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FLEXO Magazine : February 2010
24 FLEXO FEBRUARY 2010 www.flexography.org TECHNOLOGIES & TECHNIQUES • The HVP anilox roll uses an engraving technique that produces an elongated cell that actually results in two different line-screen counts. • Expanded gamut sets use between six and eight colors, so the angle of anilox engraving has to move away from the traditional 60 degree in order not to clash with the printing plate. • A corrugated printer can utilize a HVP 360lpi, 7.5bcm2 roll, improve his printing, and not have to worry about cells plugging. Over the past several decades, the standard anilox roll cell configuration has been based around a hexago- nal cell formation, engraved at a 60° angle. With the advancement of digital plate technology, flexographic printers have been longing for advanced cell technology to allow them to reach better print quality levels with higher definition im- ages, while maintaining corporate branded color consistency, lower dot gain and increased ink transfer. To enable printers to reach these goals, Pamarco Global Graphics has developed a high-volume pigment (HPV) anilox technology, which it calls E-FLO. The HVP anilox has been developed specifically for the flexible packaging and narrow web marketplace. However, it also adds tremendous advantages to the corrugated markets, specifically when looking to print a combination of screens and solids or a good overall solid coverage eliminating skip feeds. Printers rely on their suppliers to develop new technologies to assist them in satisfying their customer's needs. Cur- rent anilox technology uses solid-state, fiber optic lasers to engrave anilox cells. Fiber optic technology allows cells to be engraved with multiple pulses from the laser, which produce a flatter bottom and the ability to get more cell depth per line screen. Printers can utilize engravings consisting of higher line screens and cell volume than has been possible in past years. This technology helps to achieve high ink densities, low dot gain and clean type. Fiber optic hexagonal screening technology has been pushed to its limits. THE LONG AND SHORT OF IT The HVP anilox roll uses an engraving technique that pro- duces an elongated cell that actually results in two different line-screen counts. The number of cell walls vertically around the anilox is 60 percent of the number of cell walls in the horizontal direction. The bottom is elongated, which makes it easier to transfer ink and re-fill the cell with fresh ink. Because of the elongation, the cells stay cleaner and transfer a higher percentage of ink, consistently. Due to this unique shape, printers can specify a horizontal line screen that is up to 40 percent higher than their current line screen at a 60° angle, with volumes that are the same or even higher. The unique cell shape allows the ink to release more fluently increasing the amount of ink volume transferred onto the substrate, improving the overall density and opacity levels. This has been a par- ticular benefit for whites print- ing on clear film. This ability to use a higher line screen without sacrificing density allows for a higher dot support, especially with digital plate dots that are much more fragile than analog dots due to their profile, conventional 60° rolls can cause dot plugging into the anilox causing the finer dots to break off producing scabby print. The HVP anilox's cell shape enables cleaner print, with the ability to achieve higher ink density with- out any dots breaking away at dots of 1 percent and below. The new cell formations have been developed in conjunc- tion with newer ceramic coating technology that is much more durable. This new coating technology is critical when producing the HVP engraving. It works with the cell technol- ogy to provide a much more stable cell wall, not allowing the walls to break up, which contributes to scoring. Combining these two technologies allows for faster press speeds with less wear and a higher resistance to doctor blade scoring. HVP anilox technology is a unique cell structure and com- bined with a new improved cell angle profile that will provide a more consistent and increased ink lay down. This unique cell angle profile now allows printers to work with expanded color gamuts, with no concern of loss of color density or the anilox angle clashing with the printing plate. Traditional CMYK sets use four dot angles with an anilox of 60°. Expand- ed gamut sets use between six and eight colors, so the angle of anilox engraving has to move away from the traditional 60 degree in order not to clash with the printing plate. As buyers of printing and packaging materials continue to demand higher quality print on a variety of substrates, print- ers are now requesting their plate suppliers to provide higher line screen plates (200lpi) along with new screening technolo- High Volume Pigment (HVP) Engravings The Next Advancement in Anilox Technology By Dave McBeth and John Bingham An elongated cell shape allows HVP (high volume pigment) engraved anilox rolls to deliver more ink to the plate.