04 September 2018 Analogue Printing Technologies

LED UV: A clearer picture emerges

Behind the hype of LED UV is either an industry changing technology or a dead end, destined to have only limited applications. As the hype settles, it is possible to understand the benefits and limitations of the technology.

There are plenty who will declare that LED UV is the future of litho printing, the first deep change since automatic plate changing which has since led to ever greater levels of automation. There are others who think of it as a fad, or something that belongs in a very limited niche.

However, sales of presses equipped with LED UV or perhaps H-UV or similar single mercury vapour lamp technologies, suggest otherwise. While there are relatively few B1 format presses with this new generation of UV, there have been plenty of installations in the B2 or half sheet size. And in the revived SRA1 sector, LED UV is almost mandatory.

The advantages of low energy UV have been well explored: instantly dry sheets for immediate finishing, printing on unfavourable substrates, reduced energy consumption compared to IR dryers, no requirement for a seal, so fewer printing units needed with the cost and space saving that this entails. Likewise the downsides are equally well known: high cost of ink, aggressive environment for plates, eye waveringly expensive varnishes which have a tendency to yellow and high initial cost for the LEDs.

This can mean that payback will take ten or more years according to Matt Rockley at Heidelberg. And this is unfair to sell to a print company that does not fully understand that the extra costs will continue perhaps becoming burdensome. “We want repeat business,” he says. Heidelberg has all the tools in its arsenal, conventional, LE-UV using a single doped UV lamp and LED, and now with a more affordable Compact LED unit. This puts it in position to deliver impartial advice, says Rockley, consulting with customers about their markets and real rather than perceived needs.

When new generation UV first arrived, Heidelberg UK produced a White Paper on the pros and cons of the technology, pointing out that the cost of inks and the initial set up would limit its application and hobble the competitiveness of users compared to those running standard litho presses. Those arguments still hold says Rockley. “LED suits companies with a strong environmental ethos, or who have no requirement for coatings or who perhaps have two or three standard machines and want a machine that can be dedicated to printing uncoated papers. We can colour match across the technologies so mixed production is possible,” he says.

As well as the well advertised benefits of printing on uncoated papers, UV is ideal for those printing a lot of lightweight work, for printers running papers from 60-80gsm he says. “But if you are running some silk papers, you may still need to seal the sheet which cancels out some of the arguments.”

Heidelberg’s prospect sheet in this country shows a big divide between the UV technologies, nine out of ten opting for the mercury vapour option in the UK. There are differences in different parts of the world. Japan for example is rapidly becoming an LED UV only market. However, the single lamp LE-UV is more of a known quantity thanks to the success that Komori has enjoyed with H-UV presses and it is a lower cost option. The lamps, while considered a consumable, are far less expensive than an LED array. And there is probably a greater availability of suitable inks and varnishes.

Both technologies are associated with energy savings on press, though exactly how much is saved is open to debate and relates to variables like ink coverage, paper and dryer settings. J Thomson Colour reckons to have saved 80% of drying costs on a six-colour KBA Rapida XL106 with LED compared to the conventional press it has replaced. There is also a waste saving, but again how much of this is down to the technology rather than to operating a press with the latest technology is open to debate and it’s fair to say that the press replaced did not have the most up to date dryer.

“They are printing some difficult stocks,” says Craig Bretherton, Koenig & Bauer’s product marketing manager for the UK. “There is no longer a need for a tactile layer of spray powder to prevent blocking of the stack, nor any need to have stacks split into small piles across the press hall. They will print anything on any material as if it were a normal job.”

The configuration provides the option of additional coatings for value added effects not possible on a conventional press, or to add a lick of seal to protect a silk stock. Bretherton explains that coatings on these papers can have a tendency to flake taking the ink with it and transferring to folders or binders. A seal prevents this. “Jobs that used to take a week to print and often needed to be put back on press can now be printed in a couple of hours and be out of the factory,” he says.

Given these advantages it is no surprise that the press supplier has a number of LED UV projects on the go. And Bretherton adds when there are demonstrations it is LED that is the attraction. KBA works with Toyo on the ink side and while the consumable remains expensive, he reckons that given the speed with which the market is growing, suppliers are becoming ‘amenable’.

But this is still a barrier he acknowledges. “If we are talking to the finance director the questions will be about the financial costs; if we are talking to the production manager it is about the way that the technology solves the production issues. The companies that have adopted LED UV do not see the ink cost as an issue.”

That said, like Rockley at Heidelberg, a solution might be a combined press hall: one press with LED UV for difficult substrates and shortest runs, another with conventional set up for longer run and less time pressured work. Which is how J Thomson Colour operates.

Komori has been the market leader in this sector with H-UV as a package of press, UV technology, blankets, inks and everything else needed to ensure that the technology worked. Provided the printer stuck to the agreed configuration, Komori would guarantee that the technology would work.

H-UV is built around the single tuned lamp and the Japanese manufacturer has more than 250 installations worldwide. But now it is also touting H-UV L, as an LED approach. At the recent Igas show, there were three presses running H-UV L, including the flagship Lithrone GX40 with just a Lithrone G37 equipped with standard H-UV. “We have offered LED for quite some time,” says Komori Europe marketing manager Peter Minis. “It comes under the H-UV banner.

“We have received a lot of interest and there are installations in Europe as well as in Japan. It gives the customer options when exploring low energy UV and according to the customer requirements and wishes. What we find mostly is that people that are interested in high added value work are interested in H-UV while if only printing four colour many prefer the LED option.”

The cost of varnishes and special colours has an impact on this line of thinking. Coatings especially are generally more available and of better quality for the single mercury vapour lamps systems than for LED.

Another approach will be to reframe the debate. Do not compare the cost of LED UV inks with the cost for conventional oxidising inks, but compare instead the cost of LED UV ink to the digital click. With a fast set up press running minimal make ready, the LED UV press is capable of taking on digital. At an SRA3 format an LED machine can more than match a digital press for speed, there is no question about print quality and it can print on a full range of materials.

Admittedly a litho press will never be printing variable data in the way a digital press can, but nor does it carry the same monthly maintenance charge and need to deliver an agreed volume of clicks. “We think an LED UV B3 press can be the most reliable, most productive and lowest cost digital press,” says M Partners joint managing director Murray Lock.

The company is UK distributor for RMGT presses in the UK. The RMGT 9 series, its SRA1 machine, has proven to be the most popular LED UV press in the market with up to 20 presses in operation, including some multiple installations. Marstan Press moved from a B2 long perfector installed to offer a cost effective fast turnaround for print to a five-colour SRA1 RMGT 9 LED press and has shifted its business model towards value added printing, using the fifth unit to print specials and offering foiling on the finishing side.

The cost of the special colours however can be even more expensive. Metallics are now available, but will still need care in printing while PMS colours can be margin destroyers. Paul Jaffray, Oliver Offset, says that one customer found this to his cost. The specifications for a job changed but it remained on an LED press. The cost of the special destroyed the estimate and the margin in the job. Pricing needs care.

Oliver Offset looks after Sakurai litho presses in the UK. It was the first press supplier to bring LED UV to the UK with two machines for B&B Press in Rotherham and others subsequently. He will also retrofit LED UV to both Sakurai and other presses.

“There is a bit of a trend now to convert one press, but not always the second,” he says. “This takes away concern about the price of the inks. The second press can be converted at a later date.” The ability to finish immediately is the big appeal he say. “Users can print, cut, invoice on the same day.”

It is about how the company is presenting itself to customers. If the message is about price, LED is probably not the solution; if it is about service, then LED may be the answer. And more and more people are seeing LED UV as the answer. There is a steady business in Baldwin retrofits for Jaffray to work on, not only in Sakurai machines, but equally those from other manufacturers. One that is underway is a Drupa 2000 generation Speedmaster CD102.

Companies that are looking at this route he says should be aware that rollers, washes, blankets as well as inks and plates will change. “That is what I point out. Success is about what happens after the lamp goes in,” he says. It’s about the complete package and working with trusted suppliers whether for a new press or reviving a machine that has perhaps lost its competitive edge.

This has led more and more printers to consider a retrofit route to bring a press that is not encumbered by financing up to a new specification rather than risk a press investment in a press that can print faster in a market that shows few signs of wanting more print.

It is not just litho where LED UV is making an impact. In wide format inkjet there is a huge swell towards LED. The cool running of the LED offers advantages in being able to print heat sensitive substrates, the digital nature of the technology allows users to switch off on bi directional print head shuttles or when the press is not working, and there is concern that the next wave of regulations from Europe will lead to outlawing more mercury containing lamps.

LED finds its way into packaging

UV flexo is the next area considered ripe for conversion to LED. And then comes inkjet and wider width flexo.

The same drivers, combining substrate, environmental concern and potential regulation, will drive the market in other sectors of print, with UV flexo presses the next in line. To date few printers or manufacturers have committed to the technology. A label or packaging press will have multiple drying stations, piling on the cost for a packaging print business. Companies like Comexi and Uteco are exploring LED UV while Mark Andy has made a full commitment to the technology.

The US company has been installing machines across North America. There says Phil Baldwin, printers are converting from water based flexo and missing out the step into conventional UV, instead going for the newer technology. Europe has been much more committed to medium pressure mercury lamps than LED.

“The second generation UV ink sets that are now available can run with either technology,” Baldwin says. And lamp suppliers, IST and GEW in particular have developed systems which can work with either technology. A print company can invest in a mercury system today knowing that there is an upgrade path using the same power cabinets and control systems. It takes just a few minutes to switch from one to the other on a narrow web press where the lamps can be positioned close to the web and clipped in an out as required.

A big advantage for Mark Andy is that the LED lamps is instantly on and off as needed. There is no warm up time, no cool down, with the digital version. There is also no question about degradation of the lamp’s effectiveness reducing the amount of energy delivered and resulting in only a partial cure. For food packaging the knowledge that a full cure has taken place is key says Baldwin.

Nor he says is there any reason to switch between the approaches. “A few years ago the choice of technology made a difference, particularly over the choice of photo initiators, the coatings and the formulations of inks,” he says. “That’s basically gone now.” But the price of coatings in particular is strangling their uptake. “One of the ink manufacturers told me that there are 300 coatings in the portfolio for UV and only four for LED UV, because there is simply no demand.”

He likens the market currently to that for electric vehicles, Today LED UV is like an electric car, is in the minority, but fast forward 10-15 years the market will be completely different. This is why suppliers are offering hybrid and upgradeable systems.

They are also starting to offer air cooled systems, at least for narrow web applications. These are much simpler than water cooled alternatives and will bring down some of the complexity, if not the cost. What is likely to have an impact is further consolidation and moves to standardise production on a common platform for customers with a worldwide presence and wanting the assurance that this can bring.

Gareth Ward

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Looked after by Oliver Offset, Sakurai was the first manufacturer to install LED UV presses in the UK with two for B&B Press in Rotherham. It has retro-added LED to a number of presses in its installed base.

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