Wide-format Graphics: The advantages of UV-LED Curing

The wide-format printing sector is familiar by now with ultraviolet (UV) curing, which has allowed compatible inks to be instantly polymerized during the printing process, rather than rely on more traditional solvent-based inks, which must be allowed to dry and off-gas after printing. More recently, however, another game-changer for specialty graphic applications has been the use of light-emitting diodes (LEDs) for UV curing, instead of arc lamps.

“UV LED lamps provide unique capabilities we could not have delivered to our customers with traditional mercury-based lamps.”
Ken Hanulec, Vice-president of marketing for inkjet systems, EFI

LEDs open new possibilities for UV curing, including the printing of thinner and heat-sensitive materials, as LEDs run cooler than arc lamps. They can also be integrated into slimmer, more compact machines, will last longer with less need for maintenance and will save electrical costs through their greater energy efficiency. Further, LEDs contain no hazardous mercury or ozone and they emit UV light within a safer wavelength range than arc lamps do.

For LEDs to compete with arc lamps in the wide-format printing sector, of course, they have had to progress to the point where they can cure inks just as effectively, with a reliable breadth of UV light. The irradiance output of LEDs has certainly increased significantly over time, but more relevant to UV curing have been the design innovations in LED arrays, optics and thermal management that have enabled an increase in total UV output.

It has helped that wide-format printer manufacturers have worked closely with ink formulators to optimize UV LED curing. No longer merely an ‘emerging’ technology, there have been multiple successful deployments over the years, with a myriad of benefits.

Indeed, there is widespread adoption today of UV LEDs compared to just a few years ago, with ink formulators, printer manufacturers and print service providers (PSPs) working together to advance the technology.

Advances in UV-curable ink formulations have also helped make UV LEDs a viable alternative to medium-pressure mercury lamps.

“UV LED lamps provide unique capabilities we could not have delivered to our customers with traditional mercury-based lamps,” said Ken Hanulec, EFI’s vice-president (VP) of marketing for inkjet systems.

Energy assessments carried out by Fogra, a graphic technology research association, have found EFI’s Vutek printers with UV LEDs reduce energy use by up to 82 per cent when compared to printers using conventional mercury arc lamps. Even in print-ready mode, for example, the LEDs save up to 77 per cent in electricity use because they are turned off when the machine is idle between jobs, where mercury arc lamps would continue to consume power.