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FLEXO Magazine : June 2012
Technologies & Techniques Anilox Roll Volume Specifications: Recommendations, Benchmark or Banded Roll Testing? By Dan Foy In a perfect flexo world, one anilox roll specification would do everything. Process printing, vignettes, line work, type, solid coverage and any combination thereof would be executed by one volume and one cell geometry. A scientific printer is always looking to minimize or eliminate variables in the process. To achieve the best print quality and maximize process efficiency, one variable would be a tremendous help—but it is not possible. QUESTION ONE With respect to the anilox roll as a significant variable in the flexographic process, how then do you specify the cor- rect cell volume? Answer: an anilox roll supplier, who offers proactive infor- mation to prevent existing or future issues related to anilox roll engraving specifications, is the go-to source. Whenever I begin a technical presentation on anilox rolls, the first slide after the title is the reminder: “Flexography is a process and is comprised of many elements and variables.” These components include, anilox rolls, inks, mounting tapes, printing plates, substrates, doctor blades, chambered doctor blades, end seals, printing presses, metering rolls, plate cyl- inders, impression cylinders, drying sections, unwind/rewind sections, artwork, prepress, operators, printers and custom- ers. The list could go on to include anything and everything that influences the concept, design, production, inspection and ultimately acceptance by your customers. Despite these challenges, flexography can be a manage- able process when every element is optimized for the printing application(s) required. When we discuss anilox roll specifi- cations, the basic ideas of optimization and standardization are not new. And yet, many flexo printers continue to struggle with inconsistency in color matches and solid ink densities from job to job and run to run. Selecting the correct engrav- ing specifications would be difficult for the vast majority of printers left to their own devices. This is proven over and over through anilox roll inventory inspections which reveal too many volumes, too many cell counts, and simply too many anilox rolls. These printers have too many variables from just one element of the entire process. Printers, operators, helpers or set-up people choose the wrong anilox roll because there are too many choices. This wastes time and materials as well as sacrifices print quality. Conversely, some printers standardize to one specification and wonder, “Why can’t I do more?” TEST, TEST, TEST • Selecting the correct engraving specifications would be difficult for the vast majority of printers left to their own devices • The true value of testing is that everyone involved in a facility, from production to ownership, sees and understands the process better through the planning, running and evaluation of printed samples • While anilox roll specifications can help, it is still a process that is affected by many variables • The best testing is logically planned, conducted, reviewed and acted upon. The more planning that is put into the test, the most efficiently it will run • Printed test samples help your customers see and understand the limitations of the process or the capability you can offer Figure 1 Banded roll outline for combined board printing of corrugated stocks. Three volumes have been engraved at three different cell shapes to see and understand the influence of volume, ink film thickness and cell geometry on various graphic elements from process printing, screens, line work and solid coverage. Channeled engravings at increased cell counts significantly improve solid coverage. 60 hex may not be the answer for all printing requirements. 98 FLeXO june 2012 www.flexography.org Better solids, more control. When you specify anilox rolls featuring the new 70o HV Extended Cell and 60o Hex Cell designs from ARC International, you get more ink control and improved solid coverage without compromising image quality. • With 10% to 15% shallower cells than 60o hex, the 70o HV Extended Cell design means easier, faster press cleanup for less down time • More 70o HV cells per ink volume required give you better solids while reducing pinholes, striations and mottling • Reduces the need for mechanical cleaning Contact your ARC representative to learn how you can profit from applying this cell structure innovation to your operation. 60o Hex Cell 70o HV Cell Anilox Rolls and Sleeves, Plate Cylinders, Impression Cylinders, Wiper Rolls, Doctor Blades, Printing Supplies and Exceptional Service. www.ARCinternational.com 800-526-4569 AR102_1pAdFLXO.indd 1 6/13/12 8:33 AM