All web-fed gravure presses start from an unwinder, which serves the purpose of unwinding a roll of substrate, deeping, keeping adequate tension on the web.
The printing unit, figure 4-1, the heart of the gravure press, consists of the following components, regardless of the application:
. The image carrier, a cylinder engraved with the image to be printed or transfered.
. An ink fountain, a large ink well positioned beneath the cylinder, extending the width of the press unit.
. A doctor blade assembly containing a blade which wipes excess ink from the nonimage areas of the image carrier.
. An impression roller, a rubber-covered metal cylinder which holds the substrate against the engraved image carrier to obtain proper ink transfer.
. A dryer, consisting of a controlled source of heated air, regulated to provide optimum drying of inks or coatings and remove ink carrier vapors.
The limited number of major press components and their physical simplicity makes gravure easy to automate, simple to operate, and readily adaptable for additional in-line converting operations.
Modern gravure presses are equipped with many levels of automation -- including programmable control of all press sequences -- and digital drives.
. Fault detection, including on-line video monitoring.
. Preset of job variables.
. Production statistics.
. Ink consumption data analysis.
. Paper consumption data analysis.
. Waste analysis.
In many recently delivered presses, the conventional press main consoles are replaced by computerized controls where video displays permit control of the press by means of touch screens or keyboard.