Flexographic printing is a type of roll feed web printing process that is commonly used to print large volumes of packaging and labels. Flexo-presses can print on various types of films, papers, corrugated, foils, and paperboard with high speeds reaching up to 500 to 2000 feet per minute. Many types of products are printed on a flexographic printing press such as cartons, plastic bags, gift wrap, wallpaper, folding cartons, disposable cups, plates, envelopes, and more.
The History of Flexographic Printing
Flexographic printing originated with the development of synthetic and natural rubbers. The letterpress of the late 1800s was the dominant type of printing with other processes such as lithography still in formative development. It was discovered that the letterpress could be set into plaster, with an unvulcanized liquid rubber poured into a mold to make a rubber stamp. This rubber stamp concept was applied to printing plates and was used for printing on surfaces although did not yield quality results with conventional processes, particularly on corrugated products.
In the 1930s, synthetic rubbers made these rubberstamps much more reliable than natural rubber and the effective process of “aniline printing” was developed, which is what flexographic printing was known as until the late 1950s. During the 1930s and 40s, the development of etching on gravure cylinders progressed to developing ink rollers to transfer ink to substrates with a controlled process through cells that effectively metered the ink. This roller was coined the anilox roller and is still the basis of the modern flexography press today.
The term aniline printing was derived from the type of dye used in the inks, which was declared toxic by the FDA in the 1930s. By then aniline printers used different types of inks but the name was never changed. Because of the negative association with toxicity, and especially the use of printing for food packaging processes, it was determined that the name of this process had to be changed and in 1952, suggestions from industry leaders and a special committee formed by the Packaging Institute settled on the name of “flexography” or the “flexographic process”.
Various Configurations of Flexographic Presses
There are a wide variety of flexographic press configurations as in all printing processes, but the basic design of a flexographic press is comprised of the following:
Ink pan – where the Flexo ink which is typically a volatile, thin liquid ink is stored, also called the ink fountain.
Fountain roller – a roller that picks up a thick film of ink from the ink pan and transfers it to the metering roller.
Metering roller – also known in flexography as the anilox roller which is typically a ceramic covered or chrome roller with small, engraved cells or pits.
It is the pressure between the fountain roller and the anilox roller and the revolution speed of these two rollers (the fountain roller typically rotates at a slower speed than the anilox roller) which causes a wiping effect on the anilox roller allowing only the ink stored inside the cells to be transferred to the plate. The difference in the rotating speed of these two rollers also eliminates a problem called ghosting or mechanical pinholing which occurs when ink is not uniformly replenished to the surface of the anilox roller.
Various configurations are available for flexographic printing presses, such as within an enclosed system where the anilox roller sits in the ink fountain itself which eliminates the need for a fountain roller. Ink metering can be performed with a doctor blade, the angle and pressure provide uniform ink metering. An enclosed inking system can feature two doctor blades with one on the top and one on the bottom of the anilox roller, with the ink reservoir located in between them.
An experienced manufacturer of web finishing equipment like Tamarack® Products can help to configure flexographic printing with customized features to meet your specific application requirements.
Tamarack® Offers Flexo Press Printing Solutions
Tamarack® Products is a leading global manufacturer of web finishing solutions such as the P500 Inline on Flexo Press integrated labeling system.
Tamarack® Products offers Flexo press integrated product solutions for transferring tapes, laminates, creating integrated labels, cards, forms, and other products such as holograms and scratch-off materials. We offer customized solutions to meet your unique finishing specifications. Contact us to learn more about our flexible and modular Flexo press integrated product solutions.