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Not just for rigid substrates, UV-curable printers offer some distinct advantages when printing to roll materials. Following are the benefits, plus some tips and tricks for working with roll materials on a UV-curable printing system.

By John Crumbaugh

UV-curable inkjet printers are being widely accepted by print shops that invest in the technology to streamline their production process and reduce their dependence on lamination and post-print dry time for their rigid signage.

UV-curable is an extremely effective way to produce quality prints on goods such as Coroplast, foam boards, PVC, aluminum core panels, and plexiglass, just to name a few.

These materials can be printed, cut to size, and immediately ready to deliver to the customer. For this reason alone a UV-curable printer makes sense to many shops looking to improve their profitability. However, there is another reason to make the move to UV-curable… roll-to-roll printing.

Rolling with UV-Curable

Conventional wisdom states that a shop with solvent or aqueous printing capacity that then adds UV-curable to its business should do all of its banner and other roll-to-roll work on the existing unit and use the UV-curable printer exclusively for rigid printing. This is the practice in most shops having both units available and works well, but misses an important benefit that many hybrid (roll-to-roll and flatbed capabilities) UV-curable printers like the Legend 72HUV offer.

UV-curable printing is a great way to print long-lasting banners where outdoor exposure would lead many solvent and aqueous inks to prematurely fade. UV-curable inks are quite resistant to fading outdoors, have no need for lamination to protect the graphic, and do not weaken the substrate like solvents do.

Many different types of roll-to-roll materials can be printed using UV-curable without the need for custom ICC profiles. This ability allows for the rapid change of roll materials and the added advantage of high-quality output on more custom materials, such as dreamScape Wallcoverings for décor work.

As a case in point, at LexJet’s recent 2008 Technology Review open house, the Legend 72HUV printed on 26 different roll materials in the course of two days in order to produce samples for the show. All samples were printed using the same mode and color set. The color of the graphics was consistent across the board, with the only real difference caused by the texture of the materials.

UV-curable inkjets have the ability to print on materials such as wallpaper, some synthetic fabrics and many types of uncoated specialty vinyl. Materials such as uncoated Tyvek and other environmentally-friendly banner materials also work well with UV-curable inks.

Using a UV-curable printer for this wider array of roll materials can increase the value of the products produced and open up new, profitable markets while making these products easier on the production staff to produce quickly without the make-ready required when using solvent inks. Magnetic material also works well with UV-curable, so that magnetics can be printed without the need for lamination.

While many UV-curable printers offer roll-to-roll capacity, it should be noted that all UV-curable printers are not created equal in this capacity.

Printers that have a roll-to-roll system engineered into the system from the start, and not as a bolt-on option, will outperform units with a bolt-on attachment.

Units that have dancer bars or tension rollers in addition to just a take-up roll will also perform better with a wider array of roll media.

Roll-to-floor type units without dancer bars or tension rollers will only handle a few materials and perform rather poorly in a production environment.

The best units for roll-to-roll printing will feature an adjustment to the grit roller pressure in order to handle lightweight materials, an adjustable platen vacuum, and heavy-duty in-feed and out-feed systems that can hold over 100 lbs. of weight without distorting or flexing the bars.

In the case of belt feed systems, units having multiple vacuum zones, hold-down bars, and adjustable feed and take-up motors will produce the best results. Make sure to ask about these features, and whether or not they’re included in the printer when you start searching for the right UV-curable printer for your business.

Before You Print

There are some important things to consider when printing roll materials with a UV-curable printer. First, can the material take the heat generated by the UV lamps without buckling or changing dimension?

Many roll materials do not have a problem with heat, though materials like polystyrene do. Also, you should consider not only the printing surface but the backing material. Always consult with the printer manufacturer about materials that may be sensitive to heat.

Fabrics that contain natural fibers are not a good idea to print on a UV-curable printer as the ink can absorb into the fibers and not cure completely. Synthetic fabrics work well if they have a dense weave or a backing material so that the ink does not pile on the printing platen.

As noted earlier, specialty materials, such as magnetics, work well on a UV-curable printer. However, it is often necessary to fasten a sheet of plastic material such as Coroplast to the machine to act as an insulator so that the magnetic material does not stick to the metal of the printer. So, even though magnetic material comes in rolls, you feed it through as you would a rigid material.

While there are no real “tricks” to printing roll media on a UV-curable printer, the operator must adjust the media advance for each material and width as materials will react differently, just as they do with rigid media. Also, platen vacuum will vary for each material, so a quick scout should be done prior to beginning a production run to ensure that the material will lay flat, advance correctly, and not distort due to heat.

Finally, as with any roll-to-roll printer, the quality of the material will dictate success. The material, regardless of type, must be wound on the roll evenly, not damaged on the ends, or otherwise compromised. Materials should be properly stored to prevent damage, such as the use of a roll stand.

While all roll printing devices have the same need for quality, undamaged materials, the bulk of the issues that arise when printing roll media can be traced to poor media handling or shipping damage, which also holds true for rigid materials.

John Crumbaugh is vice president of technology for Digital Equipment Company.