Quality Printing--Handling it Right

Proper web guiding, tension, and register control are basic ingredients needed for good print quality results.

PRINT REGISTRATION IS one of the first things packagePRINTING's Excellence Awards judges inspect when assessing the print quality of contest entries. For our expert panel, it's an easy variable to assess, and is used as an initial culling point to "separate the men from the boys." Entries will not contend for a first-place finish if they are not produced with good print registration.

This is clearly understood in the industry, but not everyone pays enough attention to some of the web-handling issues that directly impact registration, says Henry Rissier, president of AccuWeb (Madison, Wis.). "Poor registration is one of the most common print defects, and while many companies spend thousands of dollars on register control equipment, few address the root cause, which is often related to web control," he states. "Precise web guiding is a critical, but frequently overlooked requirement to producing superior print graphics."

There are innumerable variables that impact the ability to precisely control a web in its journey through a printing press. Many of these variables are directly related to the materials themselves.

"Webs can vary from vendor to vendor, roll to roll, and even within a roll," observes Jim Ward, VP of engineering for Martin Automatic (Rockford, Ill.). "The single most important step that one can take to fixing web problems is to avoid them in the first place. Choosing the right material supplier can have as much impact on a successful operation as choosing the right machine."

Bob Sarnelli, web tension product manager for ABB (Brewster, N.Y.), points out another big issue for package printers—the need to handle a wider variety of materials with the same machinery, from heavy to very thin and wide to narrow. This needs to be done while "still having perfect control over the process," he says. "Both the tension measurement systems and the newest digital drives need to have the widest operating ranges to meet the demands."

Ward offers another necessary ingredient for running a wide range of materials. "It has been my experience that those converters who are most successful in these efforts have engineering and production staffs that have a good understanding of web handling, machine design, and process controls. Without these tools, converters will continually be dealing with basic web-handling issues or spending considerable time and resources on areas that have little return on investment."

So, the solution to these increasing web-handling challenges is the same as any other problem in manufacturing—a package printer must run top-notch materials, on top-notch equipment, with top-notch operators and support personnel. Suppliers of web-guiding systems are doing their part in this equation by building flexibility, reliability, and simplicity into the components and systems they offer.

Web guiding

Fife Corporation (Oklahoma City, Okla.) is listening and responding to its customers' need for simplicity. "Our customers have pushed for innovating new ways to improve accuracy, quality, and support," says Ron Suenram, product manager for Fife. "This time, our converting customers added simplicity as their biggest requirement. The converting industry is always changing—with more operators responsible for setup and operation of a single web-guiding process, the need for simplicity has really become an issue."

Fife's new POLARIS web-guide controller is designed to reduce the time and effort required for setup and operation. Instead of operators needing to learn special codes and characters to set up web guides, POLARIS provides them with a digital display capable of full line text and simplified key commands for setup and operation.

Dave Rumage, district manager for Fife, adds that POLARIS allows the use of all of the company's different sensing options, such as ultrasonics for clear films and infrared for opaque materials.

Simplicity is the selling point for web-guides supplied by Coast Controls (Sarasota, Fla.). It manufactures guiding systems that operate entirely on plant air. "With so much emphasis being placed on digital technology, Coast Controls continues to take a different approach to web guiding—one that operates entirely on low-pressure plant air," says Bob Duffy, chief operating officer. "Our all-air guiding system—featuring both air-controlled sensors and actuators—has two fundamental advantages over other guiding systems—simplicity and dependability."

Converter Accessory Corporation (CAC, Wind Gap, Pa.) uses an all-electric approach with its heavy-duty Pivotrac® HD system. It's positioned as an accurate, low-maintenance system that can be used on most machines, including slitters and printing presses, to provide edge accuracy of ±0.005˝. According to Pam McCauley, general manager for CAC, Pivotrac web-guiding systems can provide the enhanced production and versatility needed by converters to be successful in the current demanding market environment.

A digital approach to web guiding is provided by Erhardt + Leimer (Duncan, S.C.). Its DRS digital web-guide systems have a user-friendly digital controller integrated into the unit's pivoting frame. The DRS can be used with either infrared or ultrasonic edge sensors.

To enhance the accuracy, reliability, and versatility of its web guides, Rissier points to advances made by AccuWeb in the area of edge detection. "Just as changes in environmental conditions can affect the control of color, they also can cause guide point drift that will influence print registration," he states. "For these reasons, AccuWeb developed 'dynamically compensated' edge detectors that automatically compensate for changes in temperature, humidity, dust, dirt, air turbulence, passline variations, and other factors."

North American Manufacturing Company (Cleveland, Ohio) is also improving the performance of its guiding systems at the component level. It has introduced the H5530 F-series of electromechanical actuators that are designed for simplicity and reliability. According to Tom Jonozzo, general manager of guiding systems, the actuators will be offered with the company's Simplex web-guiding systems, and will be an attractive enhancement for flexible packaging applications.

Tension control

The characteristics of the materials being run through a press are key variables that impact tension control. This is why it is so difficult to specify a machine to handle both ends of the materials spectrum. But this doesn't mean that converters aren't trying.

"One trend that we see is that more converters are trying to specify all-encompassing machines with a 'soup-to-nuts' spectrum of material capabilities," says Craig Thomson, Martin Automatic's marketing manager. "Obviously, the more flexible a new machine is, the more potential it has for enabling converters to go after new or more profitable business, either right away or with possible future applications in mind."

He cautions those seeking this flexibility that it may come with a price that is too steep. "The typical web-handling components that are designed for paperboard, for example, will likely not be the same as those used for very thin films. When faced with the realities of the cost of such flexibility, many customers will narrow the scope to keep down the total project cost."

To broaden the range of materials that can be run with its products, ABB has developed its newest line of web tension load cells. According to Sarnelli, typical tension systems have a 10 to 1 tension application range, but ABB's new load cell can achieve a 30 to 1 ratio.

ABB has also developed a variable frequency AC drive motor brake as an alternative to friction brakes on unwind stands. "A motor brake has a far wider operating range than a friction brake and offers far better control, especially when the substrates get thin and light weight," says Sarnelli.

CYGNUS, a new web tension control system from MAGPOWR (Fenton, Mo.), simplifies the setup process with on-screen prompts and full text displays. The system also offers multiple setups (recipes) for different materials. "This allows quick changeover without re-tuning the control for each material," says Darrell Whiteside, product manager for MAGPOWR. Additional features include weightless load cell calibration and gain compensation for added stability from full roll to core.

Register control

With web guiding and tension under control, reliable register control can take center stage. Penny Shawah, VP, strategic applications for CC1, Inc. (Manchester, N.H.), sees an ever-increasing need for reliable register control in package printing.

"Our packaging customers are facing many challenges, including use of more complex (heavier, stretchier) and expensive substrates, increasing number of printed colors, dual-side printing, tighter front-to-back registration requirements, tighter diecut registration requirements, and use of 'invisible' or barely visible inks, to name a few," she says.

To help printers in this effort, CC1 introduced the CRC-610 Automatic Register Control system that can be set up to control each type of substrate differently on any particular run. With this capability, register data can be captured by the CRC-610 and used to fingerprint press performance—per substrate as necessary—and to set up optimal control settings based on the application requirements, says Shawah.

eltromat electronics, Inc. (Chesapeake, Va.) has also designed its DGC 650 Register Control as a simple and stable system for use over a complete range of substrates. Nat Stern, CEO of eltromat, says that the system is particularly adapted for short runs, with job pre-setting for both new and repeat jobs in order to significantly reduce start-up time and waste. "In addition, the DGC 650's advanced control algorithms and the use of the unique multi-mode single-head scanner provide rapid and stable operation for all substrates without operator adjustment," states Stern.

Reducing makeready times is the main thrust behind TruColor Vision Systems' (LaGrange, Ga.) TruRegister feature, an optional upgrade to its high-end TG 4000 Series web inspection system. With this fully automatic register control feature, Jim Doerr, president and CEO of TruColor Vision, says that registration can be corrected and controlled in less than one minute.

by Tom Polischuk, editor-in-chief