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Flexographic Printing Process
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There are three basic types of flexographic printing presses: stack (decks stacked one over the other), C.I. (decks around a single counter-impression cylinder) and in-line (separate color stations). The choice depends on printing applications, however, since they hold excellent register CI presses are prevalent among converters printing extensible films.
A modern flexo printing system consists of a closed chamber doctor blade, the ink metering roller or anilox roller, the plate cylinder and the impression cylinder.
The ink is pumped into the chamber. Two blades make up this system: one is the reverse angle blade that shears the ink from the surface of the anilox roller and the other is a trailing blade. The anilox roller is covered with tiny engraved cells and supplies a fine film of ink to the printing plate mounted on the next roll in sequence, the plate cylinder. The ink is then carried by the raised portion of the plate and transferred onto the substrate. The impression cylinder supports the substrate when it contracts the printing plate.
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Between each print deck there is an interstation dryer that removes enough volatiles from the ink so that the next print deck may apply another colour without altering the previous one. After the last print deck there is a much longer dryer that completes the heat setting of all the inks applied.
After the substrate has been printed, it is taped to a shaft and wound back into the original roll form.
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