Web guiding systems have a mission that’s simple enough: to hold a web in an exact position, preventing lateral movement as the web is processed, and when the web leaves the correct position, the sensor signals the guide structure to laterally move the web back to the proper place in the sensor’s field of detection.
Over the years, converters have gone from mechanical solutions-that is, methods that use sensors that physically contact the substrate-to non-mechanical systems, a transition that has led to developments benefitting production by upping efficiencies and maximizing profits.
Digital sensors keep an eye on the webAs more and more components of a converter’s line go digital, so, too, do the “eyes” on your web. One of the most recent examples of this type, Fife’s new SE-46 line guide sensor, eliminated the need for a “striker line” (and inherent waste) and looks to existing one-dimensional graphics, like bar codes or printed borders, to guide a web.
“Many of our customers have a need to reduce operating costs wherever possible, without compromising accuracy,” says Ron Suenram, product manager for Fife. “This new sensor gives them the ability to guide to existing elements and achieve higher press speeds.”
Requirements for these existing printed elements are minimal: The sensor can “see” lines as narrow as 0.02 inches. What’s more, the clearance between printed elements required by the SE-46 is reduced to 0.008 inches, further expanding the range of potential printed elements used to track a web.
The guiding light: an LED?Several types of sensors, including those using cameras, lasers, infrared or ultrasonic technology, work well and have proven more dependable and accurate than their mechanical predecessors. BST Promark, a leader in video inspection and web guiding technology, improves on this reliability and precision with its CLS Pro 600 line guiding system.
“This unique guiding device uses automatic LED lighting and a color CCD camera that provides laser-guided precision and unparalleled ease of use,” says John Thome, general manager at BST Promark.
The CLS Pro 600’s color camera precisely scans web edges or printed elements, like lines or print edges, and offers users the ability to shift the reference position in the range of a few millimeters for maximum precision. Thome explains that the compact unit is complemented by a high-resolution color display featuring screen navigation with simple icon controls that lead to a whole new level of intuitive operation.
AccuWeb of Madison, Wis., uses three LED light sources with three independent light source positions in its AccuBeam 3 digital color line guide sensor. The LED sources have an expected lifetime of 100,000 working hours and emit three colors-red, green and blue. Each color of light produces one optimum contrast for the 128-pixel CMOS to work with, which improves accuracy and ultimately your production.
The answer's blowing in the wind
“The system operates on low pressure plant air, about 3 to 6 pounds per square inch. So there’s no need for any wiring or electrical components,” continues Marks. “You simply bolt the guide into position and connect to plant air.” Besides sipping only a small amount of energy, Marks also indicates that an all-air system is beneficial when installing your guiding equipment near a corona treater, electron beam oven or interference-sensitive equipment.
Web guide sensors come in a variety of flavors, but no matter what type you do use, letting the right sensor keep an eye on your web is as important as keeping an your eye on your bottom line.
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