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FLEXO Magazine : July 2007
hot technologies 2 6 F L E X o J U LY 2 0 0 7 w w w . f l e x o g r a p h y . o r g Bigger the Better Due to the absence of any transmission mechanism, the linear motor fits well to any size machine, but in reality the wider the press is, the larger the benefit to the linear motor. When the press is wider, it requires more force to move the cylinders and more force to keep them in position. This means bigger size motors, balls, and screws, and other components which can create space problems. If the press is equipped with linear motors the increase in size in the print station is very little, and the larger room re- quested normally for the bigger size machines is negligible compared to the standard size. So far, linear drives have been used to move the cylinders front and back. The next generation ma- chine, available in the market at the beginning of 2008, will be equipped with linear motors for the side reg- istration control. The linear motor must not be confused with the mo- tor that drives the printing cylinder in its rotation; this means the linear motor has nothing has to do with the print longitudinal register, which is still controlled by rotary servos, such as the torque motors. the Best impression The higher position precision granted by linear motors makes it easier to cope with the substrate thickness. The linear motor can really “kiss” the substrate in the area of tenths of a micron, which cannot be achieved by few, if any, other flexo presses in the world. Linear motors in fact do not have any minimum step, while the step motor and the ball screws require a step approach to the final position. In reality, the limit of the linear motor is represented by the resolution of the encoder. If there was available in the market an encoder capable of a resolution equal to 0.0001 microns, that would also be the minimum movement of the cylinder. In other words, there is no limit for the resolution and precision of a linear motor, which gives the best proof of its capability with the very, very thin materials, where the error percentage in the positioning could be very high, for conventional motor machines. In exactly the same way, the linear motors are more “gentle” against the anilox rollers, since they can approach them more precisely, without unnecessary pressure. The linear motor will open new horizons to flexo printing. We can position the mandrels so precisely against one another and against the substrate, so that, declaring that our target is the elimination of the dot gain is not a dream. This is be- ing worked on already. There are many other areas that need to increase their precision in order for this to happen, but until now there was little reason for having any higher precision in items such as stickyback, plate, sleeve, and base technology.? ABOUT THE AUTHOR: Claudio Maggio is managing director for Converting Technology Srl. He has been in the flexo industry for 28 years. He worked for Carraro before co-founding Uteco S.p.A. in 1985. For more information about Converting Technology or linear motors, contact Gary Anderson at email@example.com. The linear motor can really “kiss” the substrate in the area
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