Century of web handling literature

This paper is a review of some 3,500 published works in the areas of web handling, winding, converting and related subjects. These individual works include articles, books, columns, conference papers, instruction manuals, theses, course notes and other material spanning the better part of a century. There are hundreds of authors that have contributed to this vast body of industrial art and science. These authors represent scores of companies, independent consultants, universities, trade organizations and trade publishers. The individual works were found by a combination of professional and public database searches as well as direct inspection of collections at libraries, attendance at conferences, magazine subscriptions, websites and other sources. These original works were then inspected for the bibliographies contained therein and added when new and relevant items were found. All web related works were entered into a flat database of a dozen fields that extended beyond the obvious (author, title, publication) to include such information as author's employer, copyright holder, rating and other fields. The search and database construction took place over the course of a quarter century.Analysis of this database within this paper includes a study of publication counts by author, subject, type and source. While the great majority of authors have only a single or a few web handling publications, some of those are uniquely valuable as they may be the only treatment of a particular topic. A handful of authors have more than one-quarter century of steady publication. Even so, the most prolific author still only accounts for less than 10% of the total. The organizations that account for the majority of the web related publications include TAPPI, Paper Film Foil Converter Magazine, the Converting Magazine, AIMCAL and, of course, the Web Handling Research Center. The publication count ranking nearly matches the age of the major organizations, possibly suggesting a steady publication rate. Unfortunately, the overall publication rate seems to show the common life-cycle pattern of development, introduction, growth, maturity and decline. If TAPPI publications are not considered, because the paper industry has been in a decade plus long decline, the remaining publication rate seems to be holding since its peak in the mid 1990's. A prospective of near future publication is also given

Optimization by integrating engineering and business models

To optimize is to find the "'best" solution given certain conditions and constraints. What is meant by best and how to find it has received scant attention. To the engineer, "best" may be fastest, strongest, most reliable and so on. The engineer will have models to determine whether one solution is better than another based on objectives such as these. "Best" in business is quite different. It means to maximize profit or minimize loss. The economist or accountant also has models. Note the obvious disconnect between the objectives of engineering and business models. This disconnect has hindered us from finding a practical best to improve profit on the plant floor. Simple questions like "what is the best tension to run" have no useful answers from a strictly engineering or business viewpoint.This paper begins by defining best for several familiar examples. However, it quickly concludes that the only "best" that makes sense in an industrial environment is that which will minimize total costs. To find this best we must integrate engineering and business models. This technique developed here is very powerful, flexible and adaptable approach. The technique can be applied explicitly using calculus or similar numerical techniques when cost functions are well known. Even more flexible is an implicit approach which can be used when very little is known about costs. Five web handling examples are used to illustrate this problem solving technique. These examples include a variety of objectives such as optimum rejection levels, core waste, web tension, and layon roller nip and water flow rate. These examples show how it is easy to combine apples and oranges, such as waste and delay, when one converts to a common denominator of cost

Reading a roll

Web or winder defects often leave a visible record of themselves in the wound roll that can be read much like the rings of a tree. Varying strains in each layer as it is wound will cause changes in geometry that can be observed visually or with simple tools. These cylindricity deviations are a fingerprint of the cause of the defect.This paper shows how to read a roll's history by diametral variations across its width, by radial variances around the periphery, and by variations in width or CD position. Additionally, the winding mechanics that produced the cylindricity deviations will be discussed. Defects covered include corrugations, dishing, ridges, starring, telescoping, and many others

Web bagginess: Making, measurement and mitigation thereof

Web bagginess is a defect so tenacious that few machines will totally escape its grip. It is so pervasive that it can be found on materials as diverse as tissue, writing paper, carpet, nonwovens, plastic film and steel. It is so chameleon-like in its appearance that it is given many aliases such as baggy lanes, camber, layflat, puckers and many more. Yet as common as this ailment is, objective measurements are tedious or fraught with uncertainty or both. This means that culling and rejection is typically done by subjective visual appearance. As common as this ailment is, few can take a specific baggy lane and point to the machine element that made it, much less how it was made.This paper begins by defining bagginess in three entirely equivalent ways based on variations of flatness, stress and strain. It then develops a taxonomy of bagginess by classifying the general case into major groups depending on how the stress variations are distributed. Next, it discusses all of the common and most of the arcane means of measurement. Each is described by principle of operation, application and practical difficulties. Next, the more common sources of bagginess, such as nonuniform formation and yielding during handling are described. Finally, a methodology is developed for troubleshooting bagginess whose source is not certain

Guidelines for allowable in-plane roller misalignment using wrinkling and web break models

While we have had wrinkling and web break models for a quarter century and the means for precision roller alignment for a half century, no consistent recommendations have been made as to allowable tolerances for roller misalignment. The lack of consistency is not so much due to variability of web properties or web machine specifics. Rather, it is mostly due to cultural reasons. The paper industry typically specifies what it could do rather than necessarily what it should do and is a fraction of one hair's breadth for dry end equipment. The converting industry, in contrast, is largely silent on the subject of alignment and thus leaves it to every individual involved to figure out or, more likely, guess at what needs to be done.This paper proposes guidelines for allowable in-plane roller misalignment, the more critical of the two directions, based on well-tested wrinkling and web break models. The wrinkling criteria is lack of wrinkles crossing a roller at any value of tension. The web break criteria is limiting maximum tension (at the outside of the bend) to twice the average and thus keep the inside of the bend from going into compression. For those who do not wish to use models, an experimental technique to obtained allowable in-plane misalignment is also described. For those who do not wish to use either models or experiment, a set of quality classes is described that captures best practices in some of the more common web applications.This paper also includes a few parametric studies revolving around some of the more common materials such as paper and thin films that will show what sensitivities are important and what might be safely ignored. All of this is aimed at what should be done, i.e., when should a roller be moved. Finally, a brief review of alignment methods and tools describe what we could do in a commercial setting. In other words how close can we expect roller alignment to get when we choose to move a roller

10 commandments of web machine design

This paper describes the most important aspects of roller design, selection and maintenance necessary for a smooth running web process. Included are discussions of alignment, deflection, geometry, surfaces, traction, and tension control. Design criteria for sizing and tolerancing rollers will be given which are based on web handling mechanics. Also given are simple field checks for a quick evaluation of existing machinery

Thinking thin?

Markets drive us to ever thinner webs to reduce material costs and waste going to the landfill. The challenges for running a lighter basis weight or thinner caliper are at least as difficult for web handling as they are for web manufacturing. However, these challenges may not be as familiar as more commonly known machine limitations such as width or speed. Because they are not as familiar, they may catch us off guard. The challenges described in this paper include: wrinkling, air entrainment, tension control, roller design, problems associated with profile variations and others