Intro To Flexographic Printing

History

Flexographic printing has gained steadily in popularity over the past half-century due to its wide range of applications and flexibility with many different substrates. With the capability to print upwards of seven passes in a single process, flexography offers more process colors than conventional offset printing as well more options when it comes to spot colors and effects. Despite the correlation, flexibility is not what gave flexography its name.

Flexography or “Flexo” was first patented by Bibby, Baron and Sons in Liverpool, England in 1890. It was the first known printing method to utilize a flexible printing plate, rather than the standard rigid metal plates used in offset presses. However, the water-based ink used in the first trials smeared terribly, and the patented device became known as “Bibby’s Folly.”

In the early 1900s, the process evolved into “Analine Printing,” which utilized rubber printing plates and analine oil-based ink. The presses were primarily made in Germany where the process was referred to as “Gummidruck.” Modern flexographic printing is still often referred by its predecessor's name in Germany.

The modern version of flexography utilizes flexible photopolymer printing plates that are laser etched with the image or relief to be printed. This laser etching process is referred to as digital platemaking.

How Flexography Works And How It Differs From Other Printing Methods

Flexo printing differs from other standard forms of printing in the way its plates are constructed and utilized, the properties of the inks used, and the relative speed at which production can be accomplished.

Flexo differs from offset printing in that no intermediary transfer step is required. In the case of offset the ink is transferred to a printing plate, then “offset” to a series of rollers before being transferred to the final substrate - whereas in Flexo printing the ink is transferred directly from plate to substrate.

As the plates used in flexographic printing are made of flexible photopolymer, they can be easily wrapped around a cylinder. The cylinder then rolls over the substrate, transferring the ink directly from the printing plate to the surface being printed.

As in offset printing, an individual plate and roller are required for each color printed. In offset, the artwork is limited to what can be produced by CMYK process print and the possible addition of spot colors. Flexo printing machines can have 7-9 stations, allowing for a mixture of process printing and additional roller stations reserved for spot colors and effects.

Flexographic printing can be utilized on a broader range of non-porous substrates compared to offset; such as foil, cellophane, plastic, and metal. Offset is limited to flat, smooth, porous surfaces.

Depending on the desired substrate, effects and production speed; water-based or UV curable ink can be utilized. UV curable ink can speed production time as it doesn’t need to be removed from the press and cleaned off the plates every day. Water-based inks tend to dry on the equipment if left there. UV inks also enable higher running speeds when the printing press is in service.

In the packaging realm, flexographic printing is an excellent option for decorating laminate tubes, labels, and secondary packaging, but is often more expensive than other print methods.

Edward

Posted by Edward
on Thu, December 6, 2018

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