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Sheet-fed Gravure
Applications:
Sheet-fed gravure is used when very high quality impressions are
required. Uses include the production of pictorial impressions for art
books and posters and short runs of high quality packaging material such
as cosmetics cartons. Sheet-fed gravure presses are also used for overall
coating of products printed by sheet-fed offset to provide high brilliancy
to the printed sheet and for the application of metallic inks that cannot
be applied by the offset method. Additionally, sheet-fed gravure presses
are used to produce proof copies prior to large rotogravure runs (GAA
1991). More information...
Process Overview
The sheet-fed gravure press differs from the web-fed press primarily in
that paper is delivered to the press as pre-cut sheets instead of a
continuous web. The printing mechanism in a typical sheet-fed gravure
press consists of a gravure cylinder and an impression cylinder of the
same size. The plate itself is a flexible metal sheet wrapped around a
carrier cylinder equipped with a gripper to hold the plate in place during
printing.
The offset gravure press is a standard gravure unit to which a
rubber-covered transfer roller has been added. The image to be printed is
transferred from the gravure printing cylinder to the roller. The transfer
roller then prints the image on the substrate. More Information...
The transfer of the image from the cylinder to the roller is similar to
the transfer method used in offset lithography. Offset gravure presses are
used to print substrates with irregular surfaces such as wood veneer or
decorated metal (GAA 1991).
In some printing processes, both sides of the web can be printed
simultaneously. However, in gravure, printing of one side of the web must
be completed before the other side can be printed. In practice, the web is
printed on one side, rewound, flipped over, then printed on the other
side. Some rotogravure presses are designed with a turning station that
rotates the web 180 degrees. The web is then run through a parallel paper
path with different cylinders that prints the opposite side of the paper.
These presses are called double-ended presses. |