Inkjet printing - when does the revolution start?
Posted in Features on January 09, 2013
Sometimes you can have too much of a good thing. A perplexing choice of some 30 different models and nearly as many suppliers confront converters planning to adopt single-pass inkjet printing. Products that range from roll-to-roll platforms to stand-alone modular presses, as well as hybrid flexo/inkjet presses, add another layer of complexity. Buyers understandably may have Darwinian thoughts about who will still be around to support their chosen press some years from now. With some heavyweight players involved, that's anyone's guess.
What is certain is that behind some extensive hype the inkjet market appears to be just treading water. Mark Alexander, Xaar's director of marketing, agrees: ‘The market has not grown as fast as we would like, yet we have seen digital printing as a whole become widely adopted for labels and packaging. The low rate of penetration probably reflects a wider lack of understanding about inkjet's attributes. Perhaps some converters feel the cost advantages are not compelling enough, especially when there is some ambiguity over ink costs.’
Of course, it's not all bad news. A few vendors have made some impressive sales against a generally depressed economic situation. But then again, their target market of primarily short-run self-adhesive labels remains relatively buoyant. Furthermore, inkjet’s penetration by digital technology has opened up new types of added-value opportunities, notably versioning. Aided by on-the-fly changeovers, a single job run may include labels carrying differentiated graphics, text and variable data. As a global growth area, it allows brand owners to develop seasonal, promotional or niche marketing campaigns, while retaining brand integrity. It also covers areas of regulatory compliance where labels and packaging must accurately incorporate the required regulatory information.
The much closer integration of front-end file handling within the full production workflow has enhanced inkjet's contribution to this market. As with digital printing in general, it contributes to faster press set-ups, quick job turnaround times and lower waste. The more advanced presses allow integration with management information systems that support sales and order processing modules. In a mixed production plant this can allow users to usefully free-up capacity on their conventional presses.
Print-head advances
Piezoelectric drop-on-demand printheads are the key to effective single-pass inkjet printing. The OEM manufacturers have concentrated on achieving smoother gradations and broader tonal ranges to boost print quality levels using a variety of proprietary techniques. Notwithstanding certain differences in gloss levels and color densities, they allow good inkjet printing to compare favorably with UV flexo printing. The same printheads have raised print speeds to around 24 m/min, or double that rate depending on imaging resolutions, grayscale levels or the number of interlaced printheads.As example, the ubiquitous Xaar 1001 printhead has a native resolution of 360 x 360dpi, but eight grayscale levels provide a higher apparent resolution of 1,080dpi. It uses so-called Hybrid Side-Shooter technology, which fires dynamically-variable drops from the nozzles to widen tonal ranges and allow the ink to flow directly past the back of the nozzles. Xaar's patented TF Technology is said to give a consistent, temperature-controlled flow rate and recirculation of ink within the head.
Kyocera's KJ4 piezo printheads print paper or filmic labelstocks up to 50 m/min (164 ft/min) with four grayscale levels or 75 m/min (246 ft/min) with three grayscale levels. Domino Printing Sciences has adopted them for its N600i modular label press, developed and manufactured by Graph-Tech AG, which it recently acquired.
Konica Minolta's UK technical partner, Industrial Inkjet, claims the new KM1024i reaches 80m/min at 360 x 720dpi using three grayscale levels. Beta tests using the next-generation KM1800i have resulted in even faster speeds with a 600dpi resolution. New 108-mm wide printheads allow the seamless stitching of fewer printheads across the web. In fact, wider web widths – commonly to 330mm or 13 inches – characterize the latest top-end modular presses.
Besides CMYK, the latest UV-curable ink sets more widely include opaque white inks, as well as orange and violet or orange and green. These extra colors give an expanded color gamut option, allowing users to produce up to 90 percent of individual spot colors from a standard Pantone color palette. Users also report good translucency levels for these inks when printing metalized substrates.
Where ink is concerned there are usually some caveats. Says John Corrall, managing director of Industrial Inkjet, ‘White printed by inkjet is OK, but only selectively. It's always cheaper to print the white by flexo if you just want a He adds that color gamut has become a big issue: ‘Most label customers now “test” us by demanding we print a whole bunch of Panton colors. And this isn't easy with CMYK. However, the ink suppliers are improving the gamut. Adding more colors is probably the main theme during the next year or so. The problem is simply that it will increase the cost of buying such machines.’
The wider adoption of UV LED curing is causing some interest. Once confined to inter-color curing, or pinning, before a conventional UV cure, full UV LED curing has begun to appear on some presses. Compared with conventional mercury-based UV lamps, LED's medium wavelength lamps use far less energy for ozone-free systems that are ideal for printing heat-sensitive substrates. They require dedicated inks and coatings, but simpler chemistry should make them cheaper with wider acceptance.
Some top-end models
With three product ranges, EFI Jetrion dominates the stand-alone market. It has taken an end-to-end approach with the 4900 series. Instead of off-line finishing with die cut tooling, models come complete with a dual-head laser die-cutter from SEI Spa. The line also includes matrix removal, inline corona treater, slitter module and twin spindle turret rewinding. As with all Jetrion models, it is fitted with Xaar 1001 printheads. The 4900M-330 is the latest variant, with a 13-inch web width.Interestingly, Sean Skelly, vice president and general manager, says serious buyers are now more likely to look beyond the basic specifications: ‘They want an inkjet partner who can help them understand and keep up with the fast-changing world of inkjet technology, and apply a complete production solution. By offering a vertically integrated approach that includes presses, ink, software, color management and system we can differentiate ourselves from competitors.’
Stork Prints' DSI modular press offers CMYK, white and violet and orange, as well as a primer. The press has LED UV for interdeck pinning, with a final UV cure augmented with a water-cooled chill drum. The DSI can run with Stork's Rotary Screen Integration (RSI) technology. Printing at up to 720 sq m per hour, it delivers resolutions of up to 1,000 dpi, as well as 3D effects that resemble screen printing. The company won the 2012 Label Industry Award for Continuous Innovation. An advertorial with more details can be found on page 32.
Durst's Tau 330 prints up to 48 m/min on a web of 330mm wide. Opaque white, plus orange and violet, are color options. The RIP software incorporates substrate and color management. The Tau 330/200 version has a web width of 200mm, and also uses Xaar 1001 printheads. The Tau 330 Variable Data Print option allows users to insert reels of die cut and pre-printed labels, while printing at the same rate as the host press. It can be integrated with Durst's Rotoworx 330 off-line finishing module with semi-rotary die-cutting.
Heidelberg's Linoprint L (formerly the iTS600 from CSAT) uses Xaar 1001 four-level grayscale printheads to deliver a 600 x 600dpi resolution with four print widths up to 420 mm at speeds of up to 48 m/min. It features Phoseon's LED curing system and can either be operated as a standalone machine or integrated into packaging lines as a separate system with a feeder device. It includes variable data and anti-counterfeiting features.
The Caslon hybrid concept developed nearly six years ago by Nilpeter and FFEI now comes with a White or spot color unit for placing before or after the CMYK Caslon print engine. It runs with webs up to 410mm at resolution-dependent speeds of 25m/min or 50m/min using Xaar 1001 printheads. Nilpeter typically sells the Caslon as part of a hybrid press with FA-4 UV flexo print units, die-cutting and other finishing units in web widths up to 420mm. FFEI offers the stand-alone version of the Caslon using Nilpeter's FA Line web transport system.
The latest hybrid is the d-Flex from Focus Label Machinery, which prints CMYK with White at up to 50 m/min using Konica Minolta printheads. LED UV curing allows printing on clear and metallic films. The servo-driven press comes in widths of 142mm, 250mm and 330mm with the usual inline finishing options for either roll-to-roll or roll-to-sheet delivery.
Finally, as a multi-pass press, Epson's high-end L-4033AW is an anomaly. It also uses a water-based pigment ink set for printing CMYK, White and Orange and Green using Epson's micro piezo, thin film printheads. The print quality is high, but production is slow. In a way it exemplifies the sheer variety of inkjet label presses available globally, as mentioned earlier. Furthermore, Epson is developing its own single-pass press, the SurePress X, which may appear in 2013 fitted with a full LED UV curing system.
Pictured: The Domino N600i features Kyocera's KJ4 piezo printheads for printing on paper or filmic labelstocks up to 50m/min (164ft/min) with four grayscale levels or 75m/min (246ft/min) with three grayscale levels
