Cylinder Arrangements
Although the three-cylinder arrangement is the most common for sheetfed presses a number of other cylinder arrangements may also be encountered. Following is a brief overview of six possible cylinder arrangements (Figure 3-2):
. Two-cylinder. A special design that combines the impression cylinder and plate cylinder into one large cylinder. The other cylinder is a standard blanket cylinder.
. Three-cylinder. The most common cylinder arrangement that contains a plate cylinder, a blanket cylinder, and an impression cylinder.
. Four-cylinder. This design is basically a three-cylinder arrangement with the addition of a delivery cylinder.
. Perfector (blanket-to-blanket). A flexible design that enables the sheet to be printed in two colors on one side or one on both sides of the sheet during one pass through the press.
. Two-color common-impression cylinder. A special press dedign that provides for two plate cylinders with complete inking and dampening systems and two blanket cylinders. A common-impression cylinder accommodates both blanket cylinders.
. Two-color common-blanket cylinder. This design entails two plate cylinders with complete inking and dampening systems and one blanket and impression cylinder. Both ink colors from the two plates are transferred to the one blanket.
Exceptions exist to this nearly right-angle (L-shaped) arrangement of cylinders. With one type of metal decorating press, the cylinders are stacked directly above each other so that the rigid metal sheets can pass through the printing nip (the line of contact between the blanket and impression cylinders) without being bent around the impression cylinder. Another exception is a press that a single, oversized cylinder that is used a both the plate and impression cylinder. Yet another is a press that has a single oversized cylinder functioning as the impression cylinder for two printing units.
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