Flexographic Printing

Applications

This type of printing is the major process used to print packaging materials. Flexography is used to print smooth containers, folding cartons, multi wall sacks, paper sacks, plastic bags, milk and beverage cartons, disposable cups and containers, labels, loose tapes, envelopes, newspapers and wrappers for candy and food.

Process Overview

The substrate is fed into the press from a roll. The image is printed as substrate is pulled through a series of stations or print units. Each print unit is printing a single colour. As with Rotogravure and Lithographic printing, the various tones and shading are achieved by overlaying the 4 basic shades of ink (CMYK).

The major unit operations in a flexographic printing operation are:

• Image preparation
• Plate making
• Printing
• Finishing

Image Preparation

This process begins with camera-ready art/copy or electronically produced art supplied by the customer. Images are captured for printing by camera, scanner or computer. Components of the images are manually assembled and positioned in a printing flat when a camera is used (stripping process). When the art/copy is scanned, the image is assembled by the computer with special software. A simple proof is prepared to check for position and accuracy. The colour involved is colour proof submitted to the customer for approval.

Plate Making

Flexographic and letterpress plates are made using the same basic technologies utilising a relief type plate. Both technologies employ plates with raised images and only the raised images come in contact with the substrate during printing. They are made of a flexible material, such as plastic, rubber or UV sensitive polymer so that it can be attached to a roller or cylinder for ink application. 

Flexographic Printing Press

Five types of printing presses used for flexographic printing are the stack type, central impression cylinder, in-line, newspaper unit, and dedicated 4-, 5- or 6- colour unit commercial publication flexographic presses. All these types employ a plate cylinder, a metering cylinder known as the anilox roll that applies ink to the plate and an ink pan. Some presses use a third roller as a fountain roller and, in some cases, a doctor blade for improved ink distribution.

Process of Flexo 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/flexography/ [Accessed 17 Oct. 2016].