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Technology

Embracing the Challenges of Digital Print Finishing

by Staff

May-June, 2011
Market demand for short runs, quick turnarounds and variable data has led to an explosion in digital print. It’s no surprise that finishing processes have required adjustments to match the changes being seen in the world of print, and in-line or near-line finishing options are popping up from industry manufacturing partners.

While some printers are attempting to enter the market with equipment that allows the finishing to be done onsite, digital print brings its own production challenges to the finishing process. For this article, InsideFinishing consulted with Roy Oomen, from Hewlett Packard (HP), David Hutchison, BrightMARKS, LLC and Mark Coalson, Transilwrap Company. Oomen, Hutchison and Coalson provided their insights on the future of digital print finishing, addressing the challenges that come when adding specialty finishing services to digitally printed products. Challenges when finishing digitally printed sheets: printers
Preparing a digitally printed product for finishing must start at the beginning of the process – with the printers. Roy Oomen at HP explained, “The first issue we see over and over, especially when it comes in a sheet-fed workflow, is that printers need to control the accuracy for cutting down the sheets. At HP, we keep registration aligned either by leading or trailing edge and once we have straight sheets that are cut straight, it becomes a much more manageable process.” Oomen said that once passed to a trade finisher, sheets that were not cut straight can lead to increased waste, which can be incorrectly blamed on the finishing process. “The printers are assuming that the sheets are delivered cut straight, and that’s often not the case.”

David Hutchison of Kansas City-based print finisher BrightMARKS LLC, agreed that the sheet registration system can present a challenge in finishing work. “Most of the installed base of digital machines are sheet-fed machines, and none of the sheet-fed digital machines have an ‘active’ side guiding or sheet registration system that ensures that the position of the print relative to the edge of the sheet is consistent from one sheet to another.” Hutchison continued, “All production-quality hot stamping machines have an active side guide system. This ensures that each impression of the stamped or embossed image is in the exact same position, relative to the edge of the sheet, on each sheet of paper. When you combine the two processes of digital sheet fed print and stamping or embossing, the position movement of the digital print on the sheet reduces the yield of quality registered sheets.”

Hutchison explained that the minor movements can be dealt with by paying attention to the design elements to avoid tight-register graphics; spreading the stamping images to cover the movement; creating more trap over the print where color shifts occur and, in the case of embossing, choking the image down to avoid tight-edge register.

Challenges when finishing digitally printed sheets: finishers
Once the printed sheets arrive for finishing, additional steps can be taken to ensure a smooth process. First, according to Oomen, is an awareness of the correct coatings and varnishes for use with digital print. “Whether the finisher is UV coating, or even debossing or stamping, with a spot pattern coat, it is important to work with the coating and varnish suppliers,” said Oomen. “They all have lists now for coatings that work well with digital.” The suppliers have knowledge based on prior print jobs that should be referenced, since some coatings are more appropriate to specific digital processes than others. The key, explained Oomen, is to not assume that any coating or varnish can be used for digital print.

Additional challenges may be encountered when using scratch-off foil and digitally printed sheets. The underlying print may show through, and this is because of the changing surface levels of the print on the paper. “Most digital print methods use ink systems that ‘stand up’ or ‘sit on top’ of the paper surface,” stated Hutchison. “The change in level from paper to printed area causes a diffraction of light, making the underlying print visible. This can be addressed using screens in place of solid print for the underlying image or prize.”

In addition, toner can crack or ‘break up’ when embossed. This issue often is encountered when working with digital print from an older generation of toner-based machine. “The process of applying a hot stamped scratch off foil will sometimes make the toner brittle,” Hutchison explained. “The brittleness is caused by heat exposure during the stamping process. The result is that when the piece is scratched, the foil and the image come off.” With proper planning, this issue can be avoided by reducing the operating temperature of the stamping machine. Hutchison shared that the temperature should be as low as possible – even as low as 200°F if the machine allows. If a reduced temperature setting is not successful, Hutchison recommended switching the method of application to a silkscreen printed scratch off. “In all digital print projects, testing should be performed for the process of choice prior to the print actually taking place,” he said. “This will eliminate many production issues.”

Oomen offered an additional ‘fix’ for some digital finishing issues. “In a few cases, the finisher may want to reintroduce corona treating post-print,” he said. “That may seem counterintuitive, but when you look at total bond stretch, construction and durability, it may make sense prior to some converting and finishing processes.”

Adding lamination to digitally printed sheets
Laminating digitally printed sheets also can present challenges, but laminates have been engineered to meet the demands of bond and durability based on the printer technology. Mark Coalson with Transilwrap Company, Inc., explained, “For example, when water-based inks were introduced a decade ago, adhesives were designed to activate at a temperature lower than the boiling point of water. Otherwise, any residual moisture in the inks would outgas (or boil) when laminated and the print would be ruined. Many of today’s newer digital print technologies incorporate heated fuser oil toners to deliver the inks. Any residual oil residue can create problems when trying to laminate. Changes in laminates had to be made in order to counter these oily surfaces.”

Thermal lamination is engineered for robust, long-term use, according to Coalson, and in many cases, the type of thermal laminating film will depend on the type of digital printing system used. When laminating any digital print, the bond will be only as good as the ink or toner is bonded to the printed substrate.

Again, Coalson pointed to the printer as the first step in producing a successfully laminated digital print product. “The printer must understand the compatibility between the print technology and the substrate to ensure acceptable ink or toner bond,” he explained. “The enhanced adhesives offered today can help in bonding to the more difficult ink or toner technologies. Thorough testing of the ink/toner bond to the media and the thermal laminate bond to the overall graphic are the recommend steps to ensure a high-quality solution.” Laminate providers are best suited to provide advice and recommendations as to which thermal laminate is appropriate for the printing device.

The Future of Digital Print Finishing
The digital print market will continue to gain strength as more printers feel comfortable in making investments in a strengthening economy. Equipment suppliers are already beginning to react. “We’re seeing some of the finishing equipment suppliers integrate with each other,” said Oomen. “They are figuring out how they can run their machines in-line to make print and finishing more seamless. HP is playing a fairly active role in that by bringing everyone together at partner conferences.” The other trend that Oomen sees is on the web side, where configurations for combination print are becoming increasingly sophisticated. “The trend that we are seeing is increasing diversification in the sequencing of stations, the type of stations and the number of stations.”

On the sheet-fed side, Oomen has watched as finishing companies begin to understand that running digital work through a traditional finishing environment doesn’t make sense from a cost or efficiency perspective. “Companies that have tried pushing 80-100 jobs through their existing finishing set-up quickly see that digital business is very different,” explained Oomen. “Once their business ramps up to a certain level, it makes more sense to put in a dedicated digital finishing line.”

Jim Hamilton, group director for InfoTrends, concurred in a recent article for The Binding Edge titled, ‘Production Digital Print: Changing the Feeding and Finishing Market.’ “When digital print comes into the mix,” Hamilton wrote, “it often happens that print service providers continue with off-line finishing methods because those assets are already in place and effective, even if they are not particularly well suited to the short runs and quick turnaround of digital print.”

Troy Summers, Trade Print Finishing in Salt Lake City, Utah, noted that same complication when UV coating digitally printed projects. “Because digital presses can only print up to a certain size, many finishers are having trouble spot UV coating the smaller sizes on existing equipment,” he stated. To combat the problem, Trade Print Finishing has installed a smaller Sakurai press to better serve digital print jobs. “The Sakurai allows us to accommodate the smaller digital printing sizes, which is an advantage when registering those smaller sheets.”

Conclusion
In his article, Hamilton concluded, “Workflows that take advantage of digital print and in-line or near-line finishing are part of a larger trend toward optimization, automation and lean manufacturing. Printing has lessened in importance as it has become one weapon in an arsenal that includes other media. We no longer live in a print-centric world and yet print continues to play an important role because it’s physical, lasting and doesn’t require electricity to read. Digital print, in particular, is key, because it forces us to revisit the basic value of print in an electronic world.”

InsideFinishing would like to thank Mark Coalson, Transilwrap Company, Inc.; Roy Oomen, HP; and David Hutchison, BrightMARKS, LLC, for their input. To read the full article by Jim Hamilton, visit www.thebindingedge.com.