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ON-PRESS IMAGING -- Firing on All Cylinders

April 2002

Taking steps out of a process has the potential to increase productivity, reduce process variability and lower production costs. That all sounds great, but these gains naturally must be weighed against the investment required to achieve them.

Doing such a cost/benefit analysis for the on-press imaging concept might at first seem to be a rather straightforward calculation.

The potential variables in the equation quickly prove otherwise, however. Issues related to integration with existing plant capabilities, markets served, type of press being considered, etc., can tip the balance in favor or against the technology and workflow. What makes sense for one operation may be a non-starter in a different shop.

Technological factors are only part of the reason why the first implementations of on-press imaging were on smaller-format machines. The value proposition of the concept has always centered around quick turnaround of shorter runs, which fits well with the capabilities of smaller presses. These entry-level presses also were well suited for prepress operations and quick printers adding their first real four-color presses, which became the primary target market.

Since computer-to-plate adoption for the most part started at the high end, this meant the first direct-to-press solutions were primarily being compared to film-based workflows. The associated labor savings and process efficiencies, combined with the lack of an existing printing infrastructure at most early adopters, made it easier to make a case for the technology.

With on-press imaging solutions now moving up in format and computer-to-plate (CTP) systems expanding down, the two workflows are becoming more directly competitive.

On-press vs. CTP Debate

As a result, perhaps the biggest question potential buyers now face is: Why spend the money to put imaging systems on every press unit, when a complete set of plates can be made in a single off-line CTP system that has a much lower capital cost? Most of the same benefits claimed by direct-to-press systems can also be achieved by adopting off-line CTP production, especially if the comparison is made to an automated platesetter and state-of-the-art press.

As manufacturers of standalone CTP systems and on-press imaging kits, Creo Inc. and Presstek Inc. are in a unique position to evaluate the relative merits of the two technologies. If anything, one might expect the manufacturers to be biased in favor of CTP machines, since they sell those devices, but do not market complete digital presses. However, the market experts at both firms believe a strong case can be made for on-press imaging, both in terms of cost/process advantages and marketing potential.

First, a couple points of clarification probably are needed to put their comparisons in context. Since Presstek holds a registered trademark on the "DI" (for digital imaging) designation, Creo has adopted the DOP (digital offset printing) acronym for its technology. In broad terms, both designations refer to the same class of products.

On-Press Imaging Solutions
 Imaging systemNo. of colorsMax. Sheet sizeMax. Speed (iph)Comments
Two-page Sheetfed
QM DI 46-4
Presstek413-3⁄8 x 18-1⁄8"10,000waterless
Ryobi 3404DIPresstek413.39 x 18.11"7,000waterless
Screen TruePress 544Screen 415.5 x 21.4"3,200conventional
Xerox Docu- Color 233 DIPresstek413.39 x 18.11"7,000waterless (Ryobi)
Four-page Sheeted
Adast 705C DIPresstek4, 519-1⁄16 x 26"10,000waterless
Heidelberg Speedmaster 74 DICreo4-620-7⁄8 x 29-1⁄8"15,000conventional
74 Karat
Creo420.5 x 29.1"10,000waterless
Sakurai Oliver 474EPII DIPresstek4, 521-1⁄16 x 29-1⁄8"13,000conventional
Xerox Docu- Color 400 DIPresstek4, 515 x 20.5˝12,000waterless (Adast)
Eight-page Sheetfed
Project D
Creo4-828-3⁄8 x 40-9⁄16"16,000conventional
MAN Roland DICOwebCreo611.8 - 20.5" *20,000conventional
(*web width)

The range, number and size of the products in the on-press imaging category continue to grow, as the product chart on page 30 shows. This makes it somewhat risky to make blanket statements about the technology, since some may not apply equally to all systems. Hopefully, the product-specific exceptions will be self-evident.

The key advantage of DOP presses is their potential to support shorter cycle times, contends Brad Palmer, corporate vice president of on-press technologies at Creo, based in Vancouver. "This enables the printer to be more responsive to customers and charge more for a higher level of service," he explains.

On-press imaging also lowers the production costs for shorter runs by eliminating platemaking operations, Palmer says. This process simplification, combined with the press operational streamlining possible in an all-in-one unit, makes it easier to manage production and respond to job changes, he continues. The net result is faster makereadies, which means the press can be kept running more of the time when producing short-run jobs.

Creo recently issued a revised white paper that makes the business case for digital offset printing. It includes a DOP vs. CTP cost comparison for a sample job, which shows the former achieving up to double-digit per-copy cost savings for runs of less than 2,000 impressions and maintaining at least a couple percent cost advantage for run lengths to 12,000 impressions.

The example in the white paper is based on a four-over-four-color, one-page job printed four-up on a modern five-color press. According to Palmer, the analysis assumes the same processless plates are used in both workflows and the presses have similar automation features. All costs are factored in, he notes, including equipment amortization, labor, space overhead, insurance, service contracts, etc.

A significant part of the savings from DOP production is the result of eliminating the labor involved in off-line CTP platesetting, Palmer says. It's worth bearing in mind that this analysis is based on a manual CTP system, but an automated machine would increase the associated capital costs.

The other part of the savings is the result of a quicker makeready compared to CTP-based production, he adds. "The on-press imaging operation is integrated into the makeready cycle and it doesn't extend that time any. The savings result from the digitally perfect registration you get with the DOP press, which means you achieve register and color in fewer sheets, saving time and material costs."

Palmer concedes that the payback model is very sensitive to the particulars of a print shop and how it is operated. For that reason, he believes DOP and CTP will co-exist in the market over the long term and, in some cases, co-exist in the same shops. "They serve different niches of the market and offer different economies," he asserts.

Format for Success

Stan Najmr, director of DI marketing at Presstek, in Hudson, NH, comes at the question from a slightly different perspective, but offers a similar assessment that DI's advantages stem from its streamlining of the process.

"DI systems offer all the benefits of CTP, plus fully automated, in-register printing with extremely short makeready times," Najmr asserts. "All of this process automation provides users with a short learning curve and fast entry into the high-quality, on-demand, four-color printing market."

It's a mistake to view a direct imaging press as just an existing press to which laser imaging kits have been added, Najmr says. "Printers have to evaluate the productivity of the complete system compared to a conventional workflow. In order to get maximum benefit from a direct imaging press, you have to integrate four main components: spooled digital imaging media, laser imaging heads, a unique press design (V-shape cylinder configuration) and the digital front end."

Since the typical DI press uses spooled media that is fed automatic-ally and can image all colors at once in about three minutes, there's no way plates can be produced off-line and then hung on a press in a similar time frame, Najmr points out.

In most of the cases, the entire digital imaging kit for a press—lasers, digital controls and cleaning systems—costs less than a comparable CTP device, adds the marketing director. The resulting cost structure for short-run production, combined with the marketing potential of quick turnaround, results in higher margins, he says.

Even given these advantages, Najmr asks, what if a printer already has a conventional press and can't afford to obsolete it? "In the short-term, CTP systems will be successful for that reason," he says. "However, over the next five to 10 years, DI presses—complemented by toner-based digital printers—will become the industry standard. It just makes economic sense."

There are other issues that can factor into the on-press imaging buying decision, beyond those directly associated with costs. Most are of greater potential concern to shops already running conventional color sheetfed presses.

* What happens if an imaging unit goes down? The manufacturers point out that the duty cycle for an on-press imaging system, over a set time period, is significantly less than that of a CTP system used at anywhere near its capacity. This is because the on-press system is idle during the press run. Therefore, the life expectancy of the laser should be increased, they assert.

With some of the presses, a plate still can be made in a separate operation and installed on the printing unit in the traditional way.

* One cost associated with all types of digital imaging that can get overlooked is the often sizable service contract that generally comes with a purchase. Buyers of pressroom equipment may not be accustomed to dealing with such charges, which are now associated with DI/DOP presses to cover maintenance of the imaging systems.

* While several of the more recent digital press introductions use a conventional offset printing process, the majority of the systems run waterless. If a printer's current operations are all conventional offset, management may be hesitant to introduce this new variable into the plant.

In the final analysis, the on-press imaging value proposition may come down to how much is time worth? The capability's sweet spot is quick turnaround (often the same day) of short runs (1,000 impressions is a good average). These parameters make it hard for any other workflow to be competitive. There's little opportunity to make plates ahead of time, and a single CTP system typically can't make a full set of plates in the time it takes to complete such short runs.

The big question: How does that business model fit with a potential buyer's operations and customer base? Ultimately, the suitability of on-press imaging can only be determined on a case-by-case basis.


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