Web-Guided Tour

A web guide technology overview confirms the progression of electronic controls, automation and custom approaches.

By Susan Friedman

Hardly an unfamiliar concept, web guides are often a taken-for-granted component of presses and converting lines. A closer look at this technology's latest developments can help converters squeeze further efficiencies from even the most intricately tailored press configurations.

Web guides' longevity hasn't completely wiped out usage misconceptions. When Allen Rausch, application engineering manager for BST Pro Mark, Elmhurst, IL, is in the field, he often sees guide sensors positioned too far within the exit span of the guide frame. To work best, sensors should be in the first third of the exit span, he explains.

In addition, choosing among pneumatic, hydraulic or electronic web guide controls may not be as clearcut as prevailing wisdom suggests. "There's a common belief that you can't use electronic web guides in explosive or hazardous environments, but many of them feature explosion-proof motors and intrinsically safe barriers, or limited energy circuits, that prevent sparks," says Joe Klimczak, project engineer at AccuWeb, Madison, WI. He adds there is a misconception that hydraulic or pneumatic guides are the least expensive control options, when they may harbor high installation costs.

The current web guide marketplace necessitates both competitive purchase prices and efficiency returns. Klimczak likens the guide industry to the computer market, stating, "As technology increases, prices decrease." Waste and downtime reductions are specific to the application, "but plant managers won't spec a guide system unless ROI is less than a year."

Application windows

Pneumatic, hydraulic and electronic guides all have solid application windows, though electronic guides appear to be a frequent conversion choice. "For narrow-web, high-speed applications, electronic guides offer the cleanest power source and are probably the most efficient," comments Steve Tannenbaum, president of Hydralign, Avon, MA.

Donald Ross, VP sales at Erhardt+Leimer, Spartanburg, SC, observes a gradual change from hydraulics to electronics due to hydraulics' continually running motor requires more maintenance, and the systems' leakage tendencies can be problematic for food packages or environments that need to stay clean. He believes pneumatic guides have taken over a lower-cost niche, and offer proven advantages in explosive environments.

Though he affirms the movement toward electro-mechanical guides, Eddie Engledow,product manager at Fife Corp., points out that a hydraulic guide's ability to provide enormous amounts of thrust may make it the best solution in large applications, such as a 50,000 lb. unwind station.

Bob Duffy, marketing coordinator for Coast Controls, Sarasota, FL, notes electro-mechanical systems may not fare too well in dusty environments. Duffy cites the case of a chewing gum manufacturer that uses powdered sugar to lubricate the gum on their web-fed packaging lines. The previously installed electronic sensors would become covered in sugar and require considerable downtime to be manually cleaned. Coast's air-controlled displacement guides eliminated this problem, expelling air through air-flow sensors that didn't permit the sugar to settle and disrupt sensing.

A standard-custom split

Fife's Engledow characterizes today's web guide industry as split between standard and customized offerings. If a guide falls within a company's standard parameters, package printers can be assured quick delivery, he explains. On the custom side, size variations don't increase component prices as much as features like extra controls and tensions, he says. "Converters expect custom solutions at standard prices," Ross states, relating that Erhardt+Leimer plans to achieve this by broadening its line of standard guides.

Accuweb's Klimczak adds, "CAD designs allow stretching or shrinking of standard designs to meet customer needs and lower engineering costs." It may seem obvious, but experts repeatedly underscore the importance of clear printer-supplier communication in arriving at the most cost-effective guide solution, particularly when a nontraditional product is sought. Coast's Duffy recommends submitting a side-view diagram of how a press is threaded, to ensure that guides will fit right in with the press frame.

Presses that are short on space and long on function present a common custom guide challenge. Engledow states space constraints require nearly endless versatility, particularly with mounting of guides. As press lines get longer to accomplish more processes, printers need to add guides, he notes, creating a greater squeeze on space.

And, with more guides come more control upgrades. Tannenbaum cites a trend toward simplifying electronics by controlling more web guide configurations from a central location, instead of with multiple stations along the lines. Suppliers are also geared to handle a range of web widths, or to zero in on a specific size parameter. "Many presses are designed to run widely varying web widths, so it's important to choose a guide that can accommodate the maximum width desired," comments Duffy. "The sensors can always be moved in for narrower webs." BST Pro Mark, on the other hand, is introducing sensors, actuators and frames designed for narrow-web needs.

Shel Silver, customer engineering manager at Martin Automatic, Rockford, IL recommends smaller cantilever mounted guides, which have a frame on only one side, for convenient control and maintenance on narrow webs. To handle the substantial tension loads of wider webs (on standard full-frame units), a second motor may be necessary on a guide, but a similar amplifier can be used for narrow- and wide-web control.

Substrate complexities, too, can negate a one-size-fits-all attitude toward web guides. "More complex substrates entail a greater variety of sensing systems," explains Tannenbaum. "Some electronic sensors can't detect clear plastic webs because the light will shine right through them, while some materials may absorb ultrasonic sound waves."

Ross is seeing requirements to provide split web guides that allow printers to run two jobs on a common single-faced web. For multi-wall bag makers, Duffy says Coast provides vertical mounting stacks consisting of up to six independent all-air control systems and intermediate steering guides for aligning each ply in the bag process.

Rising IQs

As approaches to customization are fine-tuned, web guides themselves are getting smarter. Rausch contends that fully automated installations are on the rise, such as BST Pro Mark's modular EKR-1000, which uses motorized sensors to automatically handle varying web widths and substrates.

Other examples include AccuWeb's Micro 1000 ultrasonic edge detection system, which dynamically calibrates, compensating for temperature, humidity, dust and other contaminants, and Erhardt+Leimer's FE 5001 intelligent line sensor, which aligns the web by learning the width and color of a printed line. Additionally, Hydralign's Edgemaster 2000 web guide features a unique optical sensor capable of detecting virtually any material.