Crises have a habit of throwing up new solutions or the acceleration of trends that were already apparent, but are now being applied with more urgency. Here we’re looking at how energy costs have changed the economics of ink drying so that the decade-old trend towards adopting UV-LED based curing looks like becoming a rush, especially as lamp costs fall and output increases. ROIs to convert conventional heat/IR driers or the older mercury arc UV lamps have fallen from periods measured in years, to months in some cases. 

Until now the adoption of UV-LED has been driven largely by technical issues, partly to do with output and particularly whether the lamps can be fitted to the print units – their lower power means that they need to be closer to the print surface than mercury lamps, and it also made them unsuitable for the fastest print processes. As output levels have increased, this issue is going away. 

Fujifilm, which has just introduced a retrofittable UV-LED system for narrow web flexo label presses, lists the benefits of choosing UV-LED, which would apply to any process, whether litho, flexo or wide-format. “Energy use is drastically reduced, VOCs are eliminated, and less waste is produced. The working environment for operators is also improved, with many undesirable factors eliminated, including heat from the conventional UV lamps, noise and even the smell. Material usage is also reduced, and the system requires less maintenance and labour.”

In addition, it says: “The system offers more consistent quality as the impact of the heat from the UV lamps is removed, resulting in better registration and less substrate stretching. In addition, colours are vibrant and easy to achieve with Fujifilm’s high-performance LED-UV inks, and the dramatic reduction in power required for the LED-UV lamps means substantial cost savings can also be made.”

Bluprint in Essex supplies retrofit LED-UV units based on AMS Spectral UV lamps, with ranges from 5-20kW systems. “Conventional UV takes time to power up and wastes large amounts of energy on producing excess heat, or an unnecessarily broad spectrum of UV light,” says Christie Harman, marketing manager. “AMS Spectral LED UV on the other hand, is a far more efficient system. The diodes are programmed in a modular way to switch on or off in-between sheets, or even to change the width of the drying required. There’s also no wasted warming up time, and the narrower spectrum of UV wave lengths produced are dramatically more specific.”

She cites a recent installation, on a six-colour Koenig & Bauer Rapida 106 litho press at J Thomson Colour Printers in Glasgow. With the AMS Spectral UV, it reported a decrease in energy consumption of up to 80%. 

The UK is blessed with a healthy population of UV lamp makers, serving a range of applications of which print is just one. Pioneers included Wallace Knight and Primarc, now part of Baldwin Group alongside the US Air Motion Systems (AMS). Other UK UV manufacturers tend to have former WK or Primarc employees among their management today. 

The original Primarc factory in Slough still makes mercury arc lamps and their associated components, but it buys in UV LEDs. We talked about recent development in the market with Baldwin’s UV experts Carsten Barlebo, European vice president for LED-UV, AMS Spectral UV, and Christian Schreiber, director of strategic accounts for Baldwin Europe. 

“AMS started this in Japan 10 years ago, with conversions based on quality,” says Barlebo. “In Europe the ink prices were a problem. But now the gas availability in Europe is under threat, it is more attractive. Also, the LED ink prices have come down drastically.” 

“If you have an eight-colour press with two mercury lamps, then LED would save a lot of money. Two years ago, this was less important, but it has changed with the high cost of energy. Apart from the lamps’ low consumption, there is also the factor of not heating the substrate in a gas drier, then having to cool it in chiller units and re-humidify it. This all takes power that LEDs do not need.”

Apart from energy costs themselves, Schreiber says that two major factors driving interest in UV-LED in Europe are anticipated gas shortages, especially in Germany; and the inconsistency of paper stocks following European mill closures.

So far, actual orders for LED retrofits are rare, Barlebo says. “There is a lot of talking, but we have only sold one retrofit in Europe, in Switzerland. We are currently working on a 48pp Manroland Lithoman web press in the US, which is going LED to reduce its carbon footprint. We are also fitting LED to a brand-new Koenig & Bauer B1 sheetfed at Windles in Thame. They bought LED for quality, and we are sub-contracted by K&B. We are also fitting LED to a brand new 16pp web offset press in the UK. But if the gas price keeps going up, then LED is the solution.” 

If Germany runs low on gas this winter, industry supplies will be restricted to maintain domestic supplies, says Schreiber. Baldwin’s UV-LEDs are powerful enough to allow web offset printers to switch from gas drying tunnels to LED-UV and run at up to 14m/second, though it’s a bit late to start for this winter. “Printers are forced to buy what [paper] they can, and sometimes store it in containers outside, in the cold. UV gives a higher quality, consistent finish on all sorts of paper.” One of the benefits of UV curing, whether mercury or LED, is that it works with pretty well any stock and cures with the same appearance. Mis-matching stocks don’t matter so much as with heatset, Schreiber says: “LED gives sheetfed quality on web stocks.”

GEW in Crawley is a major supplier of mercury arc and LED UV curing systems for narrow web flexo and digital presses, as well as wider flexo presses for flexible packaging. It has two families of UV-LEDs: LeoLED, which uses water cooling and chillers to support high output lamps, and since September, AeroLED, which is air cooled and only needs fans and ducting, but runs with lower power and narrower maximum lamp widths. 

“UV is vital in this sector, and GEW dominates it in worldwide sales,” says Jamie Neill, UK and Ireland sales manager. “The greatest switch from mercury arc is in narrow web, where energy costs shot up, so we see a lot of interest in LED. UV is also widely used in sheetfed packaging, for instant finishing. The greatest switch from mercury is in narrow web, where energy costs soared, so we see a lot of interest in LED. For a new press, UV LED is a minimal percentage of the total cost.”

GEW also offers a sheetfed unit as a result of Panasonic, which together with Ryobi (now RMGT) pioneered UV-LEDs for sheetfed litho, stopping production of its units in 2018. “RMGT wanted to replace Panasonic as a supplier, and GEW got the contract for sheetfed presses. We can also replace existing lamps,” says Marcus Greenbrook, international sales director. 

“We also sell them to Heidelberg, Manroland, Koenig & Bauer, Sakurai, etc. If we have not fitted one to a particular press before we will go in and measure the press in fine detail and make a 3D model, and then make the mounts, shields, etc. The second time we can use the same measurements. 

“Narrow web is less difficult than sheetfed. Sheetfed has grippers, blanket washes, etc, that can get in the way, so you need to be able to get in there and modify some parts, such as foot boards. On modern presses it is less necessary as they tend to have provision for UV. 

“We are doing a number of upgrades in larger groups from arc to LED,” says Greenbrook. “In the folding carton market there’s an ageing population of arc UV systems. Quite a few printers want to save energy by going to LED. There are enormous savings. 

“It’s the same for narrow web flexo. For commercial printers with coaters, and IR or warm air driers, they represent lots of maintenance and cost. We can replace with LED, or they can fit them on a new press.

“GEW arc and LED is interchangeable on the same system. We developed this six years ago, where the two systems can be swapped. The controls and the power supply remain the same to the lamp heads, so you just plug it in. At the time LED was expensive and the output was limited. But now the output is higher, and the costs have come down.”

Benford is a 30-year-old UV manufacturer based in High Wycombe. “We have been doing IR to UV retrofits for a long time, normally for a specific type of work rather than for energy reasons,” says managing director Marc Boden. “There are added ink costs, installation costs, etc. We have no experience of customers changing IR/hot air to UV purely for energy reasons. I do have people with conventional UV going to LED though – for instance one customers has converted seven or eight presses that way. Aztec Label in Kidderminster has had two presses converted to LED and savings were a feature of this decision.”

He says that dual UV, a mix of LED for colour inks and mercury arc for clear coatings, is most popular on sheetfed presses with coaters, either new or as a retrofit. “LED coating is still very expensive and not as good, not as thick, as the LED frequency doesn’t penetrate as far,” Boden says. 

Baldwin takes issue with this, as Barlebo says that its high-power LEDs can work with very clear coatings, though these do cost more, and thickness is restricted. 

Earlier this year Fujifilm entered the UV-LED market with a system designed to work with the Sericol Flexo JJ inks made in Margate by Fujifilm Speciality Ink Systems. The Fujifilm Activ Hybrid LED UV system is suitable for new narrow web label presses or retrofits from existing water-based or mercury UV installations. High-powered LED lamps are said to allow running speeds 30% faster than earlier units. There is also the option to mix the LEDs with mercury arc lamps.

There are still reasons not to use UV-LED. Some specific applications such as garments and primary food packaging can’t use UV inks for reasons of migration of uncured monomers. Powerful mercury arc lamps carry less risk of incomplete cures than weedier LEDs, while as Barlebo at Baldwin points out, so far there are more low-migration inks available for mercury wavelengths. 

Other than that, UV-LED is likely to be on the list of considerations for anyone specifying a new litho or flexo press, plus some types of wide format. The economics of retrofitting are also improving and will continue in that direction as energy costs grow ever scarier.