Flexography

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Flexo redirects here. For the Futurama character, see List of recurring robot characters from Futurama.

Flexography (also called surface printing), often abbreviated to flexo, is a method of printing most commonly used for packaging.

A flexo print is achieved by creating a mirrored master of the required image as a 3D relief in a rubber or polymer material. A measured amount of ink is deposited upon the surface of the printing plate (or printing cylinder) using an anilox roll. The print surface then rotates, contacting the print material which transfers the ink.

Flexo is so named because it was originally used as a method of printing onto corrugated cardboard which has a very uneven surface. It is required that the printing plate surface maintain contact with the cardboard, which it does by being flexible. Also unprinted high points on the cardboard must not get printed by ink remnants not on the plate surface, which is achieved by ensuring a sufficient depth for the non-print areas of the plate.

Originally flexo printing was very low quality. In the last 3 decades great advances have been made, including improvements to the plate material and the method of plate creation—usually photographic exposure followed by chemical etch, though also by direct laser engraving. Laser-etched anilox rolls also play a part in the improvement of print quality. Full colour picture printing now occurs, and some of the finer presses available today in combination with a skilled operator allow quality that rivals the lithographic process.

Flexo has an advantage over lithography in that it can use a wider range of inks and is good at printing on a variety of different materials. Flexo inks, like those used in gravure and unlike those used in lithography generally have low viscosity. This enables faster drying and as a result, faster production, that means low cost. Printing press speeds of 450 meters per minute are regular with modern technology high end printers, like Windmoeller und Hollscher or Schiavi type. The main printing process worldwide for flexible packaging are rotogravure, for very large runs, and flexo for large and medium runs.

Typical products printed using flexography include brown cardboard boxes, flexible packaging including retail and shopping bags, food and hygiene bags and sacks, flexible plastics, self adhesive labels, and wallpaper. A number of newspapers now eschew the more common offset lithography process in favour of flexo.