Digital Press Technology - Part 2: Production Inkjet Printing

1. Digital Press Technology - Part 2: Production Inkjet Printing Inkjet printing is a versatile, non-contact printing process in which different sizes and colors of ink droplets are formed and sprayed at high speeds in precise, computer-controlled patterns from tiny nozzles on a moving or stationary printhead. Over the past 20 years, the inkjet printing process has been adapted to replicate and expand the capabilities of offset, flexographic, screen, gravure, and pad printing processes. Production inkjet printing ​typically refers to high-speed, single-pass inkjet printing systems that supplement web and sheetfed offset printing presses. Production inkjet presses enable print shops to fulfill the growing demand for longer runs of jobs that involve variable data or fast-turnaround short-run jobs. Commercial printing companies and in-plant print shops use inkjet presses to produce financial statements and bills, direct mail, books, magazines, catalogs, and some types of indoor display graphics and folding cartons. Specialized single-pass inkjet presses have been developed to digitally produce labels, envelopes, photo book pages, textiles, and corrugated for packaging and displays. Some shops have replaced an aging offset press with a production inkjet press. Other production inkjet presses have been installed to replace slower ​electrographic digital presses​. Companies that make different types and sizes of production inkjet presses include HP, Canon, Ricoh, Xerox, Kodak, Fujifilm, Konica Minolta. Riso, and Screen. How Production Inkjet Printing Works Production inkjet presses are ​single-pass inkjet printers. ​These printers use fixed arrays of industrial-grade printheads that span the full width of the substrate. All ink colors are laid down

2. as the substrate feeds through the press at speeds of up to 600 ft. per minute for four-color pages and up to 1,000 ft. per minute for black-only pages. These print speeds are much faster than multi-pass (“scanning”) inkjet printers in which printheads travel back and forth across the width of the paper. ​From the outside, many production inkjet presses look big, mysterious boxes. This video “Inside the Xerox Trivior 2400, explains some of the processes that go on inside. (YouTube Video: Inside the Xerox Trivor 2400 Press​) Production inkjet presses use papers and paper feeding and handling systems similar to those built for offset web or sheetfed presses. Onboard drying systems evaporate the water from the inks before the printed pages are coated, cut, and stacked. Each press requires a powerful digital front end that can store and quickly process the high volume of data required to set up a steady stream of jobs that involve thousands of personalized letters, transactional statements, and direct mail pieces. Spectrophotometers and quality inspection systems are included in some inkjet presses to adjust for failed nozzles or detect and resolve other problems that could affect the overall look of the printed pieces. Types of Production Inkjet Presses Because production inkjet presses can cost more than a million dollars, some are designed to be upgraded on site as better printheads, inks, and new features become available.

3. Monochrome presses ​use black ink to print text-only documents such as books, manuals, package inserts, and billing statements. Color presses use CMYK inks to print magazines, catalogs, book covers, and other materials that feature brand graphics and full-color images. Web Presses feed large rolls of paper through the press at high speeds. Wide-web presses such as HP’s 42-inch.PageWide T400 HD can print 8700 full-color pages per minute (or more than 500,000 pages per hour). The HP T400 can also print rolls of indoor advertising posters and banners up to 108 in.long. The HP PageWide product line includes large, industrial inkjet web presses that can produce millions of impressions each month. (Video: ​HP PageWide T400 Web Press​) Continuous Feed Presses start with rolls of paper but may generate ready-to-bind or ready-to-mail pages. For example, Konica Minolta’s WEBJet™ 200D enables can continuously

4. print (simplex or duplex), cut, perforate, slit, merge and stack printed pieces all in one machine. This video shows how a continuous-feed press works and some of the variable-data applications that can be produced at high speeds. (Video: ​RICOH Pro VC60000 Continuous Feed Inkjet Printer​) Cut Sheet Presses start with pre-cut sheets that can be cut, trimmed, folded, perforated, or hole-punched to make products such as tickets, brochures, or wire-bound manuals. These presses are built to handle a wider range of paper types, thicknesses, and textures than web presses. Some sheetfed production inkjet presses can handle sheets up to 23 in x 29.5 in.

5. This video shows the Konica-Minolta Accurio-Jet KM1 sheetfed press works and how it is used by the printshop Postcard Mania: Video: ​Konica Minolta Accurio Jet KM-1 Inks Most production inkjet presses use water-based pigment or dye inks. The primary exception for commercial printing is the Konica-Minolta Accurio-Jet KM-1 sheet-fed press that uses UV-curable inks. Substrates While production inkjet presses are designed to complement offset presses, the water-based inks used by most inkjet presses soak into the fibers of uncoated offset papers. This makes the colors look more muted than pages printed with oil-based inks on an offset press. Plus, the water-based inks don’t always adhere well some glossy coated offset papers. To alleviate these issues, some production inkjet presses can apply primers to uncoated or coated offset papers before printing. Plus, UV-curable or aqueous coatings can be applied to printed pages to replicate the look and feel of offset prints and protect the prints from damage during finishing and mailing. As production inkjet printing has grown in popularity for applications such as direct-mail or books, some paper manufacturers have developed “treated” papers optimized for high-speed inkjet printing. During manufacturing. these papers receive additives that keep the ink pigments close to the surface of the printed sheet. This helps improve the vibrancy of the colors.

6. Because the Konica Minolta Accurio Pro KM-1 Pro uses UV-curable inks, it can print on coated and uncoated offset sheets without primers as well as textured papers, weather-resistant synthetic papers for simple signage, and paperboards for folding cartons. Prepress and Makeready Production inkjet printing eliminates the need to clean an offset press and mount new plates each time one print job ends and the next one begins. Highly automated workflows capitalize on the ability to schedule and produce a high number of short-run jobs during an eight-hour shift. Automation also reduces the risk of errors caused by quickly producing a steady flow of short-run jobs and the need for highly skilled press operators. To minimize human touchpoints, the digital front ends of inkjet production presses are typically designed to exchange data with automated systems for designing, ordering, proofing, scheduling, color managing and finishing all jobs that a print shop might receive. The software has also been developed to automatically arrange (“impose”) multiple page files on large press sheets to ensure that all pages in a multi-page publication will appear in the proper sequence when the printed press sheets are folded, cut, trimmed, and bound. For example, EFI Fiery digital front ends for production inkjet presses combine fast file processing speeds with tools that manage color, optimize image quality, and impose pages. EFI Fiery servers connect with EFI’s own web-to-print and business management software as well as prepress automation software from Agfa, Esko, Screen, and Kodak that prepares jobs for production on a combination of ​digital printers​, ​offset​ or ​flexo presses​, and finishing equipment. Finishing Current owners of offset presses want to be able to use some of their existing cutters, trimmers, folders, and coaters with sheets produced on production inkjet presses. New users of production inkjet printers can choose either online or offline finishing equipment, depending on whether they want to use the production inkjet printer to create a single type of product (such as books) or shorter runs of multiple types of products. Finishing equipment includes: ● ● ● ● ● ● ● Stackers to collect and bundle printed pages so they can be finished and bound properly Cutters to convert large printed sheets into tickets, postcards, flyers, or book pages Coaters for applying aqueous or UV-curable clearcoats Die-Cutters to change the shape or functionality of printed elements. Perforating devices to create easy-to-tear-off coupons, payment stubs, or order forms. Punching equipment to make holes for three-ring binders or spiral binding. Folders to convert a large printed sheet into envelope-ready letters or brochures

7. ● ● Binding equipment to attach pages of books, catalogs, and magazines together Three-knife trimmers for bound books Inkjet-enabled “digital embellishment presses” eliminate the need for printers to buy specialized equipment for embossing, foiling, and spot varnishing. Companies such as Scodix and MGI make presses that apply surface textures, metallics, holographic effects, or glitter to specific areas of an image. Advances in Technology Since the first web-fed production inkjet printers were introduced in 2008, the print quality, reliability, media versatility, and color consistency of production inkjet presses has steadily improved. Still, most production inkjet printers are used primarily for applications that use light to medium ink densities on the coated and uncoated papers traditionally used by offset presses. Expect continuing innovations in inks, color gamuts, color management, automation, and efficiency, For example, the new Xerox Baltoro HF inkjet presses use new High-Fusion inks to print on a variety of offset-coated stocks without primers. The Fujifilm J Press 720S has integrated controller with advanced color calibration capabilities that maximize color consistency without excessive press operator intervention or expertise. Cloud-based print-shop workflow management systems are making it possible to oversee the efficient and cost-effective production of all incoming jobs, whether the job will be produced on an analog or digital press. Artificial intelligence can help print shop owners determine the best combination of printing and finishing equipment to meet each client’s deadlines, budget limitations, and quality expectations. The next flurry of innovations in production inkjet printing is likely to be introduced at the drupa 2020 international print show in Dusseldorf, Germany next summer. Follow Us on Social Media This post is part of a series we are publishing to help you understand the many types of analog and digital printing processes now in use. Our next post discusses wide-format inkjet printers. Follow Ordant on ​LinkedIn​, ​Facebook​, or ​Twitter ​to learn when the next post in this series has been published.