The author has already posted 2 Flexographic printing related articles on this blog. The first one was “Developments in flexo printing and label production technologies” https://www.labelsandpackagingworld.com/2020/10/developments-in-flexo-printing-and.html and the second one was based on a successful entrepreneur Deepanshu Goel of Creative Graphic Solutions Private Limited who has established Prepress and Photopolymer plate making units around the country. https://www.labelsandpackagingworld.com/2020/11/creative-graphics-service-to.html . Deepanshu Goel has cooperated in putting together this article by providing necessary inputs on flexo prepress and Photopolymer plate making.
· Exposure units
- structural design of boxes, flexible packaging or other specific shapes.
- integration of graphic and structural design.
- prepress functions: image retouching, color management, plate preparation, content management and control, printing or finishing specific preparations like screening or registration marks;
- process management functions: automation of prepress functions and the prepress workflow;
Esko’s portfolio encompasses digital flexo solutions from narrow-web label printing to wide format corrugated printing. The range of CDI computer-to-plate imagers offers high quality and productivity for digital flexo platemaking for all markets and applications. Karan further adds, “With complete portfolio of Packaging Management software, Packaging Design software, Packaging Prepress software & Automation software strongly integrated with Esko CDI Spark & Crystal range of Flexo plate imaging products, we can proudly state that over 80% of all digital Flexo plates worldwide are produced with Esko technology. Esko’s developed technologies like HD Flexo, Full HD Flexo, Crystal CDI, Crystal XPS UV LED Exposure are driving high level of quality and consistency in Flexo printing for various applications”.
Miraclon is the new home of Kodak Flexcel Solutions. Miraclon is fully focused on the development, production and sale of Kodak Flexcel technology. This includes the Flexcel NX Imager and the Flexcel NX Laminator which form the equipment component, along with the consumables. Explaining their process Hersh Lulla Marketing Manager, Asia Pacific Region; The flexo plate-making process when utilizing Kodak Flexcel Solutions in pre-press includes:
- The 1-bit TIFF file is prepared, at which stage the pre-press operator selects the right Digicap NX pattern (proprietary Miraclon technology) which allows for higher densities and optimum ink laydown.
- The file is then sent to the Flexcel NX System, which outputs the file on the Thermal Imaging Layer (TIL) utilizing Kodak SQUARESPOT imaging technology. The TIL is a uniquely designed film that provides rapid, high-resolution imaging for true 1:1 dot reproduction.
- This Thermal Imaging Layer (TIL) is then laminated onto the Flexcel NXH photopolymer plate using the Flexcel NX Laminator. This lamination process eliminates oxygen from plate exposure and creates higher-performing plates that hold stable and consistent dots. This is a patented technology process.
- The laminated TIL-NXH is then main-exposed with UVA light.
- The exposed, delaminated NXH plate is then put through processing, drying and light finishing (under UVC lights) to complete the plate-making process.
Kodak Flexcel NX Solutions simplifies the overall plate-making process while offering significant productivity and image quality benefits. Consistent plate-making and accurate image reproduction mean fewer plate re-makes in pre-press, while also enabling a much higher level of sustainability on press by reducing start-up wastage and ink consumption through optimized ink laydown to achieve higher densities.
According to Deepanshu Goel of Creative
graphic Solutions explaining the process employed by them, similar plate making
equipment is offered by suppliers like Flint, Kodak and Dupont. First with help
of special flexo prepress software from Esko one has to do all as mentioned
above up to color management. Then with the special imaging engine they rip the
file into pixels, then these pixels are imaged on a Dupont, Flint or kodak
plate depending on the machine. There are different processes in use now to produce a
photopolymer flexo plate. These are as follows:
- Analog aqueous, or water wash: Plates using a negative to expose on the plate exposure and wash using a water system.
- Analog solvent wash: Same as above but using a solvent wash.
- Digital ablation aqueous: LAM (Laser Ablation mask) Plate is exposed with an electronic image sent through a laser ablation unit, which ablates a plate covered with an aluminum mask. Followed by UV exposure and water washing.
- Digital ablation solvent: Same as above that the plate is covered with Carbon and washed with solvent.
- Digital ablation thermal: Digitally ablating the masked plate, exposing to UV and finished in dry thermal processing unit.
- Digital laser engraving: Laser engraves complete image into exposed plate or sleeve.
He further explains that the LAM plate is imaged in the CDI engine and this image is exposed on the plate and the exposed part is polymerized by UVA light action. While the exposed portion gets polymerized, the unexposed portion is washed off in washing equipment with different chemicals, dried then given de-tacking with UVC machines. One plate takes minimum 2-3 hours to make. Plate has drying time of 90-120 minutes depending on plate thickness and plate size. From receipt of artwork to plate delivery is about 12 hours.
Evolution and changes keep coming to flexo printing like flat top dots, changing polymers for different surface tension enabling better transfer of different inks and different shore hardness. The plate manufacturers keep altering the chemistries of the plate materials to achieve improved printing. Improving imaging is also an ongoing process, especially with small pixel size by altering the shape of dots. Changes are taking place with RIP engines to achieve different dot shapes and angles to get a better transfer and get a sharper image. So, depending on the targeted quality of image different dot size and shapes are made.
Flexo has prospered due to ease of use and cannot be really compared to other technologies as all have their own advantages. It makes converting much easier with in line converting. With the advent of UV inks, quality of flexo has come closer to offset with higher LPI, however with lower consumption of ink, higher densities, printing half tones, offset still has a better edge. The constant evolution of flexo has enabled the gap to be narrowed and the print quality is now becoming the preferred one universally.