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FLEXO Magazine : August 2014
printing station is very similar to a conventional flexographic two rollers and doctor blade configuration, with the chilled drum acting as a conventional backup roller. As shown in the sketch on the left of Figure 2, the metal free area is achieved by a “vapor shielding” effect, as generated by masking fluid evaporation contrasting aluminum deposition on the selected areas. Figure 3 shows the actual printing unit installed on a metallizer. Due to the environment within the vacuum chamber and the physical properties of the printed fluid, the unit requires very specific engi- neering solutions, different than that of the average flexo station. In particular, the classical mechanism of ink collection from a tray or a DB is replaced by evaporation—basically a heated chamber will generate oil vapors at moderate temperature, due to the low pressure inside the chamber, and oil vapors will continuously condensate on the anilox roller, which will then transfer the fluid to the plate cylin- der. The design also accounts for a specially engineered DB with the function to remove excess oil from the anilox and to seal and contain the oil, preventing excess evaporation and splashing. PRODUCT QUALITY & PERFORMANCE In the past few years, quality and performances of the process have greatly improved. Now, the system will allow for a print definition within the normal limits of a conventional flexo station, but at the very high speed of a metallization process. The chart in Figure 4 sum- marizes the state of the art pattern metallization processes. The ultimate development for this technology is in register pattern metallization to a pre printed web. This development was made possible by the merging of the expertise of Galileo Vacuum (now Nordmeccanica Vacuum) and the more than 25 years of experience of the parent company Nordmeccanica, which in 1988 developed a first for the industry of coating by applying cold seal in register and out of line on a pre printed web. The new system features the same register accuracy and smaller scrap rate, while registering as allowed by the new proprietary and integrat- ed Nordmeccanica in-register technology. E xtending the application field of this process will be instrumental, primarily to the flexible packaging market, but also to diversified fields, such as the growing flexible electronic field (pattern metallized antennas for RFID tags). In this latter case, the registration control will allow the run of repeated metallic deposition steps to control the aluminum thickness, accord- ing to the electrical properties required by the specific product. All of the techniques mentioned in this article will allow for countless innovations in flexible packaging, namely in labels, pharmaceuticals, the military and a number of other applications, as made evident by the current number of projects we have witnessed in the past few years. ■ About the Authors: Giancarlo Caimmi is commercial director for Nordmeccanica Group. He holds a Ph.D. in mechanical engineering from the University “Federico Secondo” in Naples, Italy and has roughly 30 years of experience in the converting machinery manufacturing industry. He has worked in machine design, as well as in research and development departments for machin- ery manufacturers, devising new technologies in printing machinery and in coating laminating equipment. He holds international patents for both invention and innovation. Giancarlo is actively involved in industry associations, such as FTA, AIMCAL and FPA. He has been the author of articles for technical magazines and lectured worldwide in conferences on packaging, flexible packaging and converting equipment. With a university degree in chemical engineering, Fabiano Rimediotti has spent most of his profes- sional activity in the field of vacuum technology, in particular vacuum metallization. He worked for more than 25 years with Galileo Company in Italy, specializing in the design and construction of vacuum metallizers for flexible packaging and multiple applications. At Galileo, Fabiano was as- signed various roles, but his main specialization has always been process and technology for vacuum coating of plastic film and paper. He recently joined Nordmeccanica Group as process specialist, when it started, with Nordmeccanica Vacuum, the metallizing business, acquiring the exclu- sive license of Galileo’s roll to roll vacuum coaters technology and design. 44 FLEXO | AUGUST 2014 Figure 4 “A decidedly less conventional metallizing printing combination is ‘pattern metallization,’ consisting of a very peculiar ‘vacuum’ printing process, performed by a printing unit positioned inside a vacuum metallization chamber. ”