Offset Litho is Ready for What’s Next in Packaging
Offset lithography’s dominant share of the folding carton market and stable position in package printing overall is not simply owed to its long-established stake in the printing industry. It has earned its place toward the top through ongoing technological advances that have been well attuned to changes in market demand.
Press automation, in particular, underscores offset’s continuing relevance as a packaging process that can be challenged by other printing methods, but probably will never be dethroned by any of them.
R&D competition among offset press manufacturers has never been more intense, reflecting their understanding that only digitally controlled, near-fully autonomous printing systems will be up to delivering the levels of quality and cost efficiency that profitable package printing now demands.
Package printers are under constant pressure from brand managers for improved delivery, notes Clarence Penge, VP, sheetfed, Heidelberg USA. This is why they turn to their equipment suppliers for solutions that can help them relieve the pain points. As a result, he says, “it’s not us saying what you should buy:” it’s a collaboration aimed at designing the right press for the tasks at hand.
According to Walter Chmura, VP of technical sales for KBA North America, a member of the Koenig & Bauer Group, the company won’t sell a packaging press without first examining one to six months’ worth of the customer’s work for clues to how the press should be built. In this way, Koenig & Bauer can also help the customer develop the ROI information that a CFO or the bank providing the financing will want to see.
Where the Breakthroughs Are
As Doug Schardt, director of product management for Komori America, points out, there’s no single development responsible for elevating offset to the high place it occupies in package printing. But, there’s a strong consensus of opinion about the press features that customers find most valuable.
For Chris Manley, president of Graphco, a distributor of presses bearing the RMGT Ryobi MHI Graphic Technology brand, one of offset’s main attractions is its day-in, day-out productivity. An RMGT press that can makeready in 10 minutes, hold sheet waste to a minimum, and run at 13,000 sph can produce three times more work in a day than a green-button digital press that’s quicker to get started but slower to print, Manley says.
Many developments have contributed to making offset presses the nimble, precise platforms they’ve become. Some of them are things that lithographers have been striving to get right for years. Others stem from recent advancements in software, visual inspection systems and closed-loop quality control technologies.
An example from the first category is what Schardt describes as an ongoing effort to standardize inks on press, enabling them to reach a wider range of PMS colors through CMYK builds. Master that, says Schardt, and “packaging workflow efficiency will explode. Wash-ups and color changes will be minimized and pre-inking programs would be able to be used to their fullest potential.”
Streamlining the tasks of job setup and production is the leitmotif of almost everything taking place in offset R&D. It has to be, because as volume parameters change, the demand for increased throughput in packaging production only intensifies.
In many plants, shorter runs and jobs in multiple versions have taken their places in the queue with traditional long-run work — and the pressroom has to be equipped to handle them all with the same degree of efficiency.
Synonymous with press efficiency is press automation, which can vary in application from job to job.
As Chmura notes, a single long run is less dependent on automation for efficiency than is a series of short runs, with the washups, plate changes and color OKs that moving from one to the next entails. This means that a press must know how to cruise as well as sprint if it is to deliver the kind of automation that package printers will find useful.
Many press functions benefit from automation, but nowhere does it add as much value as when it drives the job changeover sequence. As one job nears completion, pre-stored instructions for the next job set makeready tasks in motion so that the interval between runs is minimized — along with the need for operator involvement.
Heidelberg accelerates complex makereadies with Intellistart 2, a software control system that carries out everything except the physical tasks that only a crew member can perform: for example, removing ink from a fountain. The software’s “Push to Stop” orientation keeps everything in continuous motion until the operator interrupts it.
Koenig & Bauer calls its job changeover solution ErgoTronic AutoRun. According to Chmura, this technology starts a fully automated job changeover as soon as the previous job is done and resumes production automatically when makeready for the next job is complete. The cycle repeats over and over, Chmura says, until the operator either cancels the auto-run function or everything in the prepared job list has been printed.
Pile In, Pile Out
The potential for increasing the number of jobs completed per shift is obvious, but for that to happen, something else has to be present: efficient press logistics, which Schardt defines as automated material movement into and out of the press. He says logistics systems are now regular additions to packaging lines, some of which have double and even triple deliveries to optimize material management.
Penge notes that when a press on a 20˝ elevation is running at 18,000 sph, sheet piles will have to be changed every three to six minutes — creating a great deal of extra work for operators, especially when the piles consist of heavy stocks. He says that speeding up the pile-changing sequence with the help of pallet conveyors and other logistics assets can increase net press output by 1,500 to 2,000 sph.
Nonstop sheet-handling systems at both ends of the press let Koenig & Bauer Rapida equipment keep production uninterrupted during pile changes at full press speed, Chmura says. In the feeder, digitally controlled servo motors raise and lower piles smoothly for problem-free feeding into the sheet stream.
The most advanced features for packaging production are usually found on presses with sheet sizes of 40˝ or larger. Full-size and VLF (very large format) machines have traditionally been the default for packaging work because of the layout flexibility and the high-volume efficiency they offer.
But as Manley observes, when run lengths decline, a 40˝ press with its crewing requirements and high operating costs may not be the most cost effective way to get the job done. He says that the short-run economy of the 24x31˝ RMGT 790ST Packaging Edition press positions it not only as an alternative to full-size equipment for low-volume work but also as a “digital combatant” against presses of that type for short-run packaging.
Penge, likewise, reports that Heidelberg’s B2 (20x29˝) Speedmaster XL 75 with the Anicolor keyless inking system has been finding its way into packaging environments. Schardt comments that “for the more intimate brands and those with versioning or market-specific content, short runs will likely continue to grow, and costing will favor the smaller format press.”
A Word on Web
Package printing, of course, doesn’t belong exclusively to sheetfed lithography: high-capacity web offset presses contribute significantly to total output in both folding carton and flexible film applications.
Chris Brooks, manager, packaging sales Americas, Goss International, notes that although web production needs more volume to reach peak cost efficiency than sheetfed printing, it can outdo sheetfed for economy in jobs that combine large volumes with heavy versioning.
Web offset, with its comparatively low plate cost, is also a better bet than flexo or gravure for shorter runs because of the high plate and cylinder prep charges associated with those processes, according to Brooks.
Goss’s principal offset product for the folding carton market is the Sunday VPak 500 press, featuring a 33.5˝ web width and quick-change plate cylinder sleeves for infinitely variable cutoffs.
Digital Seeks Its Share
Despite its many strengths, offset’s position in packaging isn’t unassailable.
Digital presses for label and packaging applications have entered the market, and printers are looking seriously at them. Alert to the opportunity, Heidelberg, Koenig & Bauer, and Komori have introduced their own digital presses for folding carton production.
However, no one is suggesting that offset will cede serious ground to digital anytime soon. Dan Maurer, Heidelberg’s VP for digital print, observes that while some digital presses now can print “just like offset” in terms of format size, stock range, color accuracy and consistent print quality, mainstream offset work isn’t necessarily what they’re good at.
“It is better to think of digital presses for folding carton and other packaging applications, as complementing offset and growing markets for brand managers,” he says. “Variable data is unique to digital presses and the leaders are exploring the benefits of full variable content for test marketing and sales promotions.”
Toss-Up Taste Test?
Digital’s “sweet spot” of unit cost advantage still exists, but it may be getting harder to taste. Penge says that because late-model offset equipment has pushed so far down into the lower limits of run length economy, printing 1,000 sheets on a digital device probably won’t yield all that much of a savings over producing the same job on a fast-makeready, low-waste offset press.
Manley has compared the monthly acquisition and operating costs of a digital packaging press with those of an offset packaging press from RMGT, assuming that each is running at 80% of its maximum productivity per shift. He says his analysis reveals a monthly throughput advantage of 450% for the offset press — and a cost per sheet advantage of nearly 600%
If numbers like these are reliable, there seems to be no reason to question Penge’s prediction that offset will go on reigning “for decades” in the volumes and applications on which its reputation rests.
The offset press manufacturers are taking nothing for granted, however. Chmura notes that declines in industry profit margins coupled with increases in the cost of capital aren’t making it easy for printers to invest in the production equipment they need in order to remain competitive.
But, he has faith in their faith in sheetfed offset, the process he says “out-produces deliverables every minute of the day.”
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