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FLEXO Magazine : August 2009
TECHNOLOGIES & TECHNIQUES Like the evolution from typewriters to the fi rst computers to today’s technology, fl exo press motors have evolved to be faster, more effi cient and more cost effective. A step up from the simple press motion control system mentioned above is to add one servo motor to drive the print head instead of a gearbox. This press design is often referred to as a hybrid or shaftless design—part mechanical and part electronic motion control. Again, this improves upon the geared and simple servo press design, but still has geared cylinders that can limit the effi ciency. More advanced gearless-shaftless systems incorporate an electronic motion control system that drives each plate and impression cylinder independently (eliminating the mechanical interference in the print train) and the infeed and outfeed of the press. This provides for very precise synchronization of all printing and drive elements in the printing press. Benefi ts to this type of design include precise web transport, exceptional print registration and stability and greatly enhanced repeatability. In effect, this type of motion control system provides much more “science” in the production process compared, to the “art” involved in a geared printing press production process. By digitally controlling the web tension, pre-register and register positioning, many of the setup characteristics are automated and easily repeated on future production runs. To further enhance this system, the die stations can be driven with servo motors for improved registration in the in-line fi nishing process. Leading press designs utilize a very sophisticated integrated direct-drive motion control technology that eliminates all mechanical interference (lineshafts, gears and gear reduction units) in the press by directly driving each shaft. This requires a press manufacturer to have a wealth of electronic engineering expertise and experience in-house. The benefi ts of this technology are exceptional stability, registration and effi ciency. This is done by electronically controlling (directly) most or all of the axes in the press including plate roll, impression roll, chill drum, infeed, outfeed, die stations, nips and inline attachments such as cold foil, hot foil, laminations, etc…). This very sophisticated type of motion control press design will provide a more stable and repeatable performance that greatly exceeds the other designs with much less waste! COST VS. PERFORMANCE The question now becomes, what is cost effective? Typically, as we add more electronic control to the printing/ converting process, we add more cost and complexity. The key is in fi nding the correct balance that still provides all the production process benefi ts that leading motion control designs can provide, yet maintain a cost-competitive solution. The engineering world has coined a term for this: mechatronics. Mechatronics is the synergistic combination of mechanical engineering, control engineering, electronic engineering, systems design engineering, and computer engineering to create useful products.* Simply, mechatronics means using the latest technology in a very simple format to deliver exceptional results. This requires press manufacturers to have years of motion control experience and an experienced multi-disciplined in-house engineering staff that understands converters’ requirements. Today’s engineering experts are developing presses combining mechatronics engineering with the needs of the converter (both owner and operator). FTA awarded its 2008 Technical Innovation Award to OMET’s X-Flex press for exactly that reason (see FLEXO May 2008, page 32). Many label converters that have run tests on this press call the technology the answer they have been waiting for. Manufacturers are using advanced technology to deliver a solution for today’s competitive short-run market that demands better quality and repeatability. As converters consider new technology, it is important to understand the different designs available and the benefi ts that they deliver. A good analogy is that geared fl exo presses are like the old typewriter—they do the job, yet are labor intensive. The early PCs (286K) offered many features that were an improvement over typewriters, similar to simple servo presses or hybrid systems. But today’s computers—PCs, with core duo processors—offer far better performance, ease of use and a better process at a competitive price; similar to intelligent motion control systems on presses. So, if you were to purchase a new computer (or fl exo press), which technology would you buy? ■ REFERENCES *= Wikipedia ABOUT THE AUTHOR: Steven Leibin is the North American sales manager for OMET products for Matik Inc. Leibin grew up in a family business and has a hands-on mechanical background. After graduating from Northeastern University with a degree in Business Management and a minor in Computer Science, he became the general manager and sales manager at two different small companies. Leibin joined the converting industry in 2001 and quickly understood the growing need for new effi ciencies in the printing and converting arena. He lives in Connecticut with his wife and three children that keep him ever young and working. www.flexography.org AUGUST 2009 FLEXO 57