UV LED Easy as ABC
The printing world is continually evolving, and so too are wide-format printing systems relying on UV-curable inks. Among the latest technological developments in a field known for swift technological change is the use of LED lamps to cure prints.
How do these LED systems differ from the hot-light solutions currently used? What efficiencies will they bring to wide-format imaging professionals? And are they all essentially the same, or do the LED solutions differ from one manufacturer to another?
We put those questions to a trio of experts in the field, first among them Eric Custer, the technical manager for Summit UV in Columbia City, IN. Summit UV is a newer company that began as an offset, screen, and flexo house that experienced problems with the heat generated by the lamps used to cure UV inks, Custer says.
About five years ago, Summit UV began experimenting on solutions to the problem, and a couple of years later filed its first patent on its high-intensity UV LED curing system. Today, Summit UV sells to printer manufacturers and users internationally.
At the most recent SGIA show, the company unveiled its Black Diamond, a 5-by-8-foot flatbed inkjet printer using Summit UV’s own curing technology, Custer says.
In general, UV LED printers provide a number of advantages, he adds. Those benefits include the fact these printers do not subject substrates to infrared heat, so much thinner film substrates can be used. They also offer long light life, translating to savings of $1,500 every 500 hours on the replacement of mercury arc lamps.
What’s more, they consume less power, requiring just a standard 110-volt household system rather than the 220-volt power and large power supplies consumed by mercury arc lamps. Finally, some mercury arc lamps create ozone, Custer reports. “That means you have to have better ventilation for the work area, and exhaust some of the heat off the lamps,” he says. “With LED, you have no ozone production, so you don’t need that ventilation. And the atmospheric heat generation is very small.”
Summit UV’s LED technology improves on the process used by others, Custer adds. “Ours is a focused light, whereas the conventional LED systems are flat arrays,” he observes. “The geometry of the way we make our light allows for higher curing speeds per line, due to the high power generation.”
Also, the company’s LED technology is based around the 365-nanometer wavelength, which permits many more formulating options for the ink chemist. That in turn allows for accommodation of a greater range of inks, Custer says.
Andrew Oransky, director of product management for Irvine, CA-based Roland DGA Corp., agrees with Custer about the benefits of using UV LED printers are numerous.
“The lamps consume far less power than traditional UV sources, and as a result are less expensive to run on a daily basis,” Oransky says. “They also run cooler, which allows the use of a wider array of media. Typical UV lamps can get as hot as 1,500 degrees Fahrenheit, and they can warp or distort materials, particularly plastics. In contrast, the LED lamps we are using in the new LEC-300 never reach a temperature of more than 104 degrees, which is roughly the same temperature as warm tap water.”
LED lamps are also an improvement from an environmental standpoint, Oransky says. Not only do they boast lower power consumption and require low maintenance, but their life span is 10 times that of traditional lamps, yielding fewer bulbs in landfills.
The key difference most users will notice in an LED curing printer, he says, is the absence of a shutter mechanism. The mechanism isn’t required because LED lamps can be turned on and off instantly, require no warm up, and don’t have to be left on to prepare for the next curing cycle. This also means that rather than having to wait up to half an hour for the printer to warm up and for you to get the first job out each morning, the printer is up and running as soon as you walk in the door, Oransky says.
“LED lamps emit different wavelengths than traditional lamps, so ink formulation is critical with LED curing,” he adds. “Inks must be designed to cure at the wavelength that the lamps emit. As a result, printer manufacturers need to take a system approach to design and inks. Also, lamps cannot be replaced with generic items.”
The Roland VersaUV LEC-300 Oransky mentions features safe, low-heat LED lamps, and prints CMYK plus white and clear on substrates that include foils, metallic and synthetic papers, BOPP, polyethylene and PET film. It’s “a digital printing device supporting an endless range of highly customized applications,” says Rick Scrimger, vice-president and general manager of Roland DGA Corp. “In addition to short-run production of high-end specialty graphics, the LEC-300 is a uniquely capable prepress tool for label proofs, packaging comps and one-off prototypes.”
Gerber Scientific Products
A different approach to UV LED printing has been advanced by South Windsor, CT-based Gerber Scientific Products, says director of inkjet printing Curt Brey.
“Gerber’s approach is different in both the ink and the light source,” he explains, noting that in the UV curing field, the two approaches used are as different as night and day, black and white and particularly hot and cool. One side features the mercury-vapor lamps, with a contact temperature on the surface of the substrate of 300 to 400 degrees Fahrenheit, and a temperature on the lamp of from 400 to 600 degrees Fahrenheit.
At the other end of the spectrum are LED curing technologies, which Brey says are typically found on higher-end printers of $200,000 or more.
“Gerber has secured the intellectual property to take hold of the space in between those two curing technologies, with high-pressure mercury vapor lamps on one side and LED on the other,” Brey says. “Our technology can only cure our inks. It is neither hot nor inhibited in its life. The high-pressure mercury vapor lamps have a useful life of 500 hours, while ours last thousands of hours.
“We’re the only company we know of today that covers our lamps under the one-year warranty and the service contract. Our lamps simply don’t break down as fast as high-pressure UV lamps. They’re an entirely different type of technology.”
Solara ion lamps from Gerber Scientific generate maximum surface temperature of just 85 degrees, which is the reason the system is termed Cold Fire Cure. At these cooler temperatures, the printer can imprint a wide variety of materials, including heat sensitive materials like paper and biodegradable and recycled signboards, Brey says.
The other attribute of the printer is that it successfully prints with cationic inks. The GerberCat cationic UV ink is specifically formulated to work with the Solara ion. Its features and benefits include adherence to more materials than any other inkjet ink, great resistance to abrasion with unmatched scratch resistance and the largest UV color gamut in the industry, Brey says.
In addition, it is a highly flexible ink that supports vehicle wraps and vehicle graphics applications, offers the greatest chemical resistance of any ink marketed, and is environmentally friendly in that it enables the Solara ion to generate minimal waste.
“GerberCat cationic UV inks have proven to be everything we’d hoped them to be and more. And the Cold Fire technology is offering graphics printing shops more solutions and more applications than we’ve seen from any printing solution to date.”
Jeff Steele is a freelance writer who specializes in the field of business management, marketing, and protocol, especially as they apply to wide-format printing firms. Contact him at email@example.com.
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