Reference Book
Each printing unit has an upper and lower inking and dampening unit. Ink
from these fountains are adjustable through a series of fountain keys. This
design is commonly used in newpaper and publishing industry.
2.Inline presses :- Each printing unit of an inline web-offset press have its
own plate, blanket, and impression cylinder and
each unit prints one colour on one side of the
web. To print on the reverse side the web of
paper must be turned to 180 degrees between
printing units by means of turner bars that expose
the unprinted side of the web to the remaining
units. Turner bars are also referred to as angle
bars. They are metal bars placed horizontal at a 45 degree angle to the feed
direcion of a printing press used to turn the moving web to flip over allowing
it to be printed on the reverse side. This press design is commonly used for
printing business forms.- Stack / Tower Presses :- They are also called vertical
blanket to blanket press. In this type of web-offset all
the units are designed in such a way that two blanket
cylinders are arranged on top of one another with the
web guided between them in a horizontal direction. The
plate cylinders, the inking units and the dampening units
belonging to each printing units are arranged at the top
and bottom respectively. Four colour printing on both
sides is produced by arranging four such blanket to
blanket units in a sequence. - Common Impression Cylinder (CIC) presses
(Satellite units):- This type of offset has
several plate cylinders positioned arround a
single large-diameter common impression
cylinder. This large cylinder supports the
substrate as it contacts a series of adjacent
plate cylinders, which lay down successive
colors. Central impression presses can have
anywhere from two to eight printing units,
with four being the most common. The major
advantage of this press is the ability to hold
excellent register.
Web operations
Paper is fed into the press from large rolls on a roll stand, replacing the pile
feeder on a sheet fed. Roll stand is a stand used with web presses to hold one