In a New Light: UV-LED Curing Powers Sheetfed Offset Printing

And just like that, it’s dry. In mere milliseconds, UV ink, when exposed to intense UV light, transforms from a liquid to a solid state. With this reality comes opportunity for those using sheetfed offset presses. In the past few years, UV curing has been refined, using LED light sources that generate much less heat than traditional mercury-based lamps, while at the same time using substantially less energy and possessing a much longer functional life (20,000 hours versus 3,000 hours). For some sheetfed offset printers, the move to UV-LED curing draws its motivation from a drive to access new markets and use new materials. For others, the attraction is quicker turnarond times.

This article will explore UV-LED technology from the perspective of press manufacturers; UV-LED retrofit suppliers, whose systems can convert conventional offset presses over to the new curing technology; and the users of UV-LED sheetfed offset presses, who will discuss their experience adopting UV-LED, and the benefits they have experienced from doing so.

For New Presses, a New Approach

Speaking on behalf of Komori America, Doug Schardt, the company’s director of product management, says interest in UV-LED is definitely increasing. What may surprise some is that UV-LED, according to Schardt, “is the opposite of specialty; it is more for mainstream printing.”

He views the technology as an alternative among available choices, but not a broad replacement of either traditional UV curing systems or evaporative drying. Schardt says he gets a lot of questions about UV-LED systems, and believes the technology, “has enough traction in the market that it’s now moving forward.”

Clarence Penge, executive VP for Heidelberg North America, says his company started testing UV-LED systems in 2008, and did not then see it as a strong opportunity, due to limited chip supply and slow curing speeds. Reconsideration of the technology took place in 2012, and showed that the technology had clearly improved.

Penge states that while Heidelberg offers both traditional and UV-LED systems, there has been a strong drive for UV-LED, particularly in Japan, where the government offers subsidies for the purchase of lower-energy products. Demonstrating the progress of the technology, Penge shared that by 2015, Heidelberg had more than 100 LED-equipped printing units installed in Japan.

LED curing for offset printing didn’t exist until its 2008 drupa premiere by Ryobi, reports Chris Manley, president of Graphco, which distributes RMGT presses in the U.S. The initial placements of the technology, he says, were in energy savings, driven by the price of energy in Japan, where electricity costs are three times what they are in the U.S. The move to LED removed the heat of traditional UV curing, and offered energy savings, faster makeready, and improved speed-to-market — all on an affordable press that could “help with huge improvements in quality and throughput,” Manley notes.

Further, UV-LED allowed some smaller printers to “punch above their weight class” in production and become more competitive. He adds that almost all commercial printers who bought into UV-LED curing have not gone back.

Chris Travis, director of technology at Koenig & Bauer, says his company started investigating UV-LED eight years ago. Adding that Koenig & Bauer is the only offset press manufacturer to also produce drying systems, the company did extensive testing with a wide variety of inks to determine appropriate printability and curing.

Travis stresses the importance of ink, stating that when customers consider UV-LED, their first question often is, “are there inks?” He says UV-LED is 100% ready, with inks and coatings. The technology is not the right solution for every company — it all comes down to the technology meeting the needs of the printer, and the press configuration it requires, according to Travis.

The Advantages of UV-LED Technology

The purple glow of this Eltosch Graphix UV-LED curing system, shown above, differs greatly from the blinding light of traditional UV curing.

The primary advantage of UV-LED systems, according to Schardt, is instant curing of the ink. Because of this, he says, users experience none of the challenges associated with traditional drying via evaporation and heat. This means no marking of the printed surface, no spray powders, and no wait time between printing and finishing. He describes the systems as being “highly efficient.” To these advantages, Schardt also adds the “instant-on/instant-off” nature of the LED light sources, and the fact that there is little heat going to the substrate.

As advantages, Penge highlights lower power use, lower heat, and the ability — on Heidelberg presses —to scale the width of the light source to match sheet width. He highlights increased speed to market as a strong benefit of the technology, and is seeing the most UV-LED growth in the commercial printing segment, followed by labels. Use in packaging, he says, is “still limited.”

As a press manufacturer, Manley says RMGT was able to gain a high level of experience in serving the needs of UV-LED users, and now has roughly 2,000 UV-LED-equipped presses placed worldwide. For those seeking to adopt the technology, he advises that it is important to purchase a machine engineered for UV-LED, as they are designed to address specific challenges, such as the effective venting and filtration of ink mist.

Manley also urges print providers to consider, or at least understand, two-step curing, during which the process color is cured first, followed by coatings. Doing so, he says, can result in up to a 15% improvement of glossiness.

With so many advantages to using UV-LED, what is holding it back from being the primary curing system moving forwards? Schardt notes the technology has some drawbacks. Traditional UV curing systems, he says, provide light across a wide spectrum, offering choices for a variety of inks and coatings. UV-LED, however, operates at very specific wavelengths, meaning curing and ink must be “locked in” in order to successfully cure.

From the Heidelberg perspective, Penge says that the move to UV-LED may require tweaks to solvents, rollers, blankets, and fountain solutions in order to be maximized. “Once the learning curve has been tackled,” he adds, “you would have to search high and low to find a printer who wanted to go back to conventional ink printing — it just doesn’t happen.”

Regarding implementation of UV-LED, Schardt describes the learning curve as being slightly different, and notes some “un-teaching” may be required for those used to traditional UV. Washups, he says, may also be different.

According to Manley, there are four key selling propositions for a UV-LED sheetfed press: increased speed to market, which allows printers to say “yes” to more jobs; improved print quality, consistency, and color; a strong opportunity for print enhancements, including high gloss and chemical embossing (using a reticulating varnish); and its placement as a lower-cost alternative to traditional printing. Those customers who have grown into plastic substrates, he says, have experienced a strong opportunity.

One early-adopting customer, Travis points out, was able to print a product at speed, at highest quality, with no need for coating. For that company, he says, that has been the biggest benefit of UV-LED. He adds one customer recently bought a press without a coating unit — a testament to that firm’s belief that production step was no longer needed.

For Existing Presses, a Retrofit

Quality printing and the ability to achieve an immediate cure for the next process are two benefits of UV-LED technology.

According to Bill Bonallo, president and CEO of IST America, the universal advantage of UV — whether with traditional or LED systems­ — is an increase in overall productivity and expanded application possibilities. He states that printers are no longer held captive by the drying process, and notes that on multiple-pass jobs, the sheet can go right back through the press; if not multi-pass, it can go straight into finishing. UV-LED curing in the commercial printing sector is “no longer a niche — now it is ubiquitous.”

Bonallo points out that 75% to 80% of sheetfed offset presses sold today have UV capabilities built-in, a change driven by higher productivity and better market opportunities.

Gary Doman, international sales manager for GEW Inc., says that in the U.S., U.K., and Europe, the motivation for printers toward UV-LED has been to diversify their products. He has witnessed an increased use of the technology for plastics, and even some food packaging.

“Retrofits go pretty easily these days,” Jeffrey Woloshyn, sales director of Eltosch Grafix, notes. He says a prime motivation for retrofits is the move from aqueous inks to UV-LED curables, and that a retrofit is the most economical way of doing so. When most companies undertake a retrofit, they are doing so on their primary presses.

The ease with which a press can undergo a retrofit to UV-LED, Bonallo reports, is dependent on several factors. He says that exposure to strong UV light sources can affect press-related rubber, including rollers and blankets, so some presses would need to be adapted. If the press is “factory UV prepared,” he says, “then [UV-LED] can be added with minimal impact.”

One of the key factors in the success of a retrofit, Bonallo adds, is the openness and experience of the technology provider. He says IST will, for instance, communicate with the Heidelberg factory to make sure a project goes smoothly by following factory requirements for their retrofits.

Woloshyn describes the learning curve as “very short,” and adds that training in the use of a retrofit system is quite easy. He says that, in his experience, once companies put UV-LED on the press, they never want to revert back.

While Doman describes the process to retrofit a press as “relatively painless,” he also adds that a learning curve exists. The inks and chemistries are different, as is working with new materials. He adds that printers new to UV-LED often approach him with questions relating to
ink adhesion.

Retrofit Success Strategies

Asked about the major benefits of UV-LED, Woloshyn highlights lower energy use (this is particularly profound among companies shifting to LED from traditional UV systems), and rapid turnaround times. Doman speaks of the advantages of immediate cure, how short runs can be done “like on a digital press,” and the elimination of time required before finishing can commence. Further, Doman says, “what you see on the press is what the print will look like,” given that the ink is fully cured.

IST America’s Bonallo notes UV-LED can bring great flexibility to printing applications, adding, “there is literally nothing you can’t print on. He says this, however, with a caveat: “What are your customers looking for? If it’s a miracle, then that’s going to take a great deal of planning.” Further, careful listening, and matching the technology to customer needs, will provide the best path for success.

Doman says that those adopting UV-LED should, right off the bat, expect a sharper, brighter looking print, and the ability for the print to be handled right off the press. To acquire the retrofit system that best suits their needs, he says, printers should be able to define exactly what they need to achieve (e.g., printing on plastics), and any challenges they are looking to overcome.

For those companies seeking a press retrofit, Bonallo points out that, despite the new technology, successful printing — UV or otherwise — still involves a careful balance of chemistries, and doing things right. “If things are set up correctly,” he says, “you have endless possibilities.” Even so, he notes skill, training, and careful planning are needed ingredients for success. Time-wise, the physical retrofit process can take at least a week, Bonallo adds, or more depending on needed press modifications.

In approaching the decision to add an UV-LED retrofit, Woloshyn urges companies to talk to their customers — many printers, he says, have customers who would prefer UV ­— they just don’t know it.

Asked whether UV-LED will become the “new normal” for sheetfed applications, Bonallo says that while he loves UV curing, for ultimate success, the proper UV technology must be matched to the right set of applications.

Woloshyn believes UV-LED will take over from traditional UV, but will continue to exist alongside both infrared and warm
air curing.

Doman expects that, in five years’ time, UV-LED will be included in most new presses. “You’re going to have to have it,” he says, noting “legislation will drive that as well, due to a need to reduce VOCs, and for environmental sustainability.”

First-Hand UV-LED User Experiences

How well do UV-LED equipped presses work in helping printing companies maximize production, and what has the experience been regarding implementation of these systems?

According to Kevin Heslin, president of Seaway Printing in Green Bay, Wisconsin, the technology was included on the company’s Heidelberg Speedmaster XL106 perfecting press. Seaway, Heslin says, was looking for better turn times, resulting from the immediate curing of the ink. He describes the ability for printed output to go straight into bindery as a “great experience.”

Aaron Greebel, VP of AJ Images in Roselle, New Jersey, says his company began exploring UV-LED as a way to reduce sheet size on its manroland 708 P-LV perfector. He says adding the system has resulted in “improvement overall through the shop,” and that the elimination of wait times has been beneficial.

Jordan Hagg, president of Hagg Press in Elgin, Illinois, was made aware of UV-LED technology by Graphco. He says that since adding the technology, Hagg Press has experienced great success with it. Hagg says the biggest impact has been the elimination for drying time. He echoes others by saying his print shop can move print directly into the next process step, such as finishing. This has enabled the shortening of production times overall.

Although Greebel did not adopt UV-LED as a way to gain entry into a new market or product areas, the technology has helped AJ Images better satisfy its customers. For his company, which he describes as “a medium-sized family business with an emphasis on high-quality output,” having navigated the learning curve of UV-LED has allowed the shop to provide the high quality its customers expect. Greebel adds that, as a technology, UV itself "doesn’t help or hurt. UV is different.”

Hagg says that the motivation to adopt UV-LED was not about access to new markets, or the ability to print on a wider variety of substrates. “That is by choice,” he says, “as we aim to capitalize on this technology to further reinforce our current strengths in the market.”

For Heslin, UV-LED is, simply put, a different way of curing the ink. As a result of the technology, Seaway Printing has experienced improved turn times. “With conventional printing, we would wait two to four hours before going into bindery.” Now, he says, the work goes straight in, noting it allows more production flexibility and takes a level of complication out of the process.

Press operators at Hagg Press, Hagg reports, shared with him that they experienced a small learning curve, but experienced a much easier transition than was originally expected.

Approaches to Adoption

Jordan and Taylor Hagg, of Hagg Press, stand in front of their RMGT UV-LED sheetfed offset printing press.

The benefits for Hagg’s commercial printing busines, are numerous. He, like others, highlights immediate drying with no waiting, the elimination of spray powders, lower energy use, and improved print quality, “because the ink is cured before it can be absorbed into the paper.” Further, Hagg says his company can now do UV coating inline — something they couldn’t do before.

Greebel notes AJ Images’ ink management software is showing less usage, which may be attributable to the ink system, where, by weight, all UV ink is cured, while a significant volume of traditional inks are evaporated away. Greebel adds that because UV inks don’t dry in the air, there is no need for nightly press washups. Instead, washups are done every three days, allowing additional time for production. In additional to ink savings, Heslin highlights that UV improves print quality on uncoated stock, which is due to the ink sitting on top of the substrate, as opposed to being absorbed into it. As a result, he notes that customers are pleased with the outcome.

Pictured is the GEW modular lamp array in operation at Elgin, Illinois-based Hagg Press.

Asked about considerations to be taken before a company moves into UV-LED, Hagg advises fellow printers to be aware of the high up-front costs of the systems, and the high costs of both UV ink and UV coatings. That said, Hagg notes the move to UV-LED “is still worth it, and we would do it all over again if we had the chance.” Greebel, summing up his company’s move into UV-LED curing, says, “It was the right thing to have done, and we would do it again.”

Based on the input from this article’s roster of users and purveyors of UV-LED systems, the technology is a fully-realized and viable option for sheetfed offset printing operations seeking to maximize productivity and shorten delivery times. It is a proven technology that serves as a strong choice for either a new press, or as a retrofit to an existing one.

Like many new technologies, there exists a strong “wait and see” approach within the adoption curve. It seems, however, that the adoption of UV-LED curing technology is a matter of “when,” not “if;” and a matter “how,” not “why.”