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Blogmaster: Dr. David Roisum

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Rollers

26

Load Cell Roller Wrap Angle

Posted by David Roisum on April 26, 2012
Load Cell Roller Wrap Angle
The load cell manufacturer can not make general recommendations for wrap angle.  The value for minimum wrap angle depends on all of the things needed for sizing (selecting maximum capacity) a load cell such as tension, width, roller and fixture tare weights and so on, all of which can not be kn...

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Posted in: Design, Measurement, Rollers, Tension/Drive Control
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24

Wrap Angle Rock Around the Clock

Posted by David Roisum on April 24, 2012
Wrap Angle Rock Around the Clock
At uber, ultra, very, big, great risk of over-generalizing and over-simplifying, I would like to offer you some ideas on some application range for wrap angles.  The application ranges include idlers, tendency and driven rollers and include systems that are and are not wrinkle-prone.  Here...

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Posted in: Design, Rollers, Spreading, Wrinkling & Flatness
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05

Worst-Case:? - Moderate Misalignment

Posted by David Roisum on April 5, 2012
Many states have Good Samaritan laws that protect well-meaning first responders who try to help accident victims from liability and lawsuit.  However, there is no Good Samaritan exemption from the brutal laws of physics.  So, even moving in the correct direction could make things worse.&nb...

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Posted in: Problem Solving, Rollers, Spreading
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28

Speed Limit - Machine

Posted by David Roisum on March 28, 2012
Aside from wound roll vibration, most machine speed limits are few.  These include such things as drive power, bearing rpms and critical speed (a topic that has enormous misunderstanding that may be worth revisiting in a future post).  Since the additional mechanical costs of a machine tha...

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Posted in: Design, Rollers, Tension/Drive Control
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26

Speed Limits - Web Handling

Posted by David Roisum on March 26, 2012
Speed Limits - Web Handling
There are only two speed limits in web handling that I am aware of.  The first is air entrainment.  This is easy to counter on rollers by roughening them to give them air-handling capabilities.  (You may have to avoid annular or spiral grooves for very thin products, as they might ten...

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Posted in: Design, Rollers, Winding
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20

Wound Roll Wrinkles – Bottom of the Roll

Posted by David Roisum on March 20, 2012
The bottom of the wound roll is especially wrinkle prone.  Here, the core has a geometry an order of magnitude cruder than a roller.  Here, the first wraps are likely ugly.  Here, the bending stiffness of a center-wound system is limper than a wet noodle.  Here, we have tension a...

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Posted in: Rollers, Winding, Wrinkling & Flatness
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09

Which Roller Moved the Web - Witness Lines

Posted by David Roisum on March 9, 2012
How many times I wished I had a portable edge sensor to do problem solving in a plant (something like an IR camera, very useful but seldom found.)  So, I make do by putting a witness line on a roller just outside of the equilibrium path of the web.  This makes path changes very easy to see...

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Posted in: Guiding, Maintenance, Problem Solving, Rollers
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07

Which Roller Moved the Web – Traction Change

Posted by David Roisum on March 7, 2012
It does little good to say your machine is crooked (even if it is).  That would be just whining.  Nobody likes whiners.  Instead, we should strive to be good complainers instead.  By complaint, we mean so specific as to be literally able to touch the thing that is wrong (crooked)...

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Posted in: Guiding, Problem Solving, Rollers, Tension/Drive Control
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05

Web Path Changes During Speed Changes

Posted by David Roisum on March 5, 2012
Web Path Changes During Speed Changes
Path changes during speed changes are a common (and usually avoidable) problem.  In winding the resulting defect is given a special name:  acceleration offset.  Unfortunately, the name does not reflect the true mechanics of the problem.  It is not acceleration per se.  Inste...

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Posted in: Guiding, Problem Solving, Rollers, Tension/Drive Control, Winding
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13

Cooling Rubber Covered Rollers and School

Posted by David Roisum on February 13, 2012
Cooling Rubber Covered Rollers and School
Metso’s Up and Running E-news has another roller related article.  This one is on Guidelines for Internal Water Cooling of Rubber Covered Rolls.  While it is considered tasteless to critique an article when you yourself have not written anything better (or at all) on the subject, I o...

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Posted in: Design, Maintenance, Nips, Rollers, Temperature/Moisture Effects
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Blogmaster

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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.