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Tight Side / Loose Side Webs

Sometimes the web(s) you process may have tight side / loose side condition. This condition can be a symptom of poor machine alignment or it could be a product of the web itself. One way to tell which condition exists in your process is to view several different rolls of material as they are unwound into your process.

Over several rolls is the tight side / loose side condition consistently the same, always on the same sides? If so, then roller alignment is most likely the culprit and you may need to have your rollers laser aligned and/or roller faces re-machined to fix the problem.

The other possibility is that you see the tight side / loose side condition changing. Severity of the condition may change or possibly completely go away. Sometimes the tight side / loose side may change sides on the machine. If this is the case, then your web itself is to blame for it's condition. Webs with this condition are literally longer, in the machine direction, on one side than they are on the other. If you were to take a roll of material with this condition and unwind a very long length, let's say onto a football field, it would actually form an arc, it would not be straight. For the remainder of this article I will refer to this tight side / loose side condition as "natural camber".

Webs with natural camber can cause a lot of headaches with processing them. Specifically, webs with this condition will wander from side to side in your process, they may wrinkle and controlling their tension may be difficult. When your web has this natural camber, there is no way to permanently correct the web, except for throwing it in the dumpster and starting with a new roll.

For those of us tasked with running rolls with natural camber, there are several pieces of equipment to help with the aforementioned processing challenges:

  1. Automatic web guide systems can be installed in one or several positions throughout your machine. Automatic web guide systems use sensors to detect an edge, centerline or printed line. Most systems today are all electric making them clean, efficient, and cost effective. Web guides will sense the position of your web and actuate a web "positioner" to keep your web aligned very accurately through your process run.
  2. Anti-wrinkle rollers and systems can be strategically placed to remove any incoming web wrinkles. Anti-wrinkle rollers and systems operate based on many different operating principle but all have one common goal; remove wrinkles to deliver a flat web to a process. Keep in mind anti-wrinkle devices will not remove the natural camber from your web. What they do is simply remove wrinkles prior to an operation. Anti-wrinkle rollers and systems can only remove wrinkles that are entering them. Natural camber may cause wrinkles to reappear in your process. Several anti-wrinkle rollers / systems may be required in converting process to keep webs wrinkle free. Please see past tech tips to learn more about differing anti-wrinkle technology. You can view previous tech tips by registering on CAC's website here: http://www.converteraccessory.com/register.php

    WrinkleSTOP wrap angle
  3. Skewing the unwind roll can also help correct some natural camber problems of the web where it first enters the machine. Shaft holders and safety chucks are often times available with manual skew adjustment, making this adjustment fast and easy. Making this adjustment can help with tension control of the unwind roll as the web enters your converting process.

    Safety Chuck with skew adjustment
  4. Processing rolls with built-in natural camber can be a very challenging task. Thankfully, there is a multitude of web handling solutions available to help deliver your web through your process.

Written By: Jeffrey Damour, Sales Engineer, Converter Accessory Corporation, Wind Gap, PA, Phone - 800-433-2413




**DISCLAIMER - A great deal of time has been invested in the development of our weekly tech tips. To the best of our knowledge, they are accurate. It is up to the user to verify all results.

THE AUTHOR ASSUMES NO LIABILITY CONNECTED WITH THE USE OF THIS INFORMATION OR THE RESULTS OBTAINED FROM IT.



Converter Accessory Corporation
201 Alpha Road
P.O. Box 188
Wind Gap PA 18091-0188

Phone (800) 433-2413 or (610) 863-6008
Fax (800) 709-1007 or (610) 863-7818

sales@converteraccessory.com

www.converteraccessory.com


      
What is Web Handling?
Web Handling is the science, engineering and equipment necessary to successfully transport a continuous flexible material through various processes without defect. Enhancing Web Handling with proper equipment will ensure materials are processed at their maximum efficiency, allowing the process to generate maximum profits.

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