Editing Flexography (section)

==Operation==

===Operational overview===
[[File:Flexographic printing diagram.svg|thumb|right|600px|Diagram of a typical flexographic printing apparatus, illustrating the general operating principle.]]
'''1. Fountain roller'''<br />
The fountain roller transfers ink located in an ink pan to a second roller, an anilox roller.
In modern flexographic printing, the anilox roll is referred to as a type of meter or metering roller.

'''2. Anilox roller'''<br />
The anilox roll is a unique characteristic of flexography. The anilox roller transfers a uniform thickness of ink to a flexible printing plate. The anilox roll has finely engraved cells with a particular ink capacity, viewable with a microscope. These rollers are responsible for transferring inks to the flexible printing plates mounted on the plate cylinders.

'''3. Doctor blade (optional)'''<br /> An optional doctor blade scrapes the anilox roll to ensure that the ink to be delivered to the flexible printing plate is only what is contained within the engraved cells. Doctor blades had predominantly been made of steel, but advanced doctor blades are now made of polymer materials with several different types of beveled edges.

'''4. Plate cylinder'''<br />
The plate cylinder holds the printing plate, which is made from a soft flexible rubber-like material. Tape, magnets, tension straps and/or ratchets hold the printing plate against the plate cylinder.

'''5. Impression cylinder '''<br />
The impression cylinder applies pressure to the plate cylinder where the image is transferred to the image-receiving substrate. 
This impression cylinder or "print anvil" is required to apply pressure to the plate cylinder.

===Flexographic printing inks===
{{main|Flexographic ink}}
The nature and demands of the printing process and the application of the printed product determine the fundamental properties required of [[flexographic ink]]s. Measuring the physical properties of inks and understanding how these are affected by the choice of ingredients is a large part of ink technology. Formulation of inks requires a detailed knowledge of the physical and chemical properties of the raw materials composing the inks, and how these ingredients affect or react with each other as well as with the environment. Flexographic printing inks are primarily formulated to remain compatible with the wide variety of substrates used in the process. Each formulation component individually fulfills a special function and the proportion and composition will vary according to the substrate.

There are five types of inks that can be used in flexography:<ref>[http://www.encyclopedia.com/doc/1G1-57294024.html]{{dead link|date=June 2014}}</ref>
*solvent-based inks
*water-based inks
*electron beam (EB) curing inks
*ultraviolet (UV) curing inks
*two-part chemically-curing inks (usually based on [[polyurethane]] [[isocyanate]] reactions) - although these are uncommon at the moment

Water based flexo inks with [[particle size]]s below 5&nbsp;μm may cause problems when [[deinking]] recycled paper.

===Ink controls===
The ink is controlled in the flexographic printing process by the ink system. The ink system contains an ink pump, anilox roll and either a [[fountain roll]] system or [[doctor blade]] system. The fountain roll or two-roll system has one roll spinning in an ink pan pressed against the anilox roll to transfer a layer of ink to then be applied to the printing plate. This system is best used for low quality print such as flood coats and block lettering due to its inability to produce a clean wipe of the anilox roll. The doctor blade system can either be an open single blade system or an enclosed dual blade system. The single blade system uses an open ink pan with a roller that is then sheared with one doctor blade to create a uniform layer of ink to be distributed. The remaining ink sheared from the anilox roll will collect in the ink pan to then be pumped back into the system. The cylinder plate, anilox, and doctor blade are independently controlled by hydraulic, pressure and/or pneumatic systems. This system is best used for low to mid quality print work - usually found in corrugated box printing. The dual blade system is an enclosed system that has one doctor blade for doctoring the ink and one containment blade that contains the ink in the chamber and allows ink from the anilox roll back in. Dual blade systems require 2 end seals and adequate chamber pressure in order to maintain the tight seal between the ink chamber and the anilox roll. This system is best used for high quality, intricate print designs, like those found in the label industry.