achieved from that substrate. If a press prints many different substrates, then a unique set of tooling and process deci- sions are needed for each. This poses a challenge because it decreases production efficiency. The purpose of this article is to address the ins and outs of ink metering decisions for the flexographic process based on substrates. SUBSTRATE SURVEILLANCE • Substrate choice is an economical decision. A pack- age must fit within a marketable cost model while delivering on performance • The better the surface and the more stable the sub- strate, the better the print. A fundamental purpose of any ink metering system is to deliver a uniform ink film thickness to an image carrier • The method ink is applied to, and then metered off the anilox roll, plays a major role in consistency • Ink metering configurations require constant testing and adjusting for optimal results Figure 1: Basic components of an ink metering system for flexography. this diagram illustrates both the two-roll system and two-roll system with reverse angle doctor blade. Figure 2: Diagram of a chamber blade ink metering system. 48 FLEXO may 2012 www.flexography.org Fountain Roller Anilox Roller Doctor Blade Plate Cylinder Impression Cylinder ink Pan Print Web Anilox Roller Plate Cylinder Impression Cylinder Ink Chamber Pump Print Web Doctor Blade Containment Blade