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FLEXO Magazine : November 2008
TECHNOLOGIES & TECHNIQUES Where They Started, Where They’ve Been and Flexible Dies Where They’re Going. By Jim Doedderlein T he flexo industry has seen many technological changes over the years in all areas—press technology, anilox tech- nology, substrate, inks, and graphic arts. All have, in some way, improved the quality, makeready and, most importantly, the bottom line of flexographic printing. But, until recently, the con- verting process has always remained the same. The first flexible die was manufactured about 26 years ago. At that time, it was about as crude in form and function as flexo- graphic printing was in the “aniline” days. Since that time, the advancement in technology and various production processes have turned the flexible die into a very viable alternative when compared to the good, old-fashion rotary die. This article will cover those step-by-step advancements in technology and basic safety and maintenance principles of flex- ible dies and magnetic cylinders. EVOLVING FLEXIBLE The first flexible die was, by all accounts, invented and manufactured in the U.S. back in 1982. The technology was very simple in nature and borrowed many processes from the prepress end of offset printing. A file with a specific image was 36 F LEXO created. This file was then sent to a developer, which output a film negative. That film negative was then placed on to a piece of emulsion-coated, tool-grade steel sheet. A vacuum seal UV exposure unit then exposed this piece of tool-grade steel, hardening specific areas open through the film negative. The sheet was then placed through a process that washed away all of the unexposed areas of the steel and what was left was the finished cutting blade. As you can see from the cross sectional view in Figure 1, the resulting blade is weak and will disintegrate shortly after contact with any surface. The next step in the flexible die evolutionary process was the added step of hand sharpening the blades (Figure 2). This certainly helped progress the quality and overall consistency of the die, but defeated two of its greatest potential benefits—lead- time and price. Many converters across the globe have struggled with the tooling lead-time issue, as the tool itself is the one vari- able within the printing process that no one outside of a tooling manufacturer controls. Most printing facilities have their own graphic arts depart- ment, ink department and some kind of onsite inventory of various substrates. The delivery date of the tooling has a ten- NOVEMB E R 20 0 8 www. f l e x o g r a p h y. o r g BEGINNER FLEXOGRAPHER