Flexography
FlexographyBy: Kathleen Cinq-Mars and Jared Andolesk

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Definition - Flexography is a form of printing that uses a flexible relief plate that can print on plastic metallic films, cellophane, and paper. It is done using a rotary printing method that means that with every turn of the printing plate a single image is made. This type of printing is used in the food packaging industries.



History of Flexography

1890 - Bibby, Baron and Sons patented the first press in Liverpool, England. It had a water based in that easily smeared causing people to refer to the device as "Bibby's Folly".

1900's - The press was developed further by many. It now had rubber printing plates and aniline oil based inks were developed.
1920's - Most presses were now made and used in Germany. They called the process "gummidruck" and it is still called that today.
1940's - By now this printing technique was used mainly for food packaging in the US and was called Aniline Printing. Food and Drug Administration classified the dyes used as unsuitable for food packaging. Because of this printing sales diminished. Companies tried to rename the printing process to make people believe it was safe but this did not work.
1949 - The Food and Drug Administration approved the printing process because they were now using newer and safer inks. However, sales continued to decline and food manufactures still did not trust the ink. Packaging representatives decided that they needed to rename it completely to show it was safe to use.
1951 - The president of Mosstype Corporation, Franklin Moss, held a contest in his journal The Mosstyper come up with new names for the printing process. After reading and considering over 200 different names they settled on three possible names: "Permatone Process", "Rotopake Process", and "Flexographic Process". Another poll was sent out and the readers of the journal chose "Flexographic Process".


Process of Flexography

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In the simplest form of flexographic printing there are 4 main parts to the machine:
  1. The Fountain Roll
  2. The Ink Metering (Anilox) Roll
  3. The Plate Cylinder
  4. The Impression Cylinder

In order to get the ink from the ink pan onto the substrate it must go through a number of simple steps. First, the Fountain Roll spins in the ink, piking up a rather heavy flow if ink from the fountain. It then transfers the ink to the Anilox Roller. The Anilox Roller has engraved cells on it that carry a certain amount of ink that can not be seen by the naked eye. You must use a microscope in order to see it. Then comes time for The Plate Cylinder, it is the part of the machine that has the printing plate, this is a soft flexible rubber. Tape is used to attach the plate to the Plate Cylinder. The next step is the Impression Cylinder. This applies pressure to the Plate Cylinder and then the image is transferred to the preferred substrate.


Types of Inks

When it comes to Flexographic printing there are only five types of inks that can be used. They are:
  1. Solvent based inks
  2. Water based inks (Most popular in printing)
  3. Electron Beam Curing inks
  4. Ultraviolet Curing inks
  5. Two part chemically curing inks


Substrates

A substrate is the material that can be printed on in the flexographic process. Almost anything can be printed on. It ranges from the tinniest wrapping on a toothpick to the plastic that covers a new mattress.
  • Paper and Paperboard - paperback books, envelops, paper cups, milk cartons.
  • Corrugated Board
  • Polyethylene
  • Polyester Film
  • Polypropylene
  • Cellophane
  • Latex Saturated Papers


Where do we see examples of Flexography?

We see examples Flexography all the time all day every day. Go look in your kitchen cupboards and refrigerator right now and you will see examples of Flexographic printing everywhere. It is the chip bags, milk bags, granola bars wrappers, cereal boxes, and every single label on all of your bottles and containers. It is on the plastic bag you buy your bread in, the plastic that keeps your cheese fresh. It is literally everywhere! Not only are food packages examples, but cleaning products, balloons, and cardboard boxes are as well. The list goes on an on.

i-flexo.jpg Technology_Flexography_Product.jpg coke_holiday.jpg flex_photo_1.jpg
Flexo2.jpg Flexography2.jpgGet-Well-Soon-Mylar-Balloons-Bouque.jpg




What are the advantages of Flexography printing?

Flexography has an advantage over lithography in that it can use a wider range of inks, water based rather than oil based inks, and is good at printing on a variety of different materials like plastic, foil, acetate film, brown paper, and other materials used in packaging. Typical products printed using flexography include brown corrugated boxes, flexible packaging including retail and shopping bags, food and hygiene bags and sacks, milk and beverage cartons, flexible plastics, self adhesive labels, disposable cups and containers, envelopes and wallpaper.

A number of newspapers now eschew the more common offset lithography process in favour of flexo. Flexographic 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 up to 600 meters per minute (2000 feet per minute) are achieveable now with modern technology high-end printers.

Flexography is the fastest growing conventional printing process, especially in packaging such corrugated containers and flexible films. It has also made significant advances in publication printing, particularly newspapers. Since the standards in flexographic printing quality has improved so much, it is now used extensively for process colour printing, as well as spot colour on a wide variety of substrates.

Advantages of flexography:
  • Prints on wide variety of absorbent and nonabsorbent substrates.
  • Prints using resilient rubber or photopolymer image carrier,so that millions of impressions can be made.
  • can print more than 10 colors if multiple print station are used.
  • It uses fast drying inks which might be solvent based, water based or UV curable.
  • Cost effective


Read more: http://wiki.answers.com/Q/What_are_the_advantages_and_disadvantages_of_flexography_printing#ixzz1d2hQyGnW


Disadvantages of flexography:
  • Poor shadows, the impressions per plate are more limited than offset.
  • Each press is not the same. Work done on the prepress has to be fingerprinted for the individual press.
  • Problem with bleeding
  • Haloing ( aline that surrounds a printed image.) Some of the halo causes are cupped edges of a plate, out of round plate cylinder, and excess squeezing of the substrate and plates.
  • Overall, flexographic printing quality lacks fine color detail and vibrance that is seen mostly in the final products.



What makes Flexography printing relevant today?

Printing has become a part of everyday life for a vast majority of the world. Flexography is the world's fastest growing print technology. We come in contact with items printed with flexo on a daily basis. Flexo is used to print newspapers, comics, envelopes, packages such as software, cereal boxes, shampoo bottles, labels, soda bottle wrap and cartons, frozen food bags, bread bags, and milk cartons, just to name a few. Take away any one of these and think how it would affect the social systems.


Who and how is Flexography used?

The use of flexographic printing presses is on the rise. There are two primary reasons for this:
  1. It is a relatively simple operation
  2. It is easily adapted to the use of water-based inks.

The widespread use of water-based inks in flexographic printing means a large reduction in VOC emission compared to the heatset web or gravure printing processes.

Publication flexography is used mainly in the production of newspaper, comics, directories, newspaper inserts, and catalogs. Packaging flexography is used for the production of folding cartons, labels, and packaging materials. Large quantities of inks are used during normal runs on flexographic presses; however, some printers are able to recycle a majority of their spent inks and wash waters. Major chemicals used in flexography include platemaking solution, water and solvent based inks, and blanket/roller cleaning solvents.
  1. ^ http://en.wikipedia.org/wiki/Flexography
    http://www.wmich.edu/pci/flexo/
    http://www.daclabels.com/What_is_Flexography_/what_is_flexography_.htm
    http://www.flexoexchange.com/gorilla/flexo-student-perspective.html
    http://www.castleink.com/_a-flex.html