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The development of affordable LED technology for UV-curable printing systems has continued apace for more than a decade, with few manufacturers now denying its benefits over mercury vapour lamps. With more and more customers demanding more environmentally friendly output together with lower prices, any investment in the printroom this year should be with LEDs in mind.

Just the somewhat Victorian words 'mercury vapour' may be enough to put off eco-conscious print customers when the clean-sounding 'LED' is available elsewhere. But the numbers stack up too: thanks to LEDs' ability to direct energy more efficiently into curing rather than heat, the overall power consumption is significantly less than that used by mercury lamps.

Comparing its own systems, EFI VUTEk states that switching to LEDs could reduce a wide-format printer's energy use by 75 per cent – the LED technology used in the VUTEk GS3250LX gets through around 3.6kW per hour, while the VUTEk GS3200's four mercury vapour lamps consume around 15kW per hour, or 9,000 kilowatt hours of energy each year for LED versus 46,800 for mercury vapour for those businesses running a two-shift, five day week - with an average cost of £0.15 per kilowatt hour at UK standard rate, that is an annual saving of nearly £6000 in electricity alone. Comparing the exposure system of metal halide lamps (mercury vapour lamps with added metal halogens), Mimaki estimates that MH can use as much as 15 times more than its standard UV-LED curing unit.

Moreover, Mimaki – creators of the first LED UV printer, the UJV-160 and maker of UV-LED systems including the JFX-1631 and UJF-3042 – also points out that LEDs offer lower energy consumption due to their instant-access approach; MH lamps must cool down before they can be switched on then heat up again before use, and therefore tend to be left on semi-permanently, while UV-LEDs can be turned off between jobs and reactivated almost instantly when needed. This level of 50 per cent use equates to consumption of more than 30 times as much energy by the MV system compared to UV-LED.

Among the chief benefits of the latest breed of UV-LED printers promoted by their manufacturers is versatility. Belgium-based digital print business Triakon adopted UV-LED curing in the form of an EFI VUTEk GS3250LX and found heat-sensitive and thinner materials were suitable for printing without head strikes or buckling with the 'cool cure' technology. Fellow VUTEk user BCF Digitaldruck und Mediengestaltung of Remscheid, Germany found that hard PVC of thicknesses as low as 0.2 to 0.5mm were now printable, while fewer stable panels like hard foam PVC panels were subject to shrinking or expanding due to heat exposure. The latter company also claims to achieve good results with laminated corrugated board, due in part to losing the need for a strong vacuum; a lower heat means the printheads can be lowered onto the substrate.

Using thinner, and therefore more lightweight, materials also reduces costs – EFI VUTEk user PVS In-Store Graphics reports savings its customers 30 per cent on the lower cost of materials plus an additional 30 per cent on shipping, as the business can roll up its work rather than transporting it in flat boxes. EFI adds that recycled materials can be used more readily too, again appealing to environmentally conscious consumers, while Mimaki highlights the business advantages in adding more unusual substrates to printers' portfolios, such as wood, plastic and 3D objects.

LEDs also last longer than mercury vapour lamps, to the tune of a 20,000-hour lifetime compared to under 2,000 hours, meaning less downtime and lower costs. BCF Digitaldruck und Mediengestaltung reports changing the mercury lamps on its previous VUTEk GS3200 up to five times a year at a cost of $4,000.

Triakon are one of a number of EFI VUTEk users who are realising significant commercial and financial gains from the switch to LED UV curing. Read ourTriakon case study here.

Time savings also apply when wait-time for prints to dry following mercury vapour curing is eliminated; LED-cured work is touch-dry on completion as well as insoluble, meaning it can be rolled up straight off the bed to save space, or can be printed on again – for instance in layers for tactile printing.

Whilst UV printing is not without its disadvantages - operators can suffer skin conditions such as dermatitis if in direct contact with UV ink before it is cured, and UV light can cause damage to eyes - manufacturers have eliminated dangerous ozone and volatile organic compounds (VOCs) and therefore the necessity for major ventilation, which is perhaps another perfectly viable reason to consider the upgrade to current and safer LED UV print technology.

In all, the benefits of LED curing compared to mercury vapour or metal halide lamp technology are too numerous to ignore. Healthier and simpler to use for operators, with cost savings and environmental pluses that can be passed on to the customer, the equipment currently on the market is definitely worth investigating.

Further reading...

1. LED curing and high productivity makes VUTEk GS3250LX the 'obvious choice' for Triakon

2. Mimaki White Paper - Why UV-LEDs are revolutionising ink jet printing

 

 

Ian Turnbull, Operations Director at Sihl Direct UK, discusses the importance of selecting the right media for the right application.  In this article, his focus is on roll up and pop up displays...

"You would be right in thinking that there is very little difference between roll up and pop up displays. They are virtually the same, except that with roll ups the retraction is normally done by rolling the media away, whereas with a pop up, it is usually folded down.  Both types of advertising are a must for companies wanting to be permanently present in the market.

To get the best out of either version - roll up or pop up - the display needs to be printed on the right material.

The opacity factor

Simply put, the higher the opacity the better, when it comes to roll up and pop up banners. A banner with 100 per cent opacity allows absolutely no light through, which means customers get a much clearer look at the display than one which is letting in light. This is why Sihl‘s products are usually equipped with a grey back which blocks out almost all backlighting.  However, Sihl does offer alternatives to the grey back. The Mirano POS Photo Paper PE 220 satin 3674 has a white back, but contains an opaque film in its composite structure, which also enhances the paper‘s edge tearing resistance. This means that despite the thinness of the paper, an almost perfect opacity of 99.8 per cent is achieved.

Colour consistency

When using roll up and pop up media for an exhibition stand or something similar, a combination of stiff and flexible print media is often required. 170-220 μm thick films are usually used in roll up systems. For pop ups, a more rigid 300-450-μm material is needed in order to guarantee enough stability. Different media usually produce different whites and colour rendering in the printed picture. Even when colours are properly managed, an inconsistent overall picture is unavoidable. For this reason Sihl offers product groups with identical coatings in a variety of thicknesses.

Curling

No one wants their pop ups and roll ups to curl.  Ideally, the edges of a print remain absolutely flat and neither curls forwards or backwards. The way the material has been stored and transported can affect whether it curls or not, as can the structure of the material. For example if the components react differently to changes in temperature and humidity. Polyester or rigid PVC based Sihl media barely react to environmental influences and usually remain perfectly flat.

Scratch resistant

These kinds of displays are often used several times and in different places so inevitably they are exposed to a certain amount of wear and tear. Ideally, a pressure sensitive lamination is applied to these products for protection against damage, but this not only means additional expense, it can also cause one sided tension on the front. Sihl media, especially films developed for solvent inks, are extremely scratch resistant and are therefore suitable for use without additional protection. The SuperDry Roll-up Film 190 satin 3471 and Mirano POS Photo Paper PE 220 satin 3674 in combination with pigment inks, are also highly scratch resistant thanks to their satin surface texture. Therefore they are suitable for use without additional protection.

Something all these films have in common is that with or without lamination, they are significantly less expensive than the products which combine a laminate layer, print medium and reverse side light barrier. Above all, ply bond strength and printing quality are significantly better with Sihl’s products.

Whether the display needed is a roll up or pop up, Sihl Direct UK can offer the most suitable media for the right use."

About Sihl Direct

Sihl Direct UK is part of the global Diatec group. The company is a leading coated media provider for the large format printing industry. In addition to media for the latest generation of digital printers, Sihl Direct sells a wide range of media for photo, office and large format applications.

For more information, please visit www.sihl-direct.co.uk