21 August 2016 Analogue Printing Technologies

LED continues spread across applications

Fogra's forthcoming conference will cement the key role that LED plays in UV curing – with the clock ticking on classic UV technology.

Traditional UV will be finished within four years according to Steve Metcalf, president of Air Motion Systems.

He is due to speak at the up coming UV Printing Users Forum organised by Fogra in Munich. The US company produces both traditional UV and LED UV where it has been committed to innovation since 2008. Currently 95% of its R&D budget is targeted at LED technologies.

At the recent Drupa it introduced Multiwave LED which blends multiple UV response points within a single system to match the broad spectrum of traditional mercury vapour lamps that have been used in printing since the mid 1970s.

That classic UV era is coming to a close, says Metcalf. “We predict the end of mercury arc lamps by the next Drupa. LED curing is more efficient, cost-effective, environmentally friendly and practical that traditional UV curing. Printers won’t be able to avoid turning to LED if they want to stay relevant and profitable.”

This is underlined by the expansion of LED technologies into new ares of printing. There is an AMS system on a Goss M600 16pp heatset web press in Japan replacing the conventional oven and IST-Metz is trialling LED UV on a Swiss newspaper.

Here the LED arrays are replacing an existing UV lamp system on a Wifag OF-7. The LEDs and the Huber ink that is matched to their energy profile are able to operate comfortably at a 200m/min press running speed with just a single array per side of the web rather than three MV tubes each side.

During the trial LED was used on one side of the web leaving the classic set up on the reverse in order to provide a real life comparison of the technologies. The press was cranked up to reach its maximum of 32,000cph, equivalent to 500m/min running both a 45gsm sheet and a 70gsm matt coated which would offer greater resistance to ink absorption.

The results showed good results at all speeds on the newsprint and a fall off in quality on the coated paper at the highest press speeds compared to the conventional systems. This is the result of higher ink weights where energy is absorbed by the black ink resulting in a lesser cure for process colours.

However, IST is optimistic, declaring that with LED UV inks “high production rates can now be achieved. Surface speeds such as those usually achieved on presses for narrow-web label printing or in sheetfed offset printing, were exceeded by a significant margin in the test runs on the newspaper press.”

The Multiwave approach taken by AMS and similar developments by Baldwin may be effective at tackling this issue. Stefan Feil, IST-Metz’s technical marketing director, will be one of the presenters at the Fogra event on 19-20 October.

It will update participants on these developments as well as those announced at Drupa. There will also be sessions on progress in developing low migration inks for inkjet printing and in tackling the tendency that coatings and varnishes have had to yellow under LED wavelengths.

The answer appears to lie in using the diodes that emit UV energies at different parts of the spectrum and different types of UV to ensure both deep and surface cure for the technology.

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Swiss trials

Swiss trials

IST-Metz has tested the viability of LED UV for newspaper printing in Switzerland using a new ink developed by Huber group sensitive to the LED UV wavelength.

The success of the tests point to increased opportunities for the UV technology, something that AMS president Steve Metcalf says will mean a complete transformation within the next four years.

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