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FLEXO Magazine : November 2012
External to the press, you would consider a secondary cleaning system like, media or soda blast, ultrasonic, soak tank, dishwasher type or laser. While there are a variety of systems to choose from, the most important point about any of them is keeping them maintained to the OEM specifications. Equipment works best when operated under proper condi- tions of air pressure, exposure time, temperature, rotation and media type/specification. When the systems are not maintained, the cells won’t get cleaned and under extreme settings/conditions they can also become damaged. Anilox maintenance has both internal and external functions. Internally, an operator would be expected to be responsible for the physical location of the anilox, including roll protection. Bearings and gears need to be maintained and checked for any signs of failure; before aniloxs suffer as a result. Externally, maintain a supply of gears and bearings that meet specifica- tions. Anilox selection becomes a simple process for the opera- tor in a standardized setting. Aniloxs should be defined from a job setup and from external selection processes. Using a planned experiment featuring a banded roll or using a qualified recommendation, standardization of anilox specifications can reduce the variation found in uncontrolled inventories and narrow down to just a process, line/combo and then what is needed for specialty applications like metal- lic, opaque white, fluorescents, adhesives. Based on all this background work, operators should then be able to answer three simple questions when looking at an anilox: 1. What is it? 2. Where does it go? 3. Is it ready to be used? Anilox verification is something that an operator can quick- ly do with a simple scope system. Once an anilox is cleaned at press, perform a quick examination for damage and cell cleanliness. This simple step avoids lengthy delays in press. Externally, once a roll has made it out of a secondary clean- ing system, more sophisticated inspection systems can be used to recertify rolls. These systems need to be calibrated to be an effective measurement of anilox condition. Alternatively, aniloxs can be audited periodically by the anilox suppler. The benefits of an audit include a fresh set of eyes to detect problems early, which often saves the bulk of the inventory from damage by raising awareness. After the cleaning and verification, certify the rolls through a tagging system that makes identification simple. Also, flag potential issues associ- ated with using an anilox with a minor flaw. PLATE MOUNTING FUNCTIONS As plates and mounting relate to the operator, there are three items he or she can attend to. He/she must be able to clean the plate properly without causing plate lift, install with- out damaging and maintain the physical condition. Externally, there are many pitfalls that must be avoided and can be addressed with a thorough inspection process. It be- gins by having the entire plate inspected for cracks, wrinkles, lost images or underdeveloped images. Lost images would include targets that have been removed for whatever reason. Remember that without measurable targets, the operator cannot measure and control and will be forced to make blind adjustments and tinker. Utilize tools like pads, brushes and sponges for plate cleaning, both for the image surface to avoid print defects and the back of the plate to remove residue interfering with adhesion to the mounting tape. Tape selection should already be defined by the fingerprint. Mounting hardware should have an undamaged surface as those defects will otherwise translate to the print. Cylinder and mandrel accuracy must also be checked. Follow OEM protocols when designing best practices for these components. Any platemounting equipment must be up to par. Compo- nents like bearings, locking head position, camera position must be evaluated and mechanical play must be eliminated. PRINT SAMPLES When an operator is provided a printed sample to match, he/she is faced with a very difficult situation. Operators can only match within the realm of specification determined by process and press capability and print samples may fall well outside those parameters. Internally, all one can ask an operator to do is maintain the sample, look at it under the appropriate light source and measure when possible to verify a match. Often, the samples will run afoul of press capability because the sample was not originally run to some standardized format. Externally, determining the true specification and communi- cating amongst all parties is essential to provide an opera- tor with the needed target. Age of the sample and substrate condition affect the color perception and must be taken into account. Illumination is a standard that must be established between customer and printer. Illumination often reveals All inks can be compromised due to temperature extremes or contamination. The external ink process must deal with three main issues; ink selection, color match and then storage. Specific selections should be determined in a lab through testing. 42 FLEXO november 2012 www.flexography.org