By Olivia Cahoon
Printing on corrugated board is a growing interest for print service providers (PSPs) entering package printing. Currently, there are two types of methods for corrugated printing with digital technology—pre-printing (see sidebar) and direct printing. In this article, we discuss direct printing onto corrugated board.
Direct printing with digital flatbed devices is commonly used for prototype creation. Flatbed vendors address challenges for direct printing onto corrugated board with load/unload mechanisms, color gamut, image quality, and material hold down to entice PSPs to utilize their newest digital technologies over analog.
Digital printing on corrugated board entices PSPs to leave behind traditional analog systems for a number of reasons including short-run capabilities, faster turnaround times, and expanded offerings. Wthout the need to change plates for file change digital quickens the entire order process.
Avoiding makeready allows print providers to go straight into production, increasing the ability for display, packaging, and temporary manufacturers to create prototypes and respond to clients’ demands. Patrick Donigain, specialist and marketing senior, Canon Solutions America, believes that efficient production of variable data and image packaging offers new short-run opportunities that can be highly lucrative.
Transitioning to digital printing for corrugated board comes down to return on investment (ROI). “Digitally printed board is more economical—at certain run lengths—then running the same job on a corrugated press,” says Larry D’Amico, direct of sales, Durst Image Technology US, LLC. The cost of offset or flexographic plates that require press makeready time compared to digital alternatives can be financially favorable for a short-run job.
According to Michael Maxwell, senior manager, Mimaki USA, Inc., the volume of corrugated boards printed in an analog environment can exceed the benefits of digital, however, small runs and prototyping are better served through a digital process. “By assessing the cost-effective quantities for digital versus standard processes, print providers can serve customers in both areas for short and long runs,” he advises. In addition, improvements in printing processes like LED curing make it possible to adopt digital without concerns regarding heat.
Concerns for Corrugated
While digital printing to corrugated board offers a higher ROI with fast turnaround times, it is still a developing technology. However, flatbed device manufacturers offer solutions to address challenges.
Corrugated board doesn’t lay flat because it is a naturally inconsistent surface, which is sensitive to heat. This is a concern for equipment with printhead technology millimeters from the substrate and must be overcome during loading, imaging, and unloading. Load/unload mechanisms like suction cups, skis, and vacuums offer a solution to secure the corrugated material.
Becky McConnell, product marketing manager, graphic systems division, Fujifilm North America Corporation, believes that because board distortion can happen due to the nature of manufacturing, it’s critical to have a material handling system that not only manages to move sheets from one point to another, but also doesn’t damage the board or flutes in the process.
Fujifilm’s Inca Onset X Series of printers features a dual or single robotic handling system for handling corrugated boards and is fitted with an appropriate specialized head effector. “The head effector features suction cups that are distributed equally over vacuum bars on the underside of each head effector, and they enable substrates to be loaded and unloaded reliably,” says McConnell.
The Inca Onset X Series can be purchased or upgraded to speeds from 2,000 to over 10,000 square feet per hour (sf/h). Fujifilm also offers the Acuity F flatbed with a High Flow Vacuum to hold corrugated boards that produces just under 1,700 sf/h.
Durst printing systems offer a combination of tools to lay corrugated board flat. “Our skis are pneumatically controlled and digitally positioned. We offer three different levels of ski material depending on the flute thickness,” shares D’Amico. Its systems also include 12 individual vacuum pumps to provide power and control while eliminating the need for taping. The Durst Delta SPC 130 prints on corrugated up to 100,000 sf/h.
While options for load/unload mechanisms exist in the corrugated market, some prefer a hand-feed approach, better suited for lower volumes. “Feeding by hand, our changeover from job to job is a few seconds. Our customers prefer to not have the additional setup time that is required with most feeders and stacking mechanisms,” explains Mark Swanzy, COO, Xanté Corporation.
Oversized tables with multiple origin points aid operators that manually load/unload corrugated board. Maxwell says Mimaki’s JFX200-2531 offers an oversized table with multiple origin points to improve the time between prints by enabling operators to prepare a job in one print zone while a different job is printing in the other print zone. Mimaki’s printer speeds for corrugated range from 250 to 600 sf/h.
In the packaging segment, it’s integral to achieve a wide color gamut with low ink consumption. ICC compliant color profiles optimize color gamut. Eric Carlomusto, inkjet demonstration manager, Agfa Graphics, says users can emulate Pantone libraries the majority of the time. Agfa’s Jeti Tauro prints corrugated board at speeds of 1,485 to 2,960 sf/h. The UV ink creases printed media without cracking. It’s capable of 200 percent stretch—flexible for most corrugated applications.
Extra ink channels are also used for better print quality at high speeds. For example, Donigain says white ink for specialty applications allow presses to achieve a large color gamut on standard corrugated materials. Ink channels that support light cyan and light magenta also allow for smooth print quality.
“White ink capabilities are important for vibrant colors or brand color matching,” explains Mark Schlimme, direct of marketing, Screen Americas. Corrugated board is absorbent, which can affect color and the show-through of the fluted surface. Flood white or white layering can be used as a base or to enhance the final color. However, he cautions that white ink is expensive, even compared to a paper-lined board.
Image quality and resolution is higher on white coated board than uncoated boards. “Uncoated brown corrugated board has a much smaller gamut because of the white point and ink absorption,” says Ken Parsley, product manager, Mutoh America, Inc. The Mutoh ValueJet 1638UH has a top speed of 220 sf/h and a media retaining system standard to assist with difficult media.
High-quality litho-like print quality requires a white top, kemi-board, or kraft liner board. Schlimme recommends only printing directly to kraft or virgin paper surfaces for lower quality, lower resolution applications. Additionally, unlined or uncoated kraft boards don’t support high-resolution printing, fine lines, or small text.
Smaller text can be problematic on flexographic presses with ink bleed, plugging, and a lower LPI screen. “Our print quality is up to 1,600×1,600 dpi, which is printed with a 1.2 picoliter dot and allows for detailed graphics and small point text,” says Swanzy. Xanté’s press speeds are dependent on sheet size—24×28-inch sheets print up to 3,328 sf/h while 48×96-inch sheets print at up to 7,872 sf/h.
The desired image quality also affects the press’ print speeds. Schlimme explains, “while Screen’s Truepress Jet W3200UV HS can print excellent process color image quality to kemi-board at speeds over 1000 sf/h, it’s realistic to expect that the physical handling requirements will limit an operator to something between 800 and 1,000 sf/h.”
According to Donigain, six to 42 picoliter droplets and active pixel placement compensation assures image sharpness, density, and uniformity around the entire flatbed.
Material Hold Down
Flatbed presses with industrial strength and zone vacuum beds hold boards in place for printing. “If the corrugated boards are exposed to variable humidity or changing temperature, however, the board can pop and buckle,” explains Schlimme. He suggests a higher quality board to eliminate the need for tape down.
Other solutions to hold down corrugated boards include vacuums. Donigain says for short-run corrugated packaging and temporary point of purchase (POP) displays, vacuum configurations allow for dynamic, versatile large format printing applications. The Canon’s Océ Arizona 6100 Series features a High Flow Vacuum system that handles warped corrugated boards and plywood sheets without tape or physical means to hold boards down. Canon’s press speeds for corrugated boards range from 200 to 1,000 sf/h.
While vacuum belts are used to help warped boards lay flat and feed smoothly through the printing path, Swanzy warns that corrugated warp can be much more problematic with digital printers compared to flexographic presses. Pinch rollers and vacuum belts should use low pressure to avoid crushing boards. He explains, “corrugated crush can affect the structural integrity and is a concern on most corrugated flexographic presses, which can be difficult to control.”
According to Roger Walkley, product manager, Inca Digital, mechanical systems that push boards down risk injury to the machine as well. “Without sufficient vacuum the board can pop up, damaging an unguarded system,” he says. Flatter boards present fewer problems for mechanical intervention. The Inca Onset X3 prints up to 9,688 sf/h while the Spyder X prints 1,615 sf/h.
Package printing includes prototypes, packages, and POP standees. It also correlates with food-related applications, which hold specific requirements for ink. According to D’Amico, the application, smell, or chemical composition of digital ink may make it unusable for food applications. Aqueous-based inks eliminate the smell associated with UV inks. “We are looking at low migration inks suitable for digitally printed boxes that come in close contact to food,” he adds.
Print providers that intend to offer packaging for food products must ensure the ink doesn’t contain UV reactive chemistries. To find ink formulations, print providers can use material safety data sheets provided by inkjet press manufacturers.
Due to various paper layers and moisture in the material, printing to corrugated board is a heat sensitive process. LED curing systems reduce the heat to stabilize the shape and dimensions of the material while conventional systems omit heat. “swissQprint offers a new LED curing system that reduces the heat dramatically,” says Carmen Eicher, VP of marketing, swissQprint.
swissQprint printers are intended for small outputs in the corrugated industry. Despite being capable of 2,217 sf/h, Eicher says the performance in the corrugated sector realistically starts at 1,100 sf/h in production mode to produce adequate quality. In quality mode for high-quality results, the output is about 600 sf/h.
The Future of Corrugated
While digital flatbed devices offer a number of benefits to print providers, traditional analog still tends to be a more favorable option. Parsley explains that while high-end machines have the production capability packagers need; there is room for improvement in ink for image quality on uncoated stock.
Donigain believes digital’s print quality surpasses analog quality for low- and mid-volume production, but achieving high levels of quality at analog print speeds is difficult and represents an area for improvement. However, speed is expected to improve as single-pass technology advances.
D’Amico also sees one-pass technology entering the market with speeds ten times or more what the scanning systems produce. Once these products become widely adopted, he believes they will make a significant impact on the corrugated market.
Preparation and Trends
Before purchasing equipment, print providers should fully understand the work they are producing to obtain the technology that best fits those applications. This includes understanding the entire workflow—how the files are received and how the boards are finished. “It is critical that all phases of producing the work must be understood before you consider a digital printer,” says D’Amico.
Schlimme agrees and says that finishing and delivery of printed boards is critical. “Wrapping and packing 1,500 brochures or sell sheets in a box is a very different task than staging even 25 sets of POP standees or ready-for-retail pallet wraps,” he explains. In fact, poor handling during wrapping, packing, and shipment can ruin print jobs if large materials are mishandled or improperly stacked.
Ready-for-retail packaging is becoming more relevant as big box retailers seek more localized and regionalized products. This creates a need for shorter runs. “It’s becoming increasingly important to offer services and solutions across the full spectrum of a product’s branding,” suggests Schlimme. Print providers with clients who already request small format folding carton packaging or labels can offer clients ready-for-retail packaging or in-store standees and displays.
But retail packaging isn’t the only market taking advantage of short-run printing. Eicher points out that designers and marketing agencies prefer seeing and touching mock-up samples rather than 3D CAD simulations, allowing corrugated to enter industries in need of prototypes. Because producing prototypes with analog can be expensive and time consuming, digital prototyping is a lucrative business for print providers.
The use of corrugated board in digital print continues to grow as customers demand smaller runs and personalization for popular corrugated applications like packaging, POP displays, and prototypes. Before digital technology can make major strides in the packaging segment, challenges regarding printing to corrugated board like color gamut and image quality must be addressed.
Oct2017, Digital Output