EVOH allows conversion from foil and metallized film laminations to co-extruded barrier films.Read more
Mark Miller helps you identify the right material selection for tooling that will carry fluid to your substrate.Read more
Product and Technology of the Year Awards praise Hazen for Titleist golf ball sleeves and cartons and SAM N.A. for slot die with internal …Read more
Web handling expert Tim Walker offers three options for this machine direction folding process.Read more
News | New Products
EcoTag I and 2 synthetic paper is said to offer high quality type and other properties in demanding narrow web uses
Company will feature live demonstrations of lamination and web handling at opening of new, larger North American location
Frito-Lay floor stand honored as Temporary Display of the Year and Most Creative Temporary Display
Demand for space is said to be strong for the 2016 trade fair for plastics and rubber, with 3,000 exhibitors expected to fill the halls
The 3600 Series undergoes an engine upgrade to run at higher speeds, reportedly with no loss in print quality
The Solution Coating Technical Center will offer customer trials and demos, toll coating, and R&D for the coating industry
The Tau 330 UV inkjet digital label press is said to provide up to 2 hours of uninterrupted printing, fewer changeovers, and less downtime
Directories | Reports
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Visit Mark's Coating Matters from fluid coating expert Mark D. Miller; Process improvement and project management for precision roll-to-roll coating applications.
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- August 10, 2012
WebHandlersQuiz 18 continues the Q&A format I began this past February with our quest to address fundamental questions concerning web handling. To see past Quiz questions and answers, visit: pffc-online.com/blog/walker.
So this blog posting continues to focus on the subject matter we began in July, which is Winding–If you wind a paper and a film product of equal thickness and roll geometry at the same combination of winding conditions (tension, nip, taper, speed), which will likely have higher internal roll pressures or greater tightness?
The mostly likely answer is the film product will wind a much tighter roll, especially if it is a lower modulus film, such as polyethylene or polypropylene.
Paper products tend to wind looser rolls since they have a high relative compressibility in the radial direction, and the web stretch (a.k.a. strain) in the paper layers can lose their tension from radial shifting or compressing of the roll’s core and inner layers.
Film products tend to wind tighter rolls since they have a low relative compressibility in the radial direction, and the web strain (especially in stretchy films) in the film will have minimal tension loss from radial shifting or compressing of the roll’s core and inner layers.
One exception might be high speed winding of a smoother film without control of the entrained air layer compared to a more porous paper. While paper can absorb an entrained air layer, films will capture the air between layers. Over time, the air can bleed out of a film roll, causing it to loosen and potentially giving rise to a looser condition than paper on the same winder.
More on this topic was covered in this archived Web Lines column: The Pressure of Winding Rolls, May 2006.
Stay tuned to this blog for more Q&A. My next Quiz will feature still another facet of Winding involving the advantages of using a nipped or gap-controlled roller ahead of winding.