User's Manual for the Wrinkle Troubleshooter

The Wrinkle Troubleshooter app can help you diagnose dozens of types of wrinkling and flatness problems. Remedies are suggested for each root cause. All that is required to get started is to pay close attention to the appearance of the wrinkle. This might be the angle of the wrinkle or it could be the pattern of the wrinkle or both, such as a wrinkle at an angle on one side of the web. To make the wrinkle most visible, you can use a variety of techniques such as adding incident (side angle) lighting, lowering speed to thread speed (when possible), changing tensions and using flat webs (when checking for machine problems). Make sketches of the wrinkle patterns, take pictures and teach these observational techniques to operators who spend more time at the machine and are thus invaluable for gathering necessary information.

The severity of the wrinkle is much less useful for troubleshooting than it is for QA. In fact, we should be able to determine root causes when the web merely ‘troughs’ in the span between two rollers. By ‘troughing’ we mean that the web is not as flat as a table top. We can usually see everything we need about the problem long before the QA department or customer complains, which is usually when the web bulges or creases over a roller. In this regard, troughs in the open web span are not just risks of customer complaint; they are where we do most of our troubleshooting work. Waiting until the web folds over on a roller is not necessary and is not helpful.

When diagnosing and treating a specific wrinkle, it is very important to think locally. In other words, a specific roller might be causing wrinkles so that treatments might need to be at that roller. One roller upstream is too early (there is no complaint there) and one roller downstream may be too late. In some cases, such as misalignment and spreading, we might need to consider the interaction of 2 or at most 3 rollers. However, in many cases the diagnosis and treatment of wrinkles is very very local. An exception to thinking locally is poor raw materials, such as baggy webs, that could trouble several parts of a machine.

Most wrinkles are quite tension sensitive even if only a very few types are directly caused by tension. Operators should know whether high or low tension is helpful with regard to reducing wrinkle incidence/severity. They should also know what limitations to tension there might be imposed by process and/or machine. Since tension settings are easily changed on most machines, it is a place to start, even if only to ‘open up the window’ a bit. However, this app focuses on root causes where some of the most reliable remedies will be found.

Other web handling tools for preventing wrinkles are spreaders. Experience teaches us that prevention might be easy, but removing wrinkles is hard and is almost certainly too late. However, even though spreading might help reduce wrinkling incidence/severity; spreaders are costly and complex. Worse yet, SPREADERS CAN CAUSE WRINKLES if not properly applied.

A lesser-known general technique for preventing wrinkles from getting started is called 'flattening.' Here, we reduce the web-roller traction to just enough to turn the roller, but no more because that will increase the risk of wrinkling. The easiest way to reduce traction is to add Teflon tape or other slippery material to an offending roller. Other ways include unwrapping it, increasing roller diameter and increasing web speed (for smooth materials to encourage a bit of air lubrication).

A few situations might be complicated by having more than one type of wrinkle. It is also common to have more than one location in a machine where wrinkles tend to form. The user should try to diagnose only one wrinkle type and only one location at a time, before proceeding to the next type and location.

For anyone struggling with wrinkles and most any other type of web defect, the must-have book, Roll and Web Defect Terminology by TAPPI PRESS belongs on every bookshelf. There you will find a whole chapter on wrinkling. Another resource is the Roisum Library AbbottApp. Here you can search and find 200 articles on wrinkling and another 100 on spreading. Finally, the Web101.09 and Web101.10 modules from my Web Handling and Converting short courses teach wrinkling and spreading.

Navigation of this app is easy. Merely click on the button for what you think is the closest case to your wrinkle and follow the troubleshooting tree until you reach the root cause for your specific wrinkle.


© Copyright 2012 David R Roisum, Ph.D and Steven Abbott TCNF