PFFC - April 2008 - (Page 14)

WEB LINES Your Guide to the Right Web Guide W By Timothy J. Walker Contributing Editor ebs are blind—they don’t know unwinding and displacement guides are nearly where they are going. With a wellfoolproof options. Once set up properly, it is easy aligned roller, sufficient tension, to forget these guides are even there because they and good traction, the web has usually perform their function without fail. a tendency to track down the centerline of a An unwind sidelay guide has the simplest web path machine. However, web and machine are not but requires a larger actuator to move the unwind perfect and many processes occasionally lose and unwinder. A displacement guide immediately tension or traction, so centerline tracking can’t downstream of the unwind adds slightly to the be assumed. Enter the automatic web guide, the web path but guides with a smaller actuator and seeing-eye dog of the converting industry. without shifting the unwinding roll or unwinder. All converting processes have some left-right For intermediate guiding, the first choice is a tolerance of web position. The first goal in web displacement guide. guiding is to get the unwinding roll aligned to Steering guides should be reserved for one the roller or centerline application: to guide a of the machine. This long span, such as the web usually can be done exiting an oven. Steering Steering guides, by far, manually by eyeballing guides are a tempting where the unwinding choice, since their design are roll is placed on the appears to take up less unwind chuck or shaft. space than a displacement of many more guiding After hitting the first guide, requiring only one roller, the left-right moving roller. But don’t headaches than the tolerance of web position do it. Steering guides, by may get more challenging. far, are the source of many other options. Does the web align to more guiding headaches the coating head? To than the other options. trim knives? To the Steering guides with laminator? To the winder core? To the other layers short entry spans are wrinkle generators. Steering in a winding roll? If you worry about your blind guides need to be designed carefully for the and imperfect web going astray, select an automatic correct spans, wrap angles, traction, and pivot guide to meet your needs. radius or they will fail to perform as anticipated. There are three main points where guiding is needed: For long spans, they are the best. If you have a 1. at unwinding; short span, consider yourself warned. 2. at an intermediate point in your process; For winder guiding, choose either a 3. at winding. displacement guide immediately upstream of the There are four options for automatic web guides: winder or sidelay. A winder sidelay guide isn’t A. unwind sidelay; really a web guide but a web chaser or winder B. displacement; guide, placing your winder in front of the web C. steering; wherever it may wander, much like a baseball D. rewind sidelay. catcher chases wild pitches. For each guiding need, there are at least two The best winder guiding is a sixth option: good options to meet your needs. For slitting. No automatic web guide will ever unwind guiding, first consider E, none beat the exactness of the web’s edge of the above. position immediately after slitting. If your input roll alignment is When the side of a wound roll good and you manually align to a looks like a phonograph record, it centerline reference mark, there is no is almost certainly from winding need for an automatic unwind guide. immediately after slitting. THE RECIPE FOR However, if you have telescoped The right automatic guide SCRATCHING input rolls or want to start your installed properly is a wonderful process with accurate lateral position, thing. It is a tireless, faithful, often choose either A or B. Both sidelay forgotten key to your operation. the source COMING NEXT MONTH Web handling expert Tim Walker, president of TJWalker+Assoc., has 20+ years of experience in web processes, education, development, and production problem solving. Contact him at 651-686-5400; tjwalker@tjwa.com; www.webhandling.com. 14 | APRIL 2008 WWW.PFFC-ONLINE.COM http://www.webhandling.com http://WWW.PFFC-ONLINE.COM

Table of Contents Feed for the Digital Edition of PFFC - April 2008

PFFC - April 2008 Table of Contents First Glance Calendar of Events From the Editor Web Lines Process Management News Clips Narrow Web & Label Reporter Narrow Web & Label What’s New Products Carton & Box Reporter Carton & Box What’s New Products Green Converting Pouchmaking Show Preview Flexible Packaging Gravure Printing What's New Products Services Directory Classifieds Marketplace Equipment Buyers & Sellers Advertisers Index Experience Speaks

PFFC - April 2008

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