Flexography

Adapted from Wikipedia: http://en.wikipedia.org/wiki/Flexography

Flexography (also called surface printing), often abbreviated to flexo, is a method of printing most commonly used for packaging (labels, tape, bags, boxes, banners, etc.).

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.

Originally flexo printing was basic in quality. Labels requiring high quality have generally been printed Offset until recently. In the last few years great advances have been made to the quality of flexo printing presses.

The greatest advances in flexo have been in the area of photopolymer printing plates, 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.

Digital direct to plate systems have dominated the industry recently with their incredible quality and ability to print four color process as well as Offset. Companies like DuPont in Delaware and PlateCrafters in Colmar, PA have pioneered the latest technologies with advances in FAST washout and the latest screening technology. Even companies who make plates in house are going to trade shops to get these high quality plates.

Laser-etched anilox rolls also play a part in the improvement of print quality. Full color 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. One ongoing improvement has been the increasing ability to reproduce highlight tonal values, thereby providing a workaround for the very high dot gain associated with flexo print.

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 a low viscosity. This enables faster drying and, as a result, faster production, which results in lower costs. 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 very large runs of flexible packaging is rotogravure, and flexo is used for mostly large and medium runs.

Products Using Flexo

Typical products printed using flexography include brown corrugated 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.