Take The Right Path

Are electronics the major factor in keeping webs in line? Or are other, more conventional options the answer?

By Chris Bauer

THE WORLD HAS gone digital. That statement has been beat to death, pushed down your throat, and probably gone in one ear and out the other countless numbers of times in the past few years, especially when it comes to printing equipment. Isn't there anything left that can be done without bits, bytes, or megs? Makes you wonder how we ever got anything accomplished before the "digital revolution."

Simpler equipment designs still have a strong appeal. Many printing companies report experiencing difficulty in finding experienced personnel. And for this reason, a simple approach to web guides is often the answer. "As an alternative to complicated electronic guides, the all-air guiding system offers a simpler approach to web guiding—without sacrificing anything when it comes to accuracy," announces Bob Duffy, sales and marketing manager for Coast Controls. All-air guiding systems, he says, use only low pressure plant air for both web edge sensing and guiding actuation.

But the real benefit of an all-air system comes back to simplicity, Duffy explains. "Production and maintenance personnel appreciate the fact that all-air guiding systems are easy to hook up, virtually maintenance free, and rarely ever need adjusting after installation. In fact, they're so uncomplicated that most people understand exactly how they work in just a few minutes."

Coast's all-air guiding systems are intrinsically explosion-proof and do not require modifications or special provisions when guiding in explosive environments, Duffy adds. Worries of interference problems when installing near a corona treater, an electron beam oven, or other devices are also eliminated.

Electronic alternatives

With that said, there are other schools of thought concerning web guides. There is no denying the strong market for electronic web guiding equipment. And suppliers are lining up to provide more intricate systems to ensure substrates remain on the correct path.

"Guiding technology has changed quite dramatically over the past ten years," says John Thome, vice president of marketing for BST Pro mark. "It used to be that everyone used air-operated systems, primarily because they were the least expensive. We certainly make air sensed systems for those customers that require them."

But this is not the direction he sees the web guide market gravitating to. According to Thome, digital technology has exceeded the guiding abilities of some all-air systems. This trend will continue in the future, he adds.Thome feels many people in the printing industry have the perception all guiding devices are the same. The only truth to that, he says, is all guiding devices follow the same rules of physics. All have sensors, a control unit, and a guiding mechanism, but that really is where the similarities end.

"On the surface you see rollers, steel, and aluminum," Thome explains. "But for longevity, reliability, and system effectiveness, it is absolutely necessary to use special steel grades and roller bearings on the components. The actuator is another critical element within the guiding device, for it is the key to close tolerance guiding." Units with detailed design of the actuator components can hold tighter tolerances and will last longer than competitive systems, he notes.

Converters who are printing, slitting, or converting materials that are guided by using a printed line on the web can benefit from a feature BST Pro Mark calls the "watchdog." It is essentially a fail-safe for missing print, Thome points out. With this feature on a guiding device, when the printed line used for guiding is not there due to bad splices or missing print, an edge sensor automatically takes over momentarily, or until the line reappears, and guides the substrate. Without this feature, the web guide is lost and directs the web inaccurately to one side of the machine, producing waste.

Maintenance concerns

A well-designed, quality web guide should have zero maintenance, suppliers claim. It should be a piece of equipment you can just turn on and expect to work day after day, month after month. "Today's electro-mechanical web guides are virtually maintenance free, except for occasional cleaning of the sensor, and a check for build-up of contaminant on the surface of the rolls," says Ed Orzel, senior manager of development for the guiding systems business group at North American Manufacturing Company. "The industry continues to move toward no set-up, hands-off systems that require no repositioning of sensors for web-width changes."

According to Ray Buisker, president of AccuWeb, "Digital takes all of the adjustments right out of the equation." He reports 98 percent of applications are pre-programmed into the unit before it even leaves the factory, and often will never need to be adjusted. This mixes well with today's trends of increased press speeds, wider range of materials, and faster turnaround times, Buisker says.

All-air systems, on the other hand, have their own maintenance advantages. Coast Control's units are impervious to build-up from paper dust, lint, powders, carbon fibers, or other matter, Duffy says, due to the servo controller that allows a positive air stream to discharge from opposing orifices in the sensor. He adds the unit will continue to detect the web's edge when running dark, opaque, transparent, or reflective materials.

To meet customer requests for a complete guiding system that is ready to be shipped quickly in times of emergency or immediate need for increased capacity, Fife recently introduced three pre-packaged guiding systems. Ron Suenram, Fife's guiding product manager, says these "plug-and-play" type guiding systems are designed for quick and easy installation. Suenram feels there is a demand for integrated systems that are available as stock shelf items and can be rushed to the web press user on-demand.

At DRUPA, Fife introduced the SE-34 Lazerwide Sensor, a laser-based sensor for web operations. The product has no moving parts and is designed to replace moving sensor center guide assemblies. It is capable of operating on web widths from 1&Mac218;16&Mac253; up to 200&Mac253;.

Whether you are yearning to hold onto traditional guiding methods or itching to digitize more of your shop, remember it is important to choose a product that you can rely on to quietly guide your substrates to problem-free completion, that your employees will be comfortable using, and will blend seamlessly into your unique mix of equipment.