To help keep them competitive, printing equipment manufacturers are developing presses that not only run more efficiently but also maintain or improve print quality. At the heart of the new presses are automation tools such as servos and the latest in software engineering, which together boost efficiency and productivity.
Fast changeover and reduced waste are fundamental themes driving these equipment design choices. Increased concern about the environment is starting to make an impact on press operations and design, as well.
Here’s a look at how the major printing technologies-flexography, digital printing, screen printing, offset lithography, rotogravure and combination printing-are helping flexible packaging converters serve their customers better.
FLEXOGRAPHYFlexography continues to tighten its grip on flexible package printing as hardware and software improvements drive better print quality and consistency. Flexo make-ready is becoming more efficient, too, which reduces downtime and materials waste.
“Flexo has traditionally been the low-cost producer of packaging, and the print quality wasn’t as good” as that of other printing methods, says Bill Pope, technical director at the Flexographic Technical Association (FTA).
But “flexo printing has seen a sharp upturn in quality in the past five years,” he adds. “Nowadays flexo is doing some high-end work and can compete right next to offset and gravure, no problem.”
The reasons relate to improvements in the components of flexo presses, including plates, anilox rolls and the screening algorithms in the software guiding the presses. Improved consumables also are boosting print quality. These include faster-curing inks and substrates with surface characteristics that are more conducive to flexo printing.
Further, “Better tools and devices have been added to flexo presses for inline monitoring of color control and registration. Those can help produce less waste, increase speed and reduce make-ready,” says Bill Hickey, president of the Smyth Companies Inc. and chairman of the board of directors of the Label Printing Industries of America (LPIA).
Servo technology is making strong inroads on flexo presses, with converters reaping the benefits of greater press efficiency and improved print quality.
Aquaflex, for example, has combined servo and sleeve technology on its ELS-D Series of flexo presses. This series of presses features dual-axis servo-driven print heads and cantilevered sleeved plate cylinders. The presses, engineered to run thin films, provide gearless infinite repeat capabilities and automatic registration at significantly less cost than existing systems, according to Aquaflex.
The ELS-D presses are compatible with 16-, 10- and 13-inch web widths, and applications include labels and narrow-web flexible packaging converting. The abilities of the presses came to the fore in an experiment the manufacturer conducted for a customer.
In the test, bearer bars were eliminated from a narrow web substrate and the job was run through the press. Even without the bearer bars, which typically are used for accurate plate mounting, registration and quality control, the press made a consistent impression-with no shadowing on a 20% half-tone printed beside a series of solid lines. The combination of servo technology and the software controlling the press gets the credit for this performance.
A new sleeve flexo press from Windmöller and Hölscher (W&H) also incorporates automation and innovative engineering to deliver high print quality and ease of operation. W&H’s Miraflex C direct-drive sleeve flexo press features a sleeve-type nip roller located before the first printing deck, which makes it quick and easy to change the nip roll from film to paper or to tube production, giving converters greater flexibility in the jobs they can run on the same press.
The Miraflex C press can be customized using automation modules that reduce make-ready times and print waste. W&H’s automatic Easy-Set impression setting system, Easy Reg register-setting system and Turboclean ink supply and wash-up system also are available as options.
The Mark Andy XP5000 press also leverages servo technology for narrow-web flexography, to deliver high productivity and rapid changeover. The fully electronic, shaftless servo design of the XP5000 press reduces process variation and print defects by reducing vibration, controlling web tension and creating intelligent pre-registration with precise servo plate roll positioning. Proprietary software algorithms reduce set-up by speeding up pre-registration.
The XP5000 press also offers converting flexibility. It can be outfitted with a variety of printing technologies, including ultraviolet (UV) or water-based flexo, rotary screen printing, hot/cold foil decorating and ink jet printing for variable data. Each print technology is interchangeable among any of the 12 print stations (maximum) on the press.
The issue of environmental friendliness also is shaping the flexo segment. In this category, Sun Chemical Corp. has developed its WetFlex wet-on-wet flexographic printing. This process uses specially designed or retrofitted flexo presses and Sun’s UniQure inks. The inks are wet trapped using a central impression cylinder press and cured via exposure to an in-line electron beam at the end of the press.
The UniQure inks are made without using volatile organic compounds (VOCs) and the inks contain no solvents, so environmental impact of the WetFlex process is minimal compared to printing with solvent-based inks.
Also enhancing the WetFlex system’s green profile is the lack of interstation drying of inks, which reduces energy use. “It really is the ultimate in green technology,” says Michelle Hearn, director of marketing, North American Inks, Sun Chemical.
The process, which results in negligible ink migration, was designed for use on food packaging. Applications include frozen food bags and lidding materials; flexible aluminum lids currently are being printed using the technology in Europe.
Complementing its green attributes, the WetFlex technology reportedly delivers better print quality and color reproduction than regular flexography. “The print fidelity is similar to rotogravure quality in some applications, even for flexible materials,” Hearn says.
Another food-packaging flexo project, announced at drupa 2008, is “UV Flexo for Food Packaging.” This joint project of Gidue, Air Liquide, IST Metz, Softal and Sun Chemical aims to offer a one-stop solution for printing safe, cost-effective flexible packaging for food.
The solution uses Gidue’s Athena servo-controlled, mid-web flexo press, which has gained a reputation for quality and productivity in UV flexo printing. The press integrates in-line plasma treatment for film substrates, which greatly increases the adhesion of UV-curable inks to flexible packaging materials.
Also integrated into the press is a compact UV dryer that provides nitrogen-inert UV curing. The low-migration UV flexo inks used on the press, supplied by Sun Chemical, minimize migration of ink components without sacrificing print productivity and quality.
DIGITAL PRINTINGFor narrow-web flexible package applications such as labels, shrink sleeves and pouches, digital printing continues to make inroads. Although line speeds are significantly slower than what can be achieved with flexo and rotogravure, ink jet and toner-based digital printing is attracting flexible packaging converters for several reasons.
First, digital printing eliminates make-ready time and materials waste, which makes it economical to run small to medium-size print runs. Print quality is good, and small jobs can be turned in a single day. Because digital print jobs go straight from the computer to the print head, with no need for plates or an impression device, time-consuming tasks such as plate making are nonexistent.
Digital equipment also can be used to print variable data such as bar codes and serialization codes, and the technology enables production of custom versions of packages for different geographic locations, languages and promotions.
Technology advances in equipment and consumables have fueled improvements in the quality of digital printing in the past several years. Industry observers say digital’s quality now rivals that of flexo and even offset printing.
“On the high end of ink jet printing, you can see no difference from a photograph,” says Dan Marx, vice president, markets and technologies, Specialty Graphic Imaging Association (SGIA). Inkjet “has been at flexo’s door for a while. As the speed of digital printing continues to come up, I think it will start knocking on that door.”
The reasons for the improvement in ink jet print quality relate to the development of:
• Pigmented ink suited to ink jet delivery. Pigmented inks enable color matching, which the dye-based inks previously used for ink jet printing did not.
• Substrates with ink jet-receptive coatings.
• Raster image processor software that provides color management.
• Greater processing power in the computers driving ink jet printing.
• Affordable automatic spectrophotometers that dramatically reduce the time required for color measurement, an essential component of color management.
With this combination of developments, “Ink jet hit the perfect storm in the last five years and really started being accepted,” says Richard Black, director of digital solutions at All Printing Resources Inc.
Although digital printing is competitively positioned vis-à-vis flexography based on print quality and cost-particularly for small runs-digital printing still lacks the speed of other printing methods. The latest narrow-web ink jet systems run at 80 to100 feet per minute.
“All they have to do is increase the speed to make significant inroads into a very entrenched marketplace,” Black says. “It’s a tsunami waiting to happen.”
Ink jet technology also is finding a niche in proofing. All Printing Resources recently introduced its DLP3 system for digital proofing, printing and production.
Using the system, label proofs can be laminated and digitally die cut without creating an actual die. Proofs can be color managed to match the converter’s flexo press, should it be desirable to print a longer run of the same label via flexo. The DLP3 system also can be used to print and finish short runs of labels and to create mock-ups.
The DLP3 system uses piezo-electric ink jet heads, with an Epson 4880 ink jet printer as the print engine. Piezo-electric technology uses electrical signals to trigger the ejection of ink droplets onto the substrate.
Piezo-electric technology is finding acceptance for production-oriented, narrow-web, UV ink jet printers. Specifically, the Jetrion 4000 UV Ink Jet System from EFI and the SolarJet UV printer from Sun Chemical incorporate piezo-electric ink jet heads supplied by Xaar.
The SolarJet system targets the pharmaceutical, health and beauty, industrial, electronics and fast moving consumer goods (FMCG) markets. Digital printing is suited to these applications because graphics and text on the labels are frequently updated, necessitating shorter run lengths. The system can achieve an apparent print quality of 900 x 900 dots per inch, according to Sun.
The Jetrion 4000 system was developed for applications such as labels, tags, forms and tickets. EFI claims the Xaar print heads on the system provide near-photographic quality, with print resolution of up to 1,000 dots per inch.
EFI recently added pre-die cut label printing functionality to the Jetrion 4000 system plus variable data printing, including one- and two-dimensional bar codes and variable text, numbers and graphics. For security applications, the Jetrion 4000 system can print using invisible inks and taggants.
In the world of toner-based digital printing, Hewlett-Packard (HP) continues to enhance the HP Indigo presses. Offering the same kinds of production benefits as ink jet printing, the electrophotographic technology driving the HP Indigo equipment can perform 7-color process printing and the Pantone-licensed spot-color printing required by leading brand owners.
HP currently is taking orders for the new HP Indigo WS6000 Digital Press, with deliveries to start in February 2009. This model prints at 98 feet per minute in four-color mode. It will be suited to longer print runs than current electrophotographic presses, providing cost justification on jobs up to 13,000 feet.
HYBRID/COMBINATION PRINTINGWith fierce retail competition driving consumer goods companies to design ever more eye-catching labels, opportunities are quickly expanding for hybrid, or combination, printing.
In some cases, special functionality can be added to an existing press. The EFI Jetrion 3025 ink jet printer, for example, can be added to an offset press to print variable data to the offset-printed labels.
Some press manufacturers are focusing on modular presses that allow for flexible combinations of printing and finishing techniques. Gidue has developed the Xpannd hybrid flexo/offset/silkscreen press, with up to 13 inline stations.
This hybrid press addresses the need for the all-in-one-pass, inline printing that is common in wine, oil, food and cosmetics label printing. The Xpannd press is designed for maximum efficiency in short runs, within a standardized offset job flow.
Others with hybrid solutions include:
• Drent Goebel, which uses modular construction for its offset presses to provide the option of technologies such as rotogravure.
• Muller Martini, with the Alprinta-V web offset press, which offers the flexibility of flexo and rotogravure printing in addition to offset.
• Gallus Inc., whose Gallus EM 280 press combines flexo, rotary screen printing, hot stamping, cold foiling, embossing and other converting processes on one piece of equipment.
SCREEN, OFFSET AND ROTOGRAVURE PRINTINGLike other types of printing systems,screen printingequipment is becoming more efficient thanks to designs that feature servos and programmable logic controllers and custom software.
In screen printing, these design features save time by automating tasks such as squeegee positioning. Waste is reduced and efficiency improved, because the automatic adjustments are faster and more precise than if operators performed them manually.
The partnership of Spartanics and Systec has engineered fully electronic controls into the Spartanics-Systec Fineprint Flatbed Screen Printing Line, which uses roll-to-roll screen printing technology to print UV- and chemical-resistant labels, transfers for printing packaging, high-end cosmetics labels and other types of labels and packaging.
Job set-up on the Spartanics-Systec system is executed with a few keystrokes, and a high-precision servo drive motor for the squeegee assembly enables high-quality printing for small images, with a minimal gap between first and second prints.
The algorithms in the equipment’s software and the redesign of squeegee assemblies and screen holders enable precise registration of the substrate and automatically compensate for screen stretch.
Foroffset lithography, the use of inexpensive sleeves on press has opened up new flexible package converting opportunities. The Variable Sleeve Offset Printing (VSOP) press from Drent Goebel enables printers to quickly, easily change over to a different repeat length by changing two lightweight sleeves.
Thus changeover time and cost is minimal versus changeover on a conventional offset press, and production flexibility is much better, too. According to Drent Goebel, print quality on the VSOP press is comparable to rotogravure printing. The equipment can be used for applications such as roll-fed labels, shrink sleeves and roll-on, shrink-on labels that require high-quality graphics.
Another offset technology, waterless printing, continues to attract users that need high-quality labels and want to reduce waste. Waterless printing is a process that eliminates the dampening system used in conventional offset lithography. It uses a special silicone rubber coated printing plate, specially formulated ink and a system for temperature control on press.
The acceptance of waterless printing has been “pretty enthusiastic in the wine-label printing industry and for food-package labels, mostly because of its ability to render high resolution and the ease of handling artificial substrates” plus waste reduction, says Arthur Lefebvre, executive director and founder the Waterless Printing Association.
Waterless printing is compatible with a greater range of substrates than conventional offset printing, and make-ready is faster. Although waterless presses are not generally available, virtually any offset lithographic press can be retrofitted to run waterlessly.
Waterless printing provides environmental advantages, as well. The process eliminates the VOCs used in dampening and the toxic substances found in blanket wash solutions.
Further, waterless presses come up to color and register faster than conventional presses and print more consistently, so paper waste is greatly reduced. This provides environmental and economic benefits for printers, as does the water conservation inherent in the process.
Rotogravureequipment manufacturers, like their competitors, are flexing with the times, providing equipment suitable for small to medium-sized print runs at a lower price than conventional rotogravure presses.
An example is the Heliostar S rotogravure press from W&H. This press features synchronous digital drive technology that enables the converter to register a print job within one web length, minimizing start-up waste and accelerating set-up.
All Printing Resources
Drent Goebel USA
Flexographic Technical Association
Label Printing Industries of America
Specialty Graphic Imaging Association
Waterless Printing Association
Windmöller and Hölscher