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FLEXO Magazine : March 2009
TECHNOLOGIES & TECHNIQUES FIGURE 1. 150lpi 2 percent dot over a 900cpi engraving. Process Standardization By Paul Teachout s o, you have completed your Lean initiative. Your value stream has been mapped and you have blitzed every area of your operation. Your shop floor is now a syn- chronized workflow environment pulling production through with more success than ever. Your work centers are standard- ized and everybody knows where everything is. Inventories have been reduced and things are looking up. You now get to go to press with a new order. Everything is in line, the setup begins, everything is prepared and then it takes two hours to match a custom color. What happened? We are Lean; this isn't supposed to happen anymore. I have seen this scenario too many times. The entire operation has been streamlined and standardized but the actual on press process has not. The plate and anilox combination aren't compat- ible. The anilox and ink chemistry don't match up. A process char- acterization has never been completed. This is where the final step comes in. We need to implement a consistent and repeatable standard- ized process to insure first time acceptance. This will create a more consistent flexo process, press to press and plant to plant. As with any new process endeavor, recruit the support of your vendors. There are multiple combinations of consumables and - suppliers. Having their support from the beginning deciding on proper and compatible materials will make this standardiza- tion process go a lot smoother. They will have the experience in overcoming these challenges in many other facilities. Have a roundtable discussion with all involved so there are no hidden surprises. ANI LOX STANDARDIZATION How do we begin overcoming the challenges of on-press pro- cess standardization? Let's start with the heart of the flexo pro- cess. The anilox selection is critical. This will determine the prop- er ink film thickness, solid ink density (SID) and, more important, the proper support for high-line process printing. The two main factors to consider in anilox selection are cpi (cells per inch) and volume (measured in bcm, billion cubic microns). The most effective way to begin the anilox selection process is to perform a banded roll test. A banded roll is an anilox roll that is engraved with multiple bands across its face. Each band will represent an individual cpi and bcm. Photopolymer plate graphics can then be made to align with each band. Each graphic band can be comprised of various LPI values. Results of the printed image can then be quantified and qualified to see which cpi and bcm MARCH 2009 www.flexography.org FLEXO
Sustainable Winter 2009