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Oct 1, 1995 12:00 AM
As the press becomes just one module in print production, controls gain importance
It's not the printing units, it's the controls that make the difference!
What's more, controls are becoming part of a more sophisticated, far-reaching printing production electronic highway, tying together the elements of a plant to create a quick response, flexible, digitally integrated manufacturing operation.
All manufacturers make presses that fundamentally produce printed products with little differentiation. All manufacturers offer enhanced make ready features. Automatic or semi-automatic platechanging systems are becoming standard. Within a given class, press speeds are approximately the same. Therefore, from an equipment perspective, the differentiation among printing presses is the controls.
Press controls have evolved from on/off switches, hand wheels, knobs and levers, to consoles equipped with microprocessors, built-in computers, display screens and fiber optic links. Closed-loop controls supplement (and in some cases replace) the lead press operator's educated eye.
At DRUPA earlier this year, it became evident that the press is becoming only one module in a printing production chain with many control parameters being set outside of the pressroom - often in prepress operations. In the future, at least some preset and control functions also will be input by the customer!
The trend is for both sheet-fed and web offset production to replace human judgement and manual instructions with science, electronics and digital information.
In the current and future competitive environment for print, the formula for profitable survival is a mix of cost reductions, improved quality, shortened production cycles and value-added customer benefits. Automation on and around the press, closed-loop controls and the implementation of data-centered integrated manufacturing techniques are the tools that can provide both productivity improvements and unique, demanding customer benefits.
A current ad from Komori drives home the customer satisfaction potential of automation and controls: "Customer's got one hour for approval and we've got to produce three different jobs on three different sheet sizes with three different calipers. How do we do it?" Komori rhetorically asks.
"With the push of one button and in less than two minutes the console provides automatic presets for brush rack wheel assembly, feedboard, side guides, impression cylinders, slow down wheels and side joggers. The Print Quality Console provides automatic ink/water balance and with accurate automatic platechanging and on-the-fly moves, register is obtained in the first pull," claims the Komori ad.
Komori's automated press functions are monitored by an integrated system that incorporates control of the automatic makeready systems, cleaning functions, automatic platechanging, troubleshooting procedures and statistical process control. Known as the KMS, the system monitors data collected from the press and peripheral devices. Displayed information enables the press operator to run based on data rather than just experience and "gut feel."
Introduced at DRUPA, Komori now offers a closed-loop scanning SpectroDensitometer that provides automatic measurement using densitometric and spectral evaluation functions, data collection and analysis. This system provides closed-loop press control as well as statistical process data reporting.
Individual press manufacturers, and a growing number of peripheral suppliers, each have their own, sometimes controversial, approaches to automating the printing press and incorporating closed-loop controls. Some argue that useful full-press closed-loop controls are beyond the current economically achievable state of the art. Some debate the virtues of the spectrophotometer versus the densitometer. The advantages and disadvantages of de-skilling press operators are discussed by both printers and manufacturers.
The increasing sophistication of press controls has made it possible to reduce crew sizes and to operate presses with less experienced and knowledgeable personnel. At DRUPA, Heidelberg-Harris demonstrated the high-speed M3000 "Sunday" press with a crew of three operators.
Some look to the day when a single technician can operate a large quick changeover web press. Some experts also look to the day when the press technician is replaced by a machine tender who supervises more than one press.
Nevertheless, not everyone agrees that the highly knowledgeable and experienced press operator can be taken out of the operation equation.
Phil Tobias, founder and president of Tobias Associates, advises printers to "close the loop with the press operator still in the loop.
"An automatic closed-loop system, whether on- or off-line, must cope with a fairly knotty set of problems. It is difficult to solve these problems with a closed-loop system that is as good or better and faster than a press operator.
"When the dynamics of press inking are completely understood and controlled, then automatic in-line or off-line closed-loop systems might be worth the cost of their implementation," Tobias asserts. "Until then, we don't think that automatic closed-loop color control is a viable alternative to keeping the press operator in the loop."
Tobias does advocate the use of data, and the company's scanning densitometer system incorporates a PC to provide the press operator with densitometric information displayed on a monitor or printed with out-of-tolerance conditions automatically flagged. The accompanying SPC program enables printers to determine the relative performances of equipment, supplies, personnel and the nature of a job over the length of a press run.
Pointing out that ink control alone does not constitute press control, Iain Trevor Pike, product manager of densitometer manufacturer X-Rite, notes that any closed-loop color control system needs to be a partnership between the press operator and the measurement system - a blend of craft and technology.
"There are too many interacting variables that affect color on a lithographic press to risk assigning automatic closed-loop control to any one element without concern for all the others. Such an assessment requires skill, expertise and human judgement. Instrumentation, such as our X-Scan, introduces technology into the craft of color control. In effect, it allows the operator to close the loop," Pike claims.
X-Rite's Auto-Tracking spectrophotometers are designed to provide off-line closed-loop control over difficult non-process ink color jobs, including pastels, reflex blue, dark reds and corporate logos. Designed as an off-line, but closed-loop, high-speed scanning instrument, the scanning spectrophotometer displays CIE spectral data and density measurements for automatic press control and quality assurance reporting. X-Rite equipment is used in the Komori closed-loop system.
"One of the advantages of closed-loop spectrophotometric color control is the capability to go beyond traditional press fingerprinting. With spectral data, a color management profile of a printing press can be developed from averaged run data. This profile then can be utilized in future desktop-based prepress production - not only to preview color results, but also as a digital filter upon file output," Pike explains.
Graphics Microsystems, Inc. (GMI) is a believer in the viability of closed-loop systems and offers this control approach for both sheet-fed and web offset presses. The sheet-fed system, Autocolor, is an off-line measurement system. During the press run, sheets are pulled in a systematic way and read anywhere in the printed image area, as well as on color bars, using a scanning densitometer. The data is analyzed, and color correction information is sent to the press ink control system.
The GMI on-press web system, ColorQuick, continuously measures, analyzes and implements color corrections via the press ink control system. Color measurement for the on-web system uses a holographic grading sensor to read a unique GMI color bar with built-in recognition features. Proprietary high-speed pattern recognition hardware and firmware are used to locate and verify the color measurement location before accepting the measurement as valid for color control.
A press-side ColorQuick monitor displays density differences by color and by ink key in a real-time measurement versus the job okay or target values. The monitor is constantly updated with density, midtone, dot gain or print contrast data shown as bar graphics, numerical differences and trend charts.
Graphics Microsystems also has introduced its digital pre-setting system (DPS). DPS takes full-page PostScript data, converts it to recommended ink key settings for press start-up and sends it to a GMI server in the pressroom. When needed, the preset values are called up by the Microcolor ink control console and automatically adjusted for the printing characteristics of the specific press by AutoScanCal software.
Dynacolor from Perretta Graphics is its closed-loop color control system. It uses an on-press density scanner to obtain ink density data by scanning a color bar target on a moving web. In fully automatic mode, the system reads density values, displays them, and adjusts ink fountain keys automatically. The semi-automatic mode permits press operator intervention for ink adjustment.
Press peripherals supplier Baldwin Graphic Systems is developing a line of "smart control technology" products designed to bring the control of auxiliary equipment into seamless mechanical, electrical and electronic integration with the press system. By using a touch screen, the press operator will have a single "touch and run control" station for multiple auxiliaries.
Under the overall label of Vision-Press Specific (PS), the system ties together automatic cleaning systems, ink handling and consumption equipment, fountain solution management equipment, print temperature management systems and infrared/ultraviolet drying and curing systems.
The Baldwin approach includes several modules, some introduced at DRUPA, some still under development.
Quad/Tech has developed a variety of peripheral and printing press control equipment. Products include an automatic closed-loop color-to-color register control system; a preset control system for web press angle bars and compensators for folder and in-line finishing applications; a product tracking system that detects web imperfections and pinpoints where defective product starts and stops; and a new approach to web break detection in the heatset dryer.
At DRUPA, Quad/Tech introduced a color measurement system (CMS) concept that takes the subjective elements out of how color is perceived. According to the manufacturer, on-line measurements will assign numerical values to the densities of color. These values will be conveyed to press operators to help them make more accurate quality and productivity decisions.
One of the most complete and sophisticated press control systems is the Printa Total Control System from Honeywell's Graphic Industry Automation Center. The system, designed for newspaper and commercial web presses, provides a series of tools for managing all of the controls. Included are auxiliary devices for a single press, a group of presses or an entire printing plant, all controlled from a single workstation.
Functions controlled by the Printa can include pre-press, web control, inking, register, closed-loop color, dampening, dryer, chili stand, folder, finishing equipment and diagnostics.
Various system modules collect, process and display information for press operators, execute closed-loop control, record processes in SPC formats and report information reflecting press and/or plant operations. The Printa system integrates control and data functions.
Like the instrument and peripheral device suppliers, the press manufacturers offer their new press customers a variety of modulized control and press automation devices. Press manufacturers, however, are taking the lead in developing the framework for multiple devices handling everything from prepress to postpress data and integrated control systems. With the possible exception of Honeywell's Printa system, the press manufacturers are unique in their broad attempt to encompass production and process control in a single network-linked system.
At DRUPA, Heidelberg, for example, introduced the expanded and updated version of its digital press control system. Known as Data Control, it links the print production process from prepress to press and the bindery. To make this system workable with a mixed array of machinery from several manufacturers, Heidelberg has joined with other industry vendors to create standards and common protocols that use Adobe's PostScript to describe data. The development group, known as CIP3 (Cooperation for Integration of Pre-press, Press and Postpress), will make its machine interface, PPF (Print Production Format), available to all equipment manufacturers.
Heidelberg is bringing this concept to market as the Data Control CPC 51 and the CPC 32 prepress interface. These modules are part of the CP-Tronic and CPC control system, which also includes a remote control system, quality assurance system, in-line image measurement and an auto-register system - all of which Heidelberg says are undergoing continuous but compatible improvements.
The Data Control system creates links between the administrative production control and production operating functions of a print shop. This enables all presses equipped with a CPTronic to be fed with order data such as run length, sheet format and ink settings.
Data also flows in the other direction - from production operations to management to provide an overview of the current status of individual orders and scheduling. Data is provided in real-time, which increases capacity utilization and flexibility to react to required changes.
Running virtually parallel to the CIP3 standards and common protocol development is a U.S. effort called Press-Script, underway at the Rochester (NY) Institute of Technology Research Corp. The primary conceptual difference between the two approaches is that CIP3 uses PostScript and the RIT effort is an SGML-document-type definition. RIT Professor Frank Cost explains that SGML is a context-free language.
The PressScript approach, using SGML, makes it possible to describe relevant characteristics of a printing form that are useful to press equipment, density measurement instrumentation, color measurement instrumentation, visual evaluation and finishing equipment.
MAN Roland's Process Electronic Control Organization and Management (PECOM) system is the link that tied its DRUPA sheet-fed and web presses into a digitally linked pressroom, controlled from a single remote workstation.
PECOM is a three-tiered system that integrates electronic job jackets, press and printing characteristics, and press control functions for both sheet-fed and web presses. Dual fiber optic lines connect the PECOM's CPU to individual CPU's in each press unit, permitting two-way data transmission in a closed-loop environment.
The networked printing plant was illustrated at DRUPA by KBA. Using its OPen ERgonomic Automation system (OPERA), the company showed how different press types can be linked with each other as well as with central systems for press presetting, quality assurance and production management systems.
The OPERA control center is a new KBA console designed for fast reacting console-to-press communications in a real-time mode.
Basic system modules include (1) Colortronic, a control desk for remote ink key adjustment; (2) Scantronic, a plate and film prescanner; (3) Densitronic, a scanning densitometer system from GMI; (4) Qualitronic, which uses an on-press CCD camera to compare each printed sheet with a press okay sheet; and (5) Logotronic, a production management system.
With press systems such as OPERA, claims Robert McKinney, vice president of KBA-Planeta marketing, digital data is readily available for printing plant logistics and production management from scheduling through production. Prepress, press and finishing operations gradually will be integrated as interfaces via networks allow access to digital data for pre-setting, control and quality optimization.
Mitsubishi's Diamond Link press control system includes a personal computer in the main console. This computer controls the functions of the entire press, including ink presetting from plate scanner data; initial settings for ink rollers, dampener rollers and web widths; and production control information downloaded from a printer's management information system.
In addition to press functions, the Diamond Link system can communicate with and provide control information to auxiliary equipment, including dryers, splicers and color control systems that are not supplied by Mitsubishi.
Rockwell has been applying cutting edge electronic and control technology on both its newspaper and commercial web systems since the early 1970s. Yesterday's breakthrough systems, initially adopted by a few pioneers, are today's "widely accepted plain vanilla systems," claims Al Sheng, Rockwell's vice president of engineering.
The next step for Rockwell is a color correction system that utilizes a video vision approach and examines the entire image rather than just color bars. The system can be used to preset press ink controls by scanning or taking a picture of a proof and reading and recording individual color or separation values. This information then is manipulated mathematically, taking into account the characteristics of a particular press in order to determine ink preset values.
During the run, Sheng explains, copies will be systematically pulled, looked at by the vision system, and the data compared to the original proof, enabling ink adjustments to be made as necessary.
Computer-to-plate (CTP) devices have potential as printing production and process control centers. The ability to use digital data to preset ink controls already has been demonstrated by Creo and put into commercial practice by Heidelberg with its DI presses. As CTP systems are further developed, the need to scan plates or film to obtain ink preset data will become technologically obsolete.
PrintCom's long-range scenarios include the continuous feeding of press fingerprint data to a CTP system. Production control data, some of which will be input by the printer's customer and some by the printer, combined with imposition, trapping and similar data will be utilized to create "job perfect" customized plates for each press.
This scenario calls for the CTP system to become a press control and, even more broadly, a printing production control center.
As you can see, it's not the printing units that will be the critical factor for success; it's the controls that will make the difference.
WILLIAM C. LAMPARTER Contributing editor and president of PrintCom Consulting, Charlotte, NC