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FLEXO Magazine : June 2012
to have one of the newer scopes that can measure the rolls on the spot, but often budgets restrict those purchases. In a large pressroom, with hundreds of thousands of dollars invested in anilox, these tools might make economic sense. There are other tools that I use everyday and are always with me: a good handheld microscope, or one of the new micro- scope units that can attach to an iPhone or computer. These tools provide a visual image of the engraving that can help indi- cate if the roll is worn and or dirty. While it won’t give a number, it can show an image that you can compare against the anilox supplier’s engraving certification picture provided with the roll. The magnification will need to be high enough to get about a dozen cells in the image, so between a 200x and 400x magni- fication is required. Also, having some microfax materials for the questionable conditions, that can be sent to your anilox supplier for assessment, will give you current information. After a pressrun and cleaning, capturing notes of the visual condition of the roll is critical. Pulling a damaged roll from inventory to find lines and dark or light print areas is a waste of time. These issues could be avoided by a quick visual inspection after roll cleaning. Look for lines, either scorelines or pickup lines, as they will often print either a dark or light line in the job and often right in a critical image area. If these defects are detected, discuss it with the anilox and/or blade suppliers to understand the cause of the damage. Additional care and maintenance training, as well as developing a stan- dard program will pay dividends, when used daily. When looking at cells under a microscope, wider cell walls can indicate wear or material pickup on the surface that is not being removed in the cleaning process. Color or a puddle of material in the bottom of the cell indicates that ink is still in the cell. Many rolls, thought to be worn out, are often just dirty as the cleaning sys- tem isn’t getting the cells clean. Work with your suppliers to get a cleaner that works on your ink system and anilox roll. Also, remember to rinse the roll well after cleaning as to not leave any cleaner in the cells. These agents can interact negatively on the next pressrun. The engraving is probably still dirty if color can be seen on the roll face. INSTRUMENTATION There are challenges in anilox measurement because we no longer have uniform pyramid or geometric shaped cells that use a gravurescope to measure linear dimensions and calculate volumes. These challenges include the curved cell shapes with infinite screen volume combinations and no Ameri- can National Standards Institute (ANSI) standard for this type of measurements. The industry is addressing and redefining these issues. The recent Flexographic Technical Association (FTA) Flexographic Quality Consortium (FQC) anilox roll gauge study of closed cell structures looked at six current measure- ment methods, from interferometry to advance microscopes to liquid volumes. All of the methods were developed as the result of an industry need. The FQC continues to improve on address- ing the expansion into open cell structures — the next FQC anilox gauge project. The instruments are very capable and repeatable but there is no ANSI standard to calibrate against. Because of the lack of standards, each instrument may have a different reading for the same roll’s engraving. Building a correlation or cali- brating to the supplier’s measurements can be very helpful, when different instruments, made by multiple manufactur- ers are used to measure the ingraving. This can be done by regularly measuring the new engravings upon receipt and collecting data from a range of engraving volumes and line counts. Also, it is important to be aware of the tolerances on the measurement device. To better manage the print process, remember that the anilox roll is the heart of the process and requires understand- ing and care. In my 30 years in print, most of the anilox chal- lenges have been the basics that need to be applied. Getting an understanding of your ink metering system with the anilox roll, ink and blade suppliers involved will help the anilox roll be the precision tool it is designed to be. Better management of the anilox inventory will quickly pay back dollars with more press uptime and consistent, repeatable print. This translates into happier customers and better profitability. n About the Author: Jean M. Jackson is Sales Manager, NA Print- ing, Praxair Surface Technologies Inc. She is a member of Flexographic Technical Association’s Hall of Fame, inducted in 2007. This year, Jacskson completed two terms of service on FTA’s Board of Directors and its Foundation’s Board of Trustees and she also co-chaired the FOG’D Session at Forum 2012. Her involvement with FQC extends back to 1994, and her commitment and contributions to FIRST’s continued develop- ment align with that program’s inception. Jean co-chaired the 2003 FIRST Conference. She has also been a fixture on the Ex- cellence in Flexography Awards Committee or judging teams for 15 years. Her resume of service earned her the 2003 FTA FFTA President’s Award. Example of dirty cells Press Side Standard Operating Conditions: FIRST Sample 86 FLEXO junE 2012 www.flexography.org C:\Documents and Settings\idyewlc1\My Documents\marketing communications\printing\Layout Files\P10341_novaline_series_datasheet.indd April 16, 2010 1:35 PM page 1 NovalineTM Series Laser Engravings for Anilox Rolls. Digital precision engravings for demanding flexo printing applications. New!NovalineTMSeries Novaline engravings are a new series of open-cell engravings that build upon Praxair’s open- structure engraving breakthrough with the introduction of our ARTTM and REVTM engravings more than 10 years ago. The Novaline Series of engravings utilize the latest laser technology where the laser beam is deflected and modulated at high speed to create a digital description of each cell. Novaline Advantages • Precise and digital control of the cell shape ensure unsurpassed repeatability and reproducibility of all engravings • Smooth cell surface produces better ink transfer from cell and improved cleaning • Increased wear resistance due to re-melt effect of ceramic • Smoother and more regular side walls ensure optimal contact with doctor blades thus reducing probability of score lines • Much higher opening-to-depth ratio compared to conventional 60-degree engravings • Improved ink release / cell cleaning and reduced probability of ghosting effects • Maximum achievable volumes increased by 20% to 40% for a given screen count depending on Novaline Series engraving • Allows for an increased anilox line count for a given volume transferred on the substrate improving print resolution without compromising print quality Multipurpose applications High-quality applications Flexible Packaging Paper Packaging Corrugated Labels Offset, Varnish NovaTM Silver Engraving NovaTM Gold Engraving ARTTM Gold Engraving UVTM Gold Engraving ARTTM Gold Engraving UVTM Gold Engraving Calibrate the X-rite once a day! Read Density with the DOT function! Press Characterized November 16th, 2005 Process Color Only! C1S Coated, Flint Ink, 150 lpi, 900 fpm Color Sticky Back Anilox Relative Density 50% 30% 5% 1% Black 3M1020 #23 1,000/2.60 1.55 -1.65 84-88 64-68 22-25 14-16 Cyan 3M1020 #27 1,000/1.20 1.50-1.60 72 -76 50-54 14-17 4 -6 Magenta 3M1020 #41 1,000/1.28 1.20-1.30 64-68 46-50 15-18 4-6 Yellow 3M1020 #40 1,000/1.07 1.90 -1.00 74 -78 50-54 12-15 4-6 Mohawk Matte, Flint Ink, 150 lpi, 900 fpm Color Sticky Back Anilox Relative Density 50% 30% 5% 1% Black 3M1020 #4 800/3.4 1.40-1.50 82-86 60 -64 22-25 14 -16 Cyan 3M1920 #30 800/1.9 1.30 -1.40 70-74 52-56 18-21 5 -7 Magenta 3M 1920 #42 800 / 1.9 1.20-1.30 68 -72 48-52 17-20 10-12 Yellow 3M 1020 #38 800 / 1.9 .95-1.05 72-76 52-56 18-21 4 -6 Matte Target X-Rite Specifications for the Cerutti Dot Area % C1S Dot Area %