Digital platemaking systems share the field today with conventional equipment, but they are well liked and growing in popularity.
By Jack Kenny
Despite advances in technology and the increasing popularity of digital systems, flexographic printing plates are still made the old-fashioned way by many converters. This is so for many reasons: Nothing is wrong with the existing equipment, which produces perfectly usable plates; the printer isn’t sold on the digital technology; the investment in a new system is greater than the printer can afford at the moment. The conventional equipment is available today, brought right up to 21st Century standards. But the digital plate processors are winning converts at a steady pace.
Plate processing is not astrophysics, but it requires a level of skill by a trained and dedicated staff. The process requires practice and knowledge of the basic properties of photopolymer, the workings of the processing equipment, and how the finished plates perform on the press and in contact with inks. Platemaking has steadily been moving away from the “art” arena and into science, as a perusal of FIRST (Flexographic Image Reproduction Specifications & Tolerances) will immediately show.
Making a conventional flexo plate involves the output of the film containing the image to be printed, the exposure of the film to the photopolymer in a UV exposure unit containing a lamp or bank of lamps, and equipment that washes away the unexposed portions of the plate by use of solvents, or by water containing detergent. The process is followed by drying, which must be thorough before a plate can be used for printing.
Six years ago we reported the gradual acceptance in the industry of digital platemaking. In the few years since then, digital platemaking has grown exponentially, allowing for the production of plates without the use of solvents, and finished products that are consistent plate after plate.
Digital platemaking makes use of a laser inside a processor. The plate itself is covered with a mask that is ablated during the laser imaging process. After that, it is exposed to UV light, and then placed into a thermal plate processing device, which removes the unwanted material from the plate surface using a dry method, and ejects a plate that is ready for mounting.
The first of these dry plate processors was introduced by DuPont about a decade ago. The Cyrel FAST system is a staple of the flexo trade shop today, and is utilized in many converting plants along with the digital imagers.
The following is a look at the components of the platemaking processes, both conventional and digital, from a variety of suppliers.
EskoArtwork’s most recent CDI digital plate processor,
the Spark 1712, which images a smaller plate or film.
EskoArtwork’s CDI Spark 2530 is a digital plate imager that can image a plate up to 25" x 30". The 2530 has proven to be the company’s most popular imager in the narrow web industry. Last year, however, the company rolled out a smaller unit, the Spark 1712, a small footprint plate and film imager specifically for narrow web.
“Our assessment is that there is substantial interest among trade shops and flexo converters with small narrow web presses who typically process 2,000 square feet of material manually,” says Jan Buchweitz, EskoArtwork’s CDI product manager. “This is a film replacement market that fears that their film imagesetters are becoming obsolete or are facing expensive repair costs. Because CDIs are so flexible, it allows users to continue to image film, along with the opportunity advance to a digital workflow, direct to plate.
“The tremendous thing about this small imager is that most of this market runs solvent flexo plates – although dry film processing is also available. With this simple addition, no further changes are necessary for these companies to move from analog to digital and ensure their technology workflow for years to come.”
The CDI Spark 1712 can image digital flexo plates, foil-based digital letterpress plates, digital silkscreens, chemistry-free film such as PCI Laserpoint II, and chemistry-free offset plates. The company says that converters who switch from conventional to analog film with a CDI “generally report a 20percent cost reduction in their plate making.”
The 1712 can image plates and ablative film up to an A3 (16.5" x 11.8") size and 0.12" thick. At its highest image resolution of 2540 ppi, it can image a full size plate in 9 minutes 30 seconds with effective screen rulings up to 175 lpi. It is bundled with the FlexRip 1712 with EskoArtwork screens (circular, square round, elliptical), and the Grapholas front-end software package.
The DuPont Cyrel FAST thermal plate processor
The Cyrel FAST 1000TD unit allows the production of Cyrel FAST finished plates of up to 35.4" x 47.2". Removal of the unwanted plate material is accomplished by the use of a nonwoven blanket that traps the waste photopolymer, and is later recycled.
Anderson & Vreeland
Anderson & Vreeland, a major supplier of prepress equipment, provides both conventional (solvent and water-wash) and digital platemaking systems.
A FlexoLaser imager from Anderson & Vreeland
FlexoLasers are compatible with all commercial ablative masked photopolymer plate materials, whether solvent or water-wash, and there is no limitation to plate thicknesses.
ThePiccolo FlexoLaser is the model for narrow web applications.
Anderson & Vreeland also makes the AV8000, a combination exposure, washout, dryer, and detack unit that has been engineered for high quality, low volume platemaking applications up to 12" x 18". The processor includes a spiral two-brush rotary washout unit, high intensity exposure, four drawer dryer and plate finisher. Washout operations are controlled by a SmartPanel PLC processor. Features include automatic drum positioning with forward and reverse jog for easy removal of plates.
Kodak’s contribution to the platemaking field for the flexo label printer is the Flexcel NX Digital Flexographic System. Within that system is the Trendsetter NX Imager, which is available in narrow and mid-web formats. They use Kodak Squarespot Imaging Technology for process control, and can produce an image dot size as small as 10 microns.
Following exposure, the imaging layer is laminated to a Kodak Flexcel NX Digital flexographic plate. The result, says Kodak, is a digital flexo plate that eliminates highlight drop-off and provides exceptional printing results.
The hybrid option for Trendsetter NX Mid and Narrow Imagers enables the imaging of both flexo and offset plates on the same device.
MacDermid Printing Solutions
Another thermal plate processing unit is the LAVA, manufactured by Macdermid Printing Solutions. The LAVA 2530 is configured for narrow web applications and is able to generate press-ready plates in under an hour.
The Lava System utilizes a specially developed Digital MLT photopolymer plate material that can be processed in MacDermid’s thermal or conventional solvent type processing systems.
MacDermid also produces a wide range of photopolymer plates, both conventional and digital.
Several years ago, Stork Prints introduced the Direct Laser Engraver (DLE), which directly engraves images onto flexo plates using a laser. Stork DLE systems are available direct from the company or through Anderson & Vreeland.
For the narrow web flexo market, the product name is Helios, and it can handle a sheet size up to 28” x 47”.
DLE systems have advanced software that allows the user to define parameters that control the formation of the image – especially in the z-axis – “on the fly” during the engraving process. These parameters cause the laser to custom-shape the dot support structure for optimum printing results. For example, a plate can contain highlight dots with a wide, sturdy support base while the same plate has shadow dots with little or no support. “This feature allows good support of highlights while maximizing the reverses in the shadow dot regions to maintain full tonal range,” says Ed James, laser product manager for Stork Prints Austria. “The software automatically interpolates the dot support shapes between the two extremes, which are operator defined (Figure 1). DLE also has the unique ability to produce below-the-surface highlight dots. Since the dot height can be calibrated for a specific press setup, this ability allows the printer to use the impression needed for printing good solids while avoiding dotgain in the highlights.” (Figure 2)
The Helios DLE system can also engrave flexo sleeves, 2D/3D embossing plates or sleeves, and Stork RotaMesh and RotaPlate screen products.