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FLEXO Magazine : March 2010
30 FLEXO MARCH 2010 www.flexography.org • Ceramic is inherently porous, which allows migration of whatever it comes into contact with. This empha- sizes the importance of the barrier coat layer to protect the base aluminum. • The bond coat prevents separation of the ceramic from the aluminum and protects the soft metal from corrosion. Inks, manual cleaners, on-press auto-wash cleaners and off-press cleaners must be used under strict guidelines in this environment. • The future of anilox sleeves likely lies in a hollow sleeve with a composite carbon fiber outer tube and hubs that "slide" on the mandrels without an expan- sion layer. Understanding Your Anilox Sleeve Three Ways of Looking at Proper Care While the anilox sleeve looks simple, it is actually a rather complex design. It is made up of several layers, including the base sleeve, a cushion layer, and the ceramic coating, which itself is finely engraved with all those tiny cells so necessary to its function. This makes proper clean- ing, care, handling and storage critical. Understanding all the components, how they interact and common problems that can arise from poor practices will ensure the longest possible life and optimum functioning of the anilox sleeve. What follows is a three-pronged perspective from an anilox engraver, an anilox cleaner, and a sleeve manufacturer. CLEANING AND HANDLING From the perspective of the anilox engraver, the pressroom anilox program for the care, cleaning, and handling of the anilox tool is very crucial to the performance of the roll in the press. The engraver must fully understand the pressroom's anilox processing conditions to ensure the roll or sleeve engraving is processed correctly to perform within the speci- fied environment. These conditions include understanding the print process, type of inks or coating applied, handling methods, cleaning methods, and general housekeeping pro- cedures for the anilox. The engraving process entails adding value to a tool sup- plied by the tool supply fabricator. In today 's flexographic market, there is a higher trend toward selecting anilox sleeves based upon efficient handling and changeover speed. These sleeves are fabricated from aluminum, which needs protection from corrosive applications. The engraver must understand the press applications to ensure the proper barrier coat is applied to protect this aluminum base. Of course, the more corrosive environment, the higher the level of barrier protection required, in turn equating to higher processing costs. The ceramic layer is added on top of the barrier coat as the medium for laser engraving. This ceramic is known for being very hard and having a long life in regards to wear. However, ceramic also is inherently porous, which allows migration of whatever it comes into contact with. This again emphasizes the importance of the barrier coat layer to protect the base aluminum. The integral steel base also requires barrier protection according to application, although steel is not as vulnerable as aluminum The pressroom must also determine the best anilox clean- ing method for the application. With today's more environ- mentally friendly ink systems and the processing abilities for much higher print quality, it is imperative for the operator to continually monitor its anilox cleaning process. The laser en- graver can now supply high-definition anilox rolls, which have cell structures that require more attentive cleaning after the print process. With proper cleaning, the anilox will perform to specification on install and minimize press setup time. The care and handling of the anilox is essential to the engraving print performance and life span of the tool. It is a fact that most rework engravings come from contact damage or some form of mishandling of the engraving tool. A properly documented and executed anilox program will ensure print quality and minimize future rework costs. Contact your pre- ferred engraver for the details and presentations to assist and educate your press crew with a proper anilox program. ---David Skellie, president, Interflex Laser Engravers SLEEVE CARE Gradually, printers/converters are replacing their older generation presses with anilox journals in favor of sleeved presses. Anilox sleeves are lighter, easier to remove from the press, and easier to handle. These anilox sleeves have been manufactured using various thicknesses of carbon fiber, aluminum, and other metals cores with bladders or mechani- cal configurations for ease of mounting and demounting to and from the mandrel. Anilox sleeves have now been in the marketplace long enough for OEMs and end users alike to better understand how to manufacture, clean, handle and store these anilox sleeves. Aluminum is the metal of choice because of its relative strength in relation to its light weight. It is a smooth and less porous metal than stainless steel, which is used for journaled rolls. Because of these characteristics, sleeve manufacturers are continuing to experiment with various types and bond coat thicknesses between the aluminum and ceramic. This bond coat prevents separation of the ceramic from the alumi- num and protects the soft metal from corrosion. Inks, manual cleaners, on-press auto-wash cleaners and off-press cleaners must be used under strict guidelines in this environment. The development of anilox sleeves and cutting-edge en- graving technologies have created much higher line screen counts and deeper cells with higher volumes. These innova- tions have created challenges that require converters to use "on press" automated wash up systems, manual hand clean- ers and off press automated equipment cleaners under the guidelines provided by each supplier and should be read and understood. Even ink and water by themselves are corrosives! All of these methods and systems can be very effective in cleaning sleeves, if used according to instructions and in the correct environment. TECHNOLOGIES & TECHNIQUES
Sustainable Winter 2010