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Web Handling & Converting

Blogmaster: Dr. David Roisum

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Materials

28

Wishful Thinking - Baggy Webs

Posted by David Roisum on February 28, 2012
A few students are disappointed in the baggy web part of my Wrinkling module of my Web101 course.  What they expected was some ‘web handling tricks’ such as a tension setting or spreader or something that would make bagginess better.  However, by time they get to my class they&...

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Posted in: Materials, Problem Solving, Spreading, Upcoming Events, Wrinkling & Flatness
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09

Calculating/Determining Laminator Tensions

Posted by David Roisum on February 9, 2012
What should be the unwinding tension for 12 micron PET film and for 30 micron Polyethylene film.  Please give me the formula for calculating the rewinder tension for the laminate. I will use page 5.10 from the 2010 version of the Web101 notes.  I apologize for the mixed units, but we will...

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Posted in: Design, Materials, Measurement, Tension/Drive Control, Winding
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07

Web Smoothness, COF, Tension and Telescoping

Posted by David Roisum on February 7, 2012
We recently encountered customer complaint regarding roll telescoping.  Presently, we have the same tension settings for two different types of foil that have different roughness values. Would you recommend a higher or lower rewind tension for smoother foil surface (less roughness value)? Whil...

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Posted in: Design, Materials, Problem Solving, Tension/Drive Control, Winding
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31

Tension Guidelines

Posted by David Roisum on January 31, 2012
Tension Guidelines
Respected sir, I came upon a TAPPI standard that tension should be 10-25% of yield strength. 1. Is there any scientific rule to setting these value or are they heuristic? 2. What rule shall we follow in printed electronics industry? I am especially interested in the allowed variation fro...

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Posted in: Design, Maintenance, Materials, Rollers, Tension/Drive Control
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20

Rubber Cover and Chemical Incompatibilities

Posted by David Roisum on January 20, 2012
Metso has published another roller related article, this time a small laundry list of some rubber cover incompatibilities with certain chemicals found in the paper industry.  You can find a more in-depth discussion of the topic in the Rubber Roller Group Handbook and perhaps even more from your...

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Posted in: Design, Materials, Measurement, Rollers
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08

Winding pressure-sensitive materials

Posted by David Roisum on December 8, 2011
Winding pressure-sensitive materials
Q: I plan to wind large rolls of delicate material on a two-drum winder. I am concerned that pressures might emboss the tender coating. A: There are two pressures to be concerned with. The first is the external nip pressure between the wound roll and the drum. (Note a similar problem is the interna...

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Posted in: Materials, Nips, Problem Solving, Tension/Drive Control, Winding
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06

Winding Recipes

Posted by David Roisum on December 6, 2011
Winding Recipes
Q: I am looking for a "cookbook" for winding different type of materials. Specifically, a book that would explain what tension and taper (%) as well as nip should be used for each material in order to make perfect rolls. A: Unfortunately, there are no "recipes'"to make a perfect roll. To begin with...

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Posted in: Materials, Nips, Problem Solving, Safety, Tension/Drive Control, Winding, Wrinkling & Flatness
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29

(Over) Specifying Roll Diameter and Length Simultaneously

Posted by David Roisum on November 29, 2011
I am winding a fluffy product with final specifications on Outside Diameter and Mass. The basis weight and caliper (thickness) ranges are quite wide compared to the final product desired OD and mass. The density (basis weight/thickness) of the media definitely can change within the supply roll of me...

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Posted in: Design, Materials, War Stories in Web Handling, Winding
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22

Baggy Web Conversation

Posted by David Roisum on November 22, 2011
The following is historical fiction.  One where certain essential details are accurate, but the ‘conversation’ has been rewritten to protect the guilty. Dear Dr. Roisum, I was your student in a Converting School back in 20__. We now have a difficult web-handling problem caused ...

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Posted in: Materials, Measurement, Problem Solving, Rollers, Spreading, War Stories in Web Handling, Winding, Wrinkling & Flatness
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23

Dishing (, Progressive Symmetric) – Causes

Posted by David Roisum on August 23, 2011
Dishing (, Progressive Symmetric) – Causes
First, what is progressive outward symmetric dishing? The figure above shows A set of rolls wound on the same axis, such as in two-drum winding Each individual roll bows outward The amount of bowing increases the further the roll is from the centerline of the machine Each roll...

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Posted in: Materials, Winding
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Blogmaster

David Roisum photo

Dr. David Roisum

Dr. Roisum is a well-known authority in the area of web handling and converting. He has authored seven books, including Winding, Rollers and Web-Handling and has coauthored or edited several others. He was a technical editor for Converting Magazine with a monthly column entitled "Web Works." An accomplished professional speaker and instructor, Roisum has been praised for his skill at translating highly technical information into a common sense practical reference. Dave has been honored by TAPPI with their Finishing & Converting Division Award, Thomas W. Busch Prize and Finest Faculty awards and is a TAPPI Fellow. Dave received his Ph.D. from the Web Handling Research Center where he later became an Industrial Advisory Board member.

Dave has worked for the Beloit Corporation as a designer of winding machinery and later as a manager of research, and for Kimberly-Clark as a converting expert serving all business units. He is now a principal of Finishing Technologies Inc., providing consulting services to more than 300 clients who convert or manufacture: paper, film, foil, nonwovens, textiles and many other materials. He has accumulated much practical experience working in nearly 1,000 plants over the course of more than three decades.