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FLEXO Magazine : June 2014
Flexo - Mastering the great juggling act... Apex offers you the anilox solution! Our customers mentioned these benefits: UltracellEXT GTT Ultracell Diamant Maximized printability! Simplified standardization. Higher consistency. More profitability. You choose GTT for predictable printing of stronger and cleaner type, reverses, barcodes and dots. You can print repeat jobs at the same high quality with minimal adjustment. See if GTT can give you that advantage, time after time, job after job. CONVENTIONAL ANILOX. UNCONVENTIONALQUALITY. ® THE FUTURE OF FLEXO ® ®ACCURATE, DURABLE & NEW APEX NORTH AMERICA Tel: 724 379 8880 www.apex-groupofcompanies.com email@example.com APEX FRANCE +33(0)475463942 fr ance @ap ex - eu rope. com t e APEX EUROPE +31(0)497361111 firstname.lastname@example.org t e APEX DEUTSCHLAND +49 (0) 2823 929 360 info@ apex - d eutschland .de t e APEX ITALY +39 (0) 331 379 063 email@example.com t e APEX IBERĺCA +34 (0) 93 583 1012 firstname.lastname@example.org t e APEX ASIA +65 (0) 6284 7606 email@example.com t e APEX LATIN AMERICA +55 (0) 41 3677 2678 firstname.lastname@example.org t e What can we engrave for you today? USE, CARE AND MAINTENANCE ADVICE Visit us! Visit us! Stand 5610 Stand 5610 away from the blade or accumulate on its back side. Any ink that collects on the back of the doctor blade will build up and eventually flow off of the blade and ultimately transfer to the web. FQC UV INK DISCUSSION The Flexo Quality Consortium (FQC) as- sembled a team of experts from various fields relevant to the flexo process to explore the problem of UV ink spitting. Their findings were assembled by Sean Teufler from Harper Graphic Solutions and published in the Feb- ruary 2012 issue of FLEXO® magazine. The findings of the FQC team were not conclu- sive, due to the unpredictable nature of the problem, but some interesting points were presented that are worthy of repeating. The chart shown in Image 2 was presented by Sean as a summary of various factors that contribute to spitting. The chart lists the various elements studied and an “up charge” value was assigned to each element. An up charge value greater than zero indicates a larger potential for the element to contribute to spitting and the larger the value, the great- er the potential. The chart as presented shows the elements with the greatest potential to contribute to spitting in dark blue. Let’s examine the chart and interpret what it is indicating for some of the categories spe- cifically related to the doctor blade. One of the elements considered is the operator, with two categories of “harsh” and “not harsh.” It is not surprising that a harsh operator is more likely to cause problems. But what is meant by a “harsh operator”? One could expect a harsh operator would be someone who applies excess doctor blade pressure, has poor housekeeping and setup habits as related to doctor blade installation and blade to anilox alignment. In general, all of these practices are detrimental to doctor blade performance but are particularly troublesome for UV ink performance. Another element compared the contribution of blade material to spitting issues. Trials indicated that typical carbon steel doctor blade materials were more likely to spit than the higher quality, long life tool steel material. Carbon steel doctor blades will wear faster than a tool steel blade. As the blade wears, JUNE 2014 | FLEXO 63 “Generally accepted doctor blade contact angles for flexographic printing will fall into the range of 25 degrees to 42 degrees with a desirable angle being near 30 degrees. Testing has shown that for UV inks, the contact angles should be at least 30 degrees or more to minimize UV spitting issues. ”