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FLEXO Magazine : July 2007
w w w . f l e x o g r a p h y . o r g J U LY 2 0 0 7 F L E X O 3 7 bEginnEr flexographer shipped in wooden crates that are referred to as bulk packs. It’s best to keep the material in the original packaging until it’s ready to be used. It’s also a good idea to store the plate material about waist high, so that the platemaker can access the material easily and does not have to stretch or bend over too far to reach it. To start a job, always have a plan. Make sure the platemaker knows where the material is and make sure there is enough time to complete the job at hand. It is important to check all of the equipment planned for use to ensure that it is in working order and that it is not being used by someone else, with the idea being to handle the material as little as possible. When removing a sheet of ma- terial from its original packaging, always pick it up from the closest edge using two hands with the tips of the fingers, touching as little of the plate as possible. Spread hands from left to right so that they are about one-third the way in from each end of the plate. Then, slightly lift the plate and begin sliding the plate. As the end of the plate starts to get closer to the edge, start lifting without bending and remove the plate from the box allowing the end of the plate to point to the floor. At this point, the removable protective coversheet should be facing the operator. It’s critical that the plate not be dropped or bent to the point that it kinks the polyester backing. If this happens, the plate can be dam- aged and become unusable. Once the plate is in hand, grip it firmly with the finger tips, and carry the plate as close to the body as possible without touching it, and just far enough away so as not to bump it while walking. If a mobile loading table is available, lay the plate on the table and move it to the next step in the process. Many flexo platemakers are now taking advantage of digital plates because of the benefits they can provide such as sharper dots, the elimination of film, no need to expose plates under vac- uum, etc. Along with these benefits comes the potential downside of damaging the mask. Digital plates have a carbon mask that is ablated away using a computer to plate (CTP) image devices. When handling a digital plate the platemaker must be very care- ful not to scratch the mask as it can render the plate unusable. The next step in the process should be to move the plate to a cutting table to be cut down to size if required. Once the plate has been cut to the appropriate size it’s then ready to be exposed. Exposure units come in many dif- ferent styles and formats. Most units have either a top set or both a top and bottom set of ultraviolet (UV) lamps. If using a unit that has just the top UV lamps, lie the plate face down with the coversheet in place and back-expose the plate first. Once the plate has been back- exposed, it can then be carefully turned over to be face exposed or moved to CTP imager, if working with a digital plate. An exposure unit with top and bottom UV lamps eliminates the step of turning the plate over. After the digital plate has been ab- lated, apply the same technique that was used to remove the plate from its original packaging to remove it from the CTP imager, making sure to not touch any of the imaged area and as little of the plate as possible. The plate can then be carefully moved to the exposure unit to complete the exposure process. Once the plate has been exposed, carefully roll the plate with the image to the inside, making sure not to kink the polyester backing. Now move the plate to the appropriate processor (depending upon whether the plate material is analog, digital or thermal) to remove any uncured polymer. Once a thermal plate has been processed, care- fully remove the plate by touching as little of the plate as possible and place in light finisher. The analog and digital plates that have been processed in solvent will need to be placed in the dryer and dried 1.5 to 2.0 hours before being placed in a light finisher. Finished plates should be stored somewhere flat and out of direct light and in an area not ex- ceeding temperatures above 100 degrees F (38 C). When plates are left on cylinders or stored on a curved position this increases the surface ten- Even with all of these advances, there is still a certain amount of manual plate handling the operator must perform in order to complete the plate making process. Damaging the mask can render the
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