by clicking the arrows at the side of the page, or by using the toolbar.
by clicking anywhere on the page.
by dragging the page around when zoomed in.
by clicking anywhere on the page when zoomed in.
web sites or send emails by clicking on hyperlinks.
Email this page to a friend
Search this issue
Index - jump to page or section
Archive - view past issues
FLEXO Magazine : June 2012
How did they get here? In my experience, they got what they asked for without any support from the anilox roll supplier to make sure it was what they needed. Or, possibly, they didn’t listen when assistance was offered. A common order mistake from a printer is: “Whatever it was, go ahead and make it the same” – with no questions about a potential better way. Some blame should go to the anilox roll industry in general for the distribution of confusing volume charts that show too many numbers. Engraving charts show minimum, optimum or maximum volumes. Super-size that? This is not a fast food combination meal! Why would I want to see a volume specification from the early 1990s on a current chart? Is there a good reason to show the same volume available at more than six different cell counts? The answer is a resounding “no.” New and improved engravings or cell shapes designed to fix all your printing problems in one fell swoop may not be the answer for every printer either. Anilox related problems are exceeded only by the questions and desire to minimize and eliminate them. Naturally, printers are willing to try anything. Anilox roll specifications can help, but it is still a process that is affected by many variables. As an anilox roll supplier, whenever I have the opportunity to discuss an application with a printer or co-supplier, I listen to what is being asked for. Invariably, it’s a 10- to 15-year-old specification. After asking questions regarding the ink system, metering system the application and the required outcome, I proceed to suggest that what they have asked for may work, but there could be a better way. Consultation with printer’s internal resources and co-sup- pliers insures that every aspect of the process is accounted for when making changes. There has to be a reason to test anything new or different. Print quality and process ef- ficiency are two very good ones. Albert Einstein once said, “Problems cannot be solved by the same level of thinking that created them. ” A common mistake among printers is the simple idea that an anilox roll purchased today will be operational for three to five years; depending on how it is used and cared for. Target current requirements, but consider the future too. For example, a 120 dpi for process printing may be what the customer is ask- ing for on a present process order, however, 133 dpi and then 150 dpi will follow. It is more prudent to put yourself in a proactive position. Being on your own manageable schedule is a better place than reacting to your cus- tomer’s, which is likely to be quite uncomfortable. Is this not realistic? One would be surprised what can happen when you sit down collectively with all suppliers and ask, “Here is where we are now; here is where we want to go; what will it take from each one of you respectively to get us there?” Short of mechanical limitations on existing equipment (which is critical) a firm should be able to achieve its goals. QUESTION TWO Are the anilox roll specification(s) easy to fix? The answer involves benchmark testing. A single anilox roll engraved at an agreed upon volume and cell shape for the print requirement at hand, requires that volume specification comes from printer’s experience; ink supplier’s product knowledge; and anilox roll manufacturer’s engraving and practical experience. Based on test roll performance, the engraving is duplicated or adjusted to meet desired expectations for subsequent roll specifications. Benchmark rolls specified properly work into production inventories after testing. Test plates for benchmark testing contain any and all graphic elements produced on press at the respective volume and should be designed to fail, thus proving print capability of the engraved volume and result- ing ink film thickness. For example, if 133 dpi process dots are the target for current process jobs, 150 dpi and even 175 dpi tonal steps confirm limitations or show increased capability. A banded roll test can also be used to test combinations of ink(s), printing plate(s), mounting tape(s) and doctor blade(s) to optimize those elements on various substrates printed. Designed properly, the specified volumes, on a single anilox roll, fail at both ends with the highest volume provid- ing too much ink and the lowest volume transferring too little. Somewhere in between, all questions are answered pertain- ing to anilox roll specifications for process printing, combina- tions, line work and solid coverage. Goals should be to print with the lowest volume possible re- sulting in the thinnest ink film transferred for the highest qual- ity and most efficient printing. Color is king; therefore solid ink density and Pantone color matches are the targets. LOWER VOLUMES If a volume went from 3.0 to a 2.5 , then it would reduce the anilox volume on press by 17 percent! With that kind of change, a printer can print smaller dots cleaner, smoother vignettes, finer type and run faster with less drying or trapping issues. Not as popular or necessary as in the past, banded roll testing is the most scientific way to optimize your printing process. Banded anilox rolls require more time and planning to test compared to a benchmark roll. These rolls can be expensive, take longer to engrave and, unless future testing is planned, are useless in production. Banded rolls can be reworked to or from existing production rolls that are me- chanically sound. Figure 2 Label, film or carton banded roll layout for process printing, combinations, line work and solid coverage. 60 hex provides ultimate control of ink film for process work. Benefits of 70 hex utilized for combination volumes while the channeling effect of the 30 hex allows the smoothest solid coverage of white, metallic and fluorescent inks and coatings. 102 FLEXO june 2012 www.flexography.org ... continued on page 105.