Innovation in Flexography

To kickoff this year’s Innovation in Print Processes series, this article takes a look at some new technologies and materials that are making the flexographic (a.k.a. flexo) printing process more profitable for print companies, easier for press operators, and more attractive for brand managers. Recent studies report the global packaging market is approaching a value of $1 trillion annually – what a time to be a flexographer!

Even more digital automation

The past decade has seen many advancements in the digital automation of flexographic workflows. There have been many innovations in the area of colour calibration and automatic machine component adjustment. With integrated prepress systems, advanced visual and pressure sensors, precise servo motors, and robust digital control panels, flexo presses are able to print higher quality products, with less waste, in shorter lead-times.

Specifically, flexo presses now have better image control at varying run speeds. Operators can be confident that the quality achieved during makeready is maintained at high speeds with the automatic checking, adjusting, and controlling of impression and register on-the-fly. Some presses now even have total job recall, meaning that all settings used for a previous run can be recalled from a database and used to setup the press within minutes. This automation makes presses easier to run; it can reduce the amount of training time required on machinery and can increase throughput since processes become more efficient.

Closing the “digital loop” even further between prepress and press is a focus for automation companies right now. GUIDU, a manufacturer of printing and converting machines from Italy, has developed a workflow that 100% cross-checks the output of a printed piece with the original PDF file generated in prepress while the press is in production. Never before has the printed dot been so close to perfect in flexo!

Next generation doctor blades

For those unfamiliar with the flexo process, the doctor blade is a key component of most flexographic inking systems. It is a thin disposable blade within the inking unit that removes excess ink from the anilox roller before it’s transferred to the plate cylinder. Without a clean wipe of the anilox roller, too much ink would transfer to the printing plate, causing a host of printing problems.

Traditionally, doctor blades are made of steel or plastic. Steel, because of its thinness and stiffness, is capable of achieving a fine point of contact, enough for a clean wipe on high line screen anilox rollers. But there’s a downside – they are sharp and more dangerous for operators to handle. Traditional plastic doctor blades, on the other hand, cannot achieve the same stiffness without being thicker. As they wear, their thickness prevents them from maintaining a fine contact area with the anilox and more contact area develops, causing changes to the tonal value and dot gain. Although they are safer to handle, they cannot produce the quality cut that a steel blade can. Introducing the polymer doctor blade. Polymer doctor blades are a new alternative to steel for producing detailed graphics. They use the latest polymers and tip engineering to form a blade that cuts like steel but is safe to the touch.

Narrow web, wide colour gamut

Narrow web flexo presses are increasingly being used beyond labels for package printing because of their efficiency with shorter runs and their integration flexibility with other printing and converting processes. A recent trend, which is making narrow web even more attractive, is bringing an expanded colour gamut (EG) to the platform. Brand managers are constantly demanding more colourful and complex designs for their product packaging in order to give their products the edge.  EG can help with that.

An expanded colour gamut is typically comprised of seven base colours: CMYK + Orange, Green, and Violet or Reflex Blue. Combinations of these inks are able to reproduce 90-95% of the PMS colour palette – a huge improvement over traditional CMYK. EG can help achieve richer, more saturated colours that pop. Furthermore, they provide better colour consistency and repeatability, reduced makeready times, and the ability to print a combination of packages requiring different colours in one run. Ultimately, EG can eliminate the use of most spot colours and eliminate ink inventory by up to 90%! Until now, most EG efforts have gone into large central impression flexo presses, but service providers are beginning to add narrow web EG to their repertoire.

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