Gravure Printing

Applications

Typical rotogravure printed products include:

• Food packaging
• Wall paper
• Wrapping paper
• Furniture laminates
• Panelling
• Greeting cards
• Magazines

Process Overview

Rotogravure printing is an example of intaglio printing. It uses a depressed or sunken surface for the image. The image areas consist of honey comb shaped cells that are etched or engraved into a copper cylinder. The unetched areas of the cylinder represent the non-image or unprinted areas. The cylinder rotates in a bath of ink call the ink pan. As the cylinder turns, the excess ink is wiped off by a flexible steel doctor blade. The ink remaining in the recessed cells forms the image by direct transfer to the substrate (paper or other material) as it passes between the plate cylinder and the impression cylinder.

The major unit operations in a rotogravure printing operation are:

• Image preparation
• Cylinder preparation
• Printing 
• Finishing

Rotogravure Inks - Solvent Based, Water Based

Rotogravure inks are fluid inks with a very low thickness that allows them to be drawn into the engraved cells in the cylinder then transferred onto the substrate. In order to dry the ink and drive off the solvents or water, which essentially replaces most of the solvent, the paper is run through Gas fired or electric fired driers. The ink will dry before the paper reaches the next printing station on the press. This is necessary because wet inks cannot be overprinted without smearing and smudging. Therefore, high volume air dryers are placed after each printing station. 

The solvent-laden air from the dryers is passed through either a solvent recovery system or solvent vapor incinerator. A typical recovery system uses beds of activated carbon to absorb the solvent. Saturated beds are regenerated by steam. The solvent laden steam is then condensed and the water and solvent separate by gravity. Greater than 95% of the ink solvents can be recovered using this process. The solvents can either be reused or destroyed by incineration.

Water based inks, used for packaging and product rotogravure, require higher temperature and long drier exposure time in order to drive off the water and lower vapor pressure constituents. As mentioned subsequent sections, Flexo and Rotogravure inks are similar and constituents are the same. 

Rotogravure Press Design and Equipment

Web-fed rotogravure presses account for almost all publication, packaging and product gravure printing. These presses are generally custom manufactured machines designed for a specific range of products. The typical press is highly automated and consists of multiple print units. The printing mechanism in a rotogravure press consists of a rotogravure cylinder and a smaller, rubber clad impression cylinder. Other types of gravure presses in commercial use today are sheet-fed, intaglio plate and offset gravure. These types of presses are used primarily for special printing applications.

process of gravure printing

Pneac.org. (2016). Printing Process Descriptions: Environment and Printing: The Printers' National Environmental Assistance Center: PNEAC: The Environmental InformationWebsite for the Printing Industry. [online] Available at: http://www.pneac.org/printprocesses/gravure/ [Accessed 17 Oct. 2016].