As a technology, LED-UV curing for offset printing is slowly, incrementally gaining favor as a method for curing — using intense UV light of a specific wavelength. It is one of many options, but it can be a game-changing option. It offers instantaneous curing and minimal dot gain. Additionally, it can print on a variety of substrates. Printing and packaging companies must look beyond the novelty of this new technology and find the business case to adopt it.
Two options exist for LED-UV curing adoption. One is to either retrofit an existing offset press or install a new offset presse equipped with the technology. This article presents the views of four LED-UV curing systems manufacturers who offer retrofits for existing presses.
LED-UV cure is right for you?
LED-UV curing technology, which is not only used for sheetfed printing, is now being introduced to web offset printing. | Credit: AMS Spectral Ultra
“If any company is looking to diversify its products to include exotic substrates, films, plastics, or recycled papers, they will need to look at UV printing,” Gary Doman, international sales manager at GEW, points out. Doman says that the first is access to these materials. The second is the speed at which work can be processed in the printing plant. “There is no need to wait for the ink to truly be dry, which enables immediate processing of the materials,” Doman says. Simply put, printed sheets can be immediately sent from the pressroom into finishing or binding.
Asked why companies should adopt LED-UV technology, Bill Bonallo, president and CEO at IST America, says, “The real question is ‘why would you not?’” UV (and LED-UV) technology tends to create opportunities for those using it. Bonallo explains that LED-UV is a more compact option than traditional UV and takes up less space. Also, it is easier to install. As for the business case, he says, “Companies are more likely to gain a competitive edge because they have the technology in place — and remaining competitive is the most important aspect.”
“Once a company goes LED-UV,” according to Jeff Woloshyn, sales director at Eltosch Grafix America, “they never go back.” He says the technology can bring benefits to most commercial or packaging applications and is an enhancement over aqueous-based printing. The biggest thing, he says, is justifying the cost: “UV is more expensive than conventional, and LED is more expensive than UV.” That said, benefits such as instant curing, going straight to finishing, and lower energy costs are major benefits. He suggests that print service providers (PSPs), should consider whether they can pass on the premium to their customers.
Jonathan Fore, commercial lead at AMS Spectral UV — A Baldwin Technology Co., sees commonalities among companies using the technology. According to Fore, they revolve around the equipment being used, the type and availability of the printers, as well as the services they provide. Fore says that UV overall saves time and money while improving the product. He also suggests that companies that print better quality pieces are more likely to use LED-UV. This is because instantaneous cure limits dot loss, which maintains dot matrix and gives a better appearance.
How do you prepare for LED-UV Technology
“You have to understand the technology,” Bonallo says. He adds that regardless of whether traditional UV or LED is used, “the chemistries are ultraviolet-based, so ink rollers, water rollers, and blankets must be UV-compatible — there are different compounds in the rubber.” Further, wash-up solutions and automated wash-up systems must be updated, as will urethane grippers. “This may be easy or hard to do,” he explains. When the press is running, UV requires a tighter control on ink/water balance, “so the press will need to be run tighter and with more control.” He adds that a reasonably competent press operator should be able to move easily into the new technology.
As shown above, LED-UV systems are made up of arrays UV-emitting diodes. These diodes can be used to cure inks at specific wavelengths. | Credit: Eltosch Grafix
Woloshyn agrees, saying the move to UV or LED-UV “should be fairly easy for the operators.” He says press operators enjoy working with the technology and will “fight” to use the UV-equipped press “because it’s simple for them.” He adds that an initial challenge with UV is “getting the inks and chemicals right — all inks and coatings need to cure at the correct wavelength for the technology.”
Fore suggests that PSPs contact their ink suppliers and companies before moving to LED. Fore emphasizes the importance of having all the information. Rollers, blankets, as well as other components, must be addressed. “Once that’s in place,” he says, “you have a fork in the road:” the choice between traditional UV or LED-UV. This can affect the physical adjustments of the press. For instance, traditional presses may require a water-cooled sheet guide to control the intense heat of the curing system — not generally needed with LED. Additionally, UV lamps that produce ozone are toxic and should be vented, rather than LED.
“The good news,” Doman says, “is that most existing presses can be adapted to UV curing.” That said, he starts that sales process by asking potential customers what they want to achieve. Doman says in some cases it might be to eliminate rejected stocks or other finicky stocks. In another case, a customer’s goal may be eliminating spray powders. Doman encourages people interested in the technology’s use to ask questions and learn about the requirements for replacement of press components. Another key preparation step: Talk with your consumables reps. Make sure what you’re getting will be balanced with the technology.
Quantifying the benefits of LED-UV cure
The benefits of LED-UV technology might be obvious, but quantifying them can be difficult. As with any transformative technology key metrics may change. Woloshyn believes that LED-UV’s greatest advantage is its energy savings. He also suggests that you consider whether the energy savings from LED can be offset by higher ink costs.
An array of diodes with a focussed design provides high curing energy and low heat generation. | Credit: IST America
“There are two considerations that come up the most,” Fore notes, “the first of which is increased productivity.” He says it is not uncommon for customers to experience performance that exceeds their ROI assumptions for the technology. “If it can increase the productivity of the press by 25%, then the revenue will follow.” The second is in energy, and in some cases, space savings. On a sheetfed press, he says, companies can move from a gas-fed dryer, “the size of an RV” to a LED-UV curing unit “the size of a computer desk.”
Doman says that, because it is difficult for people to quantify, GEW provides customers with anecdotal data as well as case studies to help understand how and why they may be advantageous. Woloshyn agrees that energy cost is an important metric to consider. Beyond that, advantages can include, “a reduction in reprints because the ink is fully cured — there’s no scuffing or marking.” Another advantage comes in the form of a question: “Are you turning away jobs that you would be able to do with LED-UV?” Last, Doman points to the savings in clean-up time, noting the ink will stay open on the press for weeks at a time, so press cleanings are much less frequent.
Bonallo acknowledges it is difficult to explain the benefits of LED UV technology in statistical terms. Key measures include straight throughput on press, turn time, and increases press up-time. These all translate into productivity. “There are many things to factor in,” he notes, “and there are still a lot of variables.” While he points out that, “99% of companies that go into UV never go back again,” he also says the concept of what LED-UV curing can offer can be “somewhat miraculous.” Despite its advantages, he says, it still cannot deliver the range of cure and application flexibility experienced with traditional lamps.
What’s New and Different?
Doman says current world events — particularly the Ukrainian crisis — will continue to put economic pressure on energy costs, which he says are likely to increase. This may increase the benefits of LED-UV. Doman sees the future as other companies will be able to take advantage of the faster delivery LED UV can offer, as more PSPs have this capability. “When this happens,” he says, “economies of scale will kick in and costs will come down.” As for the current level of acceptance for the technology, he believes, “it has been accepted as a viable part of the process.”
“[LED] diodes themselves and the power supplies that drive them are continuing to develop; that is still ongoing,” Bonallo says. He says that the goal of technology development is to deliver energy to the substrate. Lenses and other similar technology are continually improved to increase, magnify and focus energy to cure. Given this reality, Bonallo adds, the distance between the LED energy source and the substrate is paramount — and is refined in both product development and system installation – making its position within the press a consideration. Advancement continues, he says, and developers are discovering “how little energy is needed to get the job done. It’s a great technology for the right applications.”
Woloshyn, like Bonallo sees increasing power to the substrate in his key areas of research. He believes LED-UV technology, despite the ongoing efforts, is ready to go. “LED can now do all that traditional UV can do — the inks and coatings are there.”
Fore believes that LED-UV curing will gain a larger share of the UV offset area. The tipping point may be in coatings. “The inks are already there. There was once a substantial price difference [between conventional UV and LED]. Now it’s only 5% to 10% different.” LED coatings are behind this curve, he says, and are significantly more expensive than for traditional UV. “When those costs equalize,” he says, “we’ll be there.”