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FLEXO Magazine : July 2007
w w w . f l e x o g r a p h y . o r g J U LY 2 0 0 7 F L E X O 4 5 gLObaL markets IndustrIal skIlls traInIng Recent experience of attempting to improve efficiency with flexo printers has often highlighted the need to improve print- ing skills. For many years, the EFTA has had several skills-based training initiatives in place. The most prevalent are the distance- learning capabilities offered by the FACE (flexography accredited computer education) CD program—a series of technical training programs that are directed at specific production skills/knowl- edge. The FACE CD program can be used as a standalone dis- tance-learning, computer-based learning/teaching tool, and both member companies and private individuals can purchase the series of CDs. Public training sessions are regularly organized with the ob- jective of improving production skills/knowledge in a group environment. These are practical (hands on) and are held at the national printing skills center in Leicester. The two-day courses are graded into three levels set currently at introduction, interme- diate, and advanced. Once a year, EFTA runs a “Master Class” for all candidates who have previously attended the advanced-level course of the basic skills training. The “Master Class” is a two-day event designed to facilitate the candidate making a complete packaging job—from the basic design brief through to the final printing stage. The “Team Challenge” is training to facilitate the migration of suitably qualified candidates from daily production to junior management. The training takes the form of specific companies sending teams entered into the yearly challenge to a designated hotel for one day, including an overnight stay. The candidates are sent a task for which they have to provide the most innovative and imaginative technical solution. During the day, adjudicators assess the solutions provided by each team. A spokesman is appointed and a presentation is made to the adjudicating panel comprised of industry experts. Individual contributions are assessed throughout the day, and the relevant management training points are highlighted to the teams and individual team members during the end of session debrief. underpInnIng scIence explaIned For many years, EFTA has supported the research of the funda- mental science upon which our flexographic process is based. Dr. Tim Claypole leads the research team of more than 20 people at the Welsh Centre for Printing and Coating (WCPC) based in the School of Engineering, University of Wales Swansea. The center’s activities are focused on fundamental flexographic scientific re- search and its translation (with simple explanation) into the print- ing industry. One of the frequently asked questions by flexographic industry practitioners is, “Do the researchers know which questions to ask?” This question is often asked out of naivety. The flexographic process is shown in diagrammatical form in Figure 1, and the correct question that is posed by the schematic is, “Do the re- searchers have the answers?” The obvious response is, “Not yet,” but that is part of the ongoing fundamental research that is being undertaken on a daily basis by WCPC. FIgure 1.+#3; Schematic of the flexographic process. FIgure 2.+#3; Graph of ink density versus viscosity. FIgure 3.+#3; White-light interferometry plots on an inked anilox roller. FIgure 4.+#3; Pressure versus ink release graph. Another simple question the printer should ask is, “Is solvent added to the ink to control the viscosity or is it added to change the color strength?” The four different inks shown in the graph in Figure 2 have different pigment concentrations, so to achieve the same color, four different solvent concentrations have to be added. Anilox Cells 1. Dot engaged with anilox cells 2 Ink pulled from cells 4. Ink split between plate and substrate Deformation Substrate Ink Spreading 3. Dot engaged with substrate 2.5 2 1.5 1 0.5 0 % of neat Ink 0 5 10 15 20 25 30 35 40 45 50 55 d en si ty Ink A Ink B Ink C Ink D 60 50 40 30 10 0 Anilox 1 In k re le a se ( % ) 20 Anilox 2 Anilox 3 Pressure 1 Pressure 2 Pressure 3 How much ink transfers from the anilox roller to the plate? Bottom of the cell After inking the roller land areas are showing through After inking a solid all of the ink is not removed from the cell Land area is not
Golden Anniversary Commemorative Journal