By Melissa Donovan
Aluminum cans are commonly used in the beverage industry, whether for beer or soft drinks, and anything in between. With craft breweries, small businesses, and the like popping up to rival big brands, it’s no surprise that direct to object (DTO) digital printing is a preferred method to print labels on these cans.
Shorter runs, limited editions—both present opportunity for digital printing to excel in this space. Brands look to achieve highly decorative graphics with standout colors and messaging. The technologies available, specifically UV printers, offer fast curing, no outgassing, and excellent ink adhesion. In most instances post-treatment processes aren’t required, further accelerating usage.
“Think limited editions, seamless wraps, variable text or names, texture prints that you can feel, gloss or matte finish—these are all viable applications or effects when using a UV rotary printer, for example, to decorate cans. The possibilites are endless,” notes Michael Perrelli, sales director, Innovative Digital Systems.
Out with the Old, In with the New
Traditional methods of labeling aluminum cans present increased setup times in addition to limited design flexibility. DTO digital printing shortens production time in many stages of the process while presenting endless design possibilities.
Mike Pecorini, sales manager – Midwest, West, South, Koenig & Bauer Kammann US, lists traditional methods of labeling as lithography, shrink sleeving, pressure-sensitive labels, and screen printing.
For long runs, “traditional decorators are offset printers, which apply spot colors at multiple stations at speeds of up to 2,200 cans per minute. They shine with limited changeovers and high volumes, thus minimizing cost,” explains James Bullington, CTO, LSINC Corporation.
“The traditional decoration process involves large production machines that form the actual can and an offset CMYK printing plate press to get the artwork on the cans. While this process is fast, it requires a significant amount of space, equipment, and money to operate and maintain,” admits Philip Chu, product manager, Roland DGA Corporation.
Moving away from higher volumes, pressure-sensitive or self-adhesive labels applied to aluminum cans are ideal for shorter runs. “The print quality and color graphics can be very good, and you can apply features to labels such as metallic look, gloss, and matte to be able to customize the label. However, there are some disadvantages. The label can only be applied to some part of the can and does not produce a full coverage effect,” shares Paul Edwards, VP of the digital division, INX International Ink Co.
“A more recent trend is to utilize shrink sleeve label technology to apply the decoration. This has the benefit of applying full coverage where the can is not flat but is fully wrapped around, which gives it a higher quality look more akin to a standard decorated can. As with the self-adhesive label, good print quality can be achieved and features added in terms of the look,” continues Edwards.
Shrink sleeving also addresses the demand of shorter print volumes, but “with bans and restrictions issued in Canada and the EU on disposable plastics, such as shrink sleeves, an opportunity opened up for DTO digital printing,” shares Bullington.
DTO digital printing eliminates consumables like plates and screens, the production line footprints are smaller, and it is an economical process. “DTO digital printing offers high-resolution, full-color printing directly on cans without the need for plates or screens. It allows for quick design changes, customization, and reduced waste, making it ideal for both large and small production runs. This results in fast, more flexible, and sustainable production,” states Pecorini.
With DTO digital printing, users “can print a custom design with rich, bold colors and add unique textural and dimensional effects. The end result is an eye-catching product that can’t be done using the traditional/factory process,” admits Chu.
“Clearly, there are multiple digital label presses available today that can create short-run labels with a high level of personalization. However, you must consider the complexity of post print and the process for applying the labels after they have been printed onto rolls. DTO can effectively print all cans with some form of variation if required,” says Edwards.
Another benefit of DTO printing is in the form of sustainability. “Given the strong recyclability credentials of aluminum cans, this is likely to become a strong selling point as both consumers and regulators look for packaging to become more sustainable. With supply chain sustainability also becoming more intensely scrutinized, lean in-house packaging production options may now also be more appealing for small- and medium-size manufacturers,” shares Gabriel Vallellanes, technical project manager, Inkcups.
Highest Usage
Beverage and craft brewers, reusable bottle manufacturers, personal care, and specialty food products all currently utilize DTO digital printing for aluminum cans.
According to Pecorini, beverage and craft brewing industries are the biggest adopters so far. “These sectors prioritize unique and eye-catching designs to stand out in a crowded market. DTO’s ability to offer high-quality customizable prints with quick turnaround times is a perfect match for the frequent product launches and limited edition runs commonly found in industries such as these.”
“The craft brewing industry today is taking full advantage of the ability to highly decorate cans to market their unique products. The ability to produce very short runs with high quality, fully round can graphics, with relatively short lead times and at a reasonable price point, is very compelling. The vast number of small brewers in the U.S. is really driving strong growth in its adoption,” shares Edwards.
Vallellanes agrees about craft brewers influence on accelerated adoption. “Small to medium volume cylindrical inkjet printers can print up to 600 units per hour depending on image size and can be a great opportunity for craft breweries and other independent beverage producers who are hoping to vary run lengths and utilize a wide array of artwork.”
Other beverage companies leveraging digital print for its short runs and variability are soft drinks, either high volume or even more localized or specialized. DTO digital printing provides what Edwards says are “on-the-shelf marketing options.”
Another segment benefiting from digital pricing is reusable or resealable aluminum bottles. “Resealable aluminum water bottles customized for resorts and events are generated in low enough quantities that minimum orders with traditional decorators are not met. DTO fills the gap well,” continues Bullington.
Along the same lines, Perrelli notes that customers of Innovative Digital Systems print cans for resorts, experiences, and corporate events. “This is no different than what we are seeing on the cosmetic packaging side, many folks prefer the higher end look of direct printing to the can when compared to wrapping it with a label.”
Going forward, DTO digital printing may expand into other sectors such as personal care and specialty food products. This is because “brands in these areas increasingly seek to differentiate themselves from the competition with more personalized and premium packaging,” explains Pecorini.
However, it is “the beverage industry that is likely to remain the primary driver due to its high demand for both aesthetics and flexibility in packaging,” admits Pecorini.
Over time Edwards believes there will be greater adoption into longer run products, where a modification of the design of an otherwise very long run will become possible and extend the ability of a brand to market their products. “I believe more people will see the benefit of the DTO process on cans. It will lead to greater overall adoption—and specifically adoption of longer run products—when the technology and cost efficiencies make sense,” notes Edwards.
Ink Sets
Digital print employs different ink sets depending on the device and printheads. Printing directly to aluminum cans presents challenges that only certain ink sets can meet.
UV-curable inks are preferred for multiple reasons. “These inks are known for their excellent adhesion, durability, and resistance to environmental factors such as moisture and light,” explains Pecorini.
The curing process for UV ink is advantageous to the overall process. “As these are photosensitive inks that are cured via UV light, they don’t have to outgas like eco-solvent inks, or use heat to cure—just UV light,” notes Chu.
Fully cured immediately after printing, UV-curable inks “eliminate the need for any heated post-curing processes. This makes them ready for immediate progression to the filling part of the process,” says Pecorini.
UV ink also allows for unique effects, for example simulated embossing or eye-catching textures. “This UV printing process produces a premium product with vibrant graphics and stunning tactile appeal that cannot be easily matched,” adds Chu.
“Currently, energy curable technology is employed for DTO printing systems. The technology may include different curing methods, from UV mercury lamps to LED and ebeam. However, most of the focus is on LED cured systems for a variety of technical reasons,” explains Edwards.
Water-based inks are “unsuitable for aluminum can applications,” according Pecorini. “These inks suffer from poor adhesion to metal surfaces and lack the necessary durability, particularly under the demanding conditions that cans face during storage, transportation, and handling.”
In all scenarios, “the chosen ink set must be designed for use in the printer in question and not just for the printhead type used in the printing system; this is critical for both reliability and final can function. The inks need to be designed to function on the can types in question,” says Edwards.
“Cans get used, they get placed in corrugated packages, or they go into can carriers or toppers in four or six packs. Meaning that they get handled, move into another process step, or they potentially clang against each other and you need an ink that can stand up to that,” adds Perrelli.
Pre and Post Considerations
To ensure ink adheres properly to the can during the printing process, pretreatment should be considered.
Cans may have certain treatments on them from their manufacturing process. A pretreatment may be required if the ink is not compatible with the necking oils used by the can manufacturer, explains Bullington. This is critical to ensure proper ink adhesion.
Pecorini believes pretreatment of the aluminum can is necessary for optimal digital printing. “Anti-static devices and a flame treatment, both integrated in machines like those from Koenig & Bauer, are used to clean and prepare the surface. This ensures the ink adheres properly and results in a high-quality, durable print.”
“A standard can or one with a base coat can be enhanced by the application of a clear pretreat before decorating. Inkjet is a non-contact technology and the spread of the ink on the can is important to its print quality. Also, the way in which the pretreatment interacts with the inks to enhance adhesion has benefits in some later processes, such as pasteurization,” says Edwards.
Depending on the ink technology used, post treatment may not be required, according to Pecorini. For example, UV-curable inks are fully cured when the can comes off of a Koenig & Bauer machine. This eliminates the need for additional curing steps and ensures the can is ready for immediate use.
Post treatment can be dictated by the user and their usage needs, thus rendering it optional. “When printing with UV devices and ink, I like to use a post cure—basically running the laps across your printed surface to make sure the ink has had enough time to cure on the substrate. This helps with durability. By adding gloss you can cover your entire printed piece with a protectant layer that’s similar to that of an applied laminate,” suggests Chu.
“Post treatment can provide different visual quality effects than what are seen on the ink alone, as well as offer benefits in terms of post processing, such as with durability. Although not strictly necessary, it is beneficial to the final product,” says Edwards.
“While digital print has long been known for high image quality, continuity of tone, wide color gamut, and precise text, DTO inkjet printing facilitates the creation of tactile effects with spot varnish or by varying ink opacity. As an example, tone-on-tone varnishing can be used to highlight a can’s sheen to create a ‘wet’ look. The only limit is the imagination of the designer,” attests Vallellanes.
Special Requirements
The surface and shape of an aluminum can presents other considerations in terms of printing.
The quality of the product is paramount and something to observe prior to the print process. Avoid cans with dents or other defects, advises Chu. “It’s important for the printing surface be as smooth and even as possible. The last thing you want to happen is to have something pop up and cause a printhead strike/crash.”
Pecorini recommends cans are in a basic formed shape—pre-necked and flanged—for easier loading on whichever printer.
Prior to printing, ensure the can has undergone proper surface preparation. “Clean the surface of the can with 91 percent isopropyl or denatured alcohol and then let it air dry. This will help ensure that the surface is as clean as possible before printing and further improve the graphic results,” suggests Chu.
What the can experiences post print—out in the world—should be considered. “Inks and coatings applied to an aluminum beverage can must have resistance to abrasion during transportation, good adhesion before and after pasteurization, and acceptable resistance to fading under store light,” advises Alex Folloso, VP of R&D metal decorating technology, INX.
Bullington warns that ink printed too thick will flake when the can is crushed or dinged.
Other advantages to look into include software—maybe bundled with the digital printer—that optimizes ink application around the curved neck and bottom of the can. This enables full-height printing with both precision and consistency, explains Pecorini.
End to end, the print process benefits from automation, whether this is executed via software or some type of material handling. For example, Innovative Digital Systems offers a robotic loading system included on its various printers in addition to the ability to stack multiple cans in a single tool. “We have a full UV rotary printer line up that ranges from one- and two-up machines to a 2×2 shuttle system. All of them are capable of producing full color, seamless wraps, and various print effects on aluminum cans. With a printer for every need, speed, and budget, the Innovative Digital Systems line of UV rotary printers can meet the can printing needs of many companies,” says Perrelli.
Aluminum Cans
Between large brands considering shorter runs that promote limited edition beverages to smaller companies looking for minimal investment when it comes to branding and messaging, digital printing is poised to present opportunities. Highly decorative graphics with standout colors, and even specialty finishes like varnish, are sought out to differentiate products from the rest of the pack.
“As average run lengths for packaging come down and brands and retailers seek increasingly creative ways to achieve standing out on the shelf, DTO digital print is set to democratize packaging for small and medium beverage manufacturers,” notes Vallellanes.
DTO digital printers are designed to print to more than aluminum, but aluminum cans and bottles are prevalent items.
Nov2024, Digital Output
