UV WEB OFFSET PRESSES -- Finding the Cure
BY CAROLINE MILLER
Improved press technologies, better ink formulations and the absence of environmental regulations are just a few of the reasons why UV web offset press designs are turning the heads of heatset web printers.
In the past, a heatset printer might not have considered a UV web press as a viable option in the pressroom. The cost and the complexity alone of UV printing outweighed any benefits a printer could gleam from printing and drying/curing with the UV process.
"Had anyone predicted five years ago that the UV market would be where it is today, they would have been met with scorn," admits Robert Pitel, vice president of sales and marketing for Sanden USA. "It is now feasible, if not increasingly common, to run at sustained speeds in excess of 1,000 fpm. This was impossible five years ago. Holographic printing, short-run magazines, and much work previously the domain of sheetfed equipment are now run regularly."
Andrew Fetherman, manager of the Muller Martini press division, agrees, adding that the improvement of UV ink has had a major impact on the UV press market.
"Not too long ago, UV inks offered a very small window of operation. Ink/water balance had to be extremely precise and toning was a recurring occupational hazard. But over the past few years, the ink manufacturers have made a huge investment to perfect their UV products. Now, they're easier to run and provide a bigger window of operation," says Fetherman.
But it is not just ink that has improved over the 30 years that the UV process has been available to the graphic arts industry, explains Frank Roberts, vice president of sales for Didde Press Systems by Alcoa Packaging Machinery. "The inks have made press manufacturers develop presses that are also more compatible with UV inks."
Because UV inks are sensitive to press-generated heat, temperature fluctuations make them break down, which affects printability. But, new press technology has taken care of that problem. The new generation of presses feature full cooling of ink trains and the web itself—so everything is kept at the optimum temperature. Maintaining the temperature in the proper zone has also helped eliminate ink breakdown and all the problems associated with it.
Since the UV process has gotten easier to use, and the new generation of presses offer the same advancements that are reducing make-readies and increasing the speed of conventional heatset web configurations, UV presses are now easier to run and much more productive to operate.
The primary benefit of UV over heatset printing is the flexibility gained in running in-line presses versus blanket-to-blanket presses, reports Pitel. "With in-line equipment the customer gains in his color combinations. For example, on an eight-color heatset web press the printer must run the color placement that the dryer layout dictates. With UV, the customer can run five-over-three colors, six-over-two, etc.," he states. "The UV process holds an inherent advantage when teamed with its most common partner—the hard cylinder (blanket to impression cylinder) webs.
"Through interstation drying (i.e., drying the ink after each print unit), a wider variety of color combinations can be achieved by simply inverting or perfecting the web where required," Pitel adds. "For instance, while a five-unit (10-color) heatset perfector is capable of no more than five colors per side, a UV equipped 10-color in-line hard cylinder web can print five-over-five, seven-over-three, or even 10-over-0," he reveals.
Another UV advantage becomes most evident in direct mail applications, where post-processing is a critical component. First, UV inks are instantly dried to allow for immediate personalization via laser printers. Second, UV eliminates web shrinkage caused by the intense heat found in the typical heatset drying process, the result of which can affect fit between the printed material and the personalized message. Finally, because the UV process does not remove much of the web's moisture, cracking in an off-line folding process becomes much less of an issue than with heatset work.
An additional benefit of the UV web press that many printers may not consider is the lack of space that a press takes up, points out John Sillies, executive vice president of GSS. UV allows for reduced floor-space requirements resulting from the compact size of UV equipment versus the large post-dryers and chill stands. Muller Martini's Fetherman agrees, noting that big heatset presses take up a lot of costly real estate on a printer's pressroom floor.
All of these press technologies coupled with no environmental restrictions make UV presses a tough new competitor. The environmental advantages are substantial, adds Sillies. "There are no volatile organic compounds (VOCs), unlike solvent-based inks and, depending on the state and local agencies, special permits and control devices are generally not required."
And because of the lack of VOCs, UV drying is an easy transition for coldset web printers looking to expand their operations, notes Eric Short, president and CEO of RDP Marathon. "In operations that do not currently have pollution control expertise or the inclination to deal with equipment and regulatory issues, UV is an easy move from coldset offset printing," he states.
At the vanguard of this trend toward UV web printing has been California heatset printers, notes Fetherman. "They face more stringent anti-pollution laws and they tend to be at the forefront of national trends."
Also of interest to commercial printers, particularly those that are incorporating variable printing, is UV's ability to dry instantaneously.
"Until recently, the most natural fit for UV has been the direct mail market," claims Pitel. "The ability to dry ink for immediate post-processing, as well as having a cured product impervious to the heat of lasers, has resulted in rapid growth. In addition, since most direct mail applications already involved the use of hard cylinder webs, UV was the only effective process for drying coated stock with various color configurations."
As the demand continues to increase for highly personalized pieces and towards faster turnarounds in general, the benefits that direct mail printers have long enjoyed are now being coveted by others. "Variable data personalization is much more effectively produced on a UV web press," explains Fetherman. "Because the ink is instantly cured at full quality as soon as the lamp hits it, you can add ink-jet or laser personalization immediately."
Ink Prices Need to Drop
Still, there is one drawback for many—ink prices remain prohibitive to some. Even so, the costs are coming down. "As more and more printers switch over to UV inks, the cost of the inks should decrease and the advances in chemistry should accelerate. The technology used to dry the UV ink has made great advances over time and we would expect the improvements to continue for years ahead," remarks Sillies.
Fetherman agrees. "As the cost of UV ink comes down, we're going to see the use of UV in many more applications. For example, the publication printing market—with its inserts, outserts and glossy covers—is an ideal candidate. Direct mail will always be strong. But the fact is, anything that you can run on a heatset web or large sheetfed perfector can be printed on a UV web press."
With all the advantages that UV can offer, what are some of the features in a UV press for which web printers are looking? "Customers are looking for lower capital expenditures versus a heatset configuration; a shorter and simplified web lead; versatile web leads for various print configurations, such as five-over-five, six-over-four, etc.; as well as flexibility for web leads for coating applications," reveals RDP Marathon's Short.
The critical features needed for a UV application is the ability to run at press speeds with consistent quality. This is achieved through the design of inking systems that are compatible with the higher tack of UV inks. Over certain speeds, generally defined as 800+ fpm, chilling of vibrator rollers is a necessity. Chilling of fountain solution is also a plus, giving a more stable environment in which to print, according to Fetherman.
Temperature control over the entire printing process is another feature, he says. "We now offer chilled ink rollers, as well as chilled bay/idler rollers, to cool the web continuously—from the splicer to the UV lamps. When you control the environment of the UV process like that, the inks stays cool so it performs optimally and you can run at higher speeds. You wind up with more consistency, higher quality and improved productivity," Fetherman continues. "Some of our customers actually heat the rollers at the beginning of a job, then cool them once the web starts generating heat to ensure that every impression is made under the optimal conditions."
Sanden says its customers are looking for full programmability of the press in order to turn an otherwise daunting task of controlling print quality into a relatively simple and manageable process.
"Traditional web presses typically do not have this ability. The second key—no different from all press technology—is a fast makeready and low waste," Pitel says. "The third criterion is the increased need for a powerful ink train to allow the heavy coverage requirements of commercial applications, yet with a design specific to the requirements of UV ink."
So, with so much going for it in terms of technology and productivity, the future of UV web printing appears bright indeed. "You'll be seeing UV webs used to produce a growing number of printed products across the board," concludes Fetherman.
"The environmental issues with heatset and advancements in UV inks and UV press technology make the process an attractive alternative, especially for the publication and newspaper markets."