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Viscoelastic web curl due to storage in wound rolls, TAPPI Journal July 2020
ABSTRACT: Winding is often the final operation in a roll-to-roll manufacturing process. Web materials, i.e., materials that are thin compared to their length, are wound into rolls because this form is the only practical means to store them. The resulting bending strains and associated stresses are large for thick webs and laminates. As many webs are viscoelastic on some time scale, bending stresses lead to creep and inhomogeneous changes in length. When the web material is unwound and cut into discrete samples, a residual curvature remains. This curvature, called curl, is the inability for the web to lie flat at no tension. Curl is an undesirable web defect that causes loss of productivity in a subsequent web process. This paper describes the development and implementation of modeling and experimental tools to explore and mitigate curl in homogenous webs. Two theoretical and numerical methods that allow the prediction of curl in a web are developed: a winding software based on bending recovery theory, and the implementation of dynamic simula-tions of winding. One experimental method is developed that directly measures the curl online by taking advantage of the anticlastic bending resulting from the curl. These methods are demonstrated for a low-density polyethylene web.
Journal articles
Magazine articles
Wet pressing and product quality: Review of previous pilot machine trials, TAPPI Journal July 2020
ABSTRACT: The purpose of wet pressing is to remove water by mechanical means to consolidate the web and minimize the energy expended in the dryer section. In this process, paper is compacted and densified to degrees that impact end-use performance. Average density is increased by pressing, which has implications for grades where stiffness is important. The z-direction density gradients can affect printing and converting. Lastly, pressing affects surface quality of paper and its response to printing. Broadly speaking, the final press nip dominates the paper surface roughness and the early press nips affect printing performance.
Journal articles
Magazine articles
SetPoint: Reach Out and Touch Someone, Paper360º July/August 2020
SetPoint: Reach Out and Touch Someone, Paper360º July/August 2020
Journal articles
Magazine articles
Social Influence—A Prime Driver of Workplace Safety, Paper360º July/August 2020
Social Influence—A Prime Driver of Workplace Safety, Paper360º July/August 2020
Journal articles
Magazine articles
Paper Machine Water Efficiency, Paper360º July/August 2020
Paper Machine Water Efficiency, Paper360º July/August 2020
Journal articles
Magazine articles
Industrial LED Lighting Improves Pulp & Paper Mill Safety, Paper360º July/August 2020
Industrial LED Lighting Improves Pulp & Paper Mill Safety, Paper360º July/August 2020
Journal articles
Magazine articles
TAPPI Journal Summaries, Paper360º July/August 2020
TAPPI Journal Summaries, Paper360º July/August 2020
Journal articles
Magazine articles
Invisible Waste in Maintenance Organizations, Paper360º July/August 2020
Invisible Waste in Maintenance Organizations, Paper360º July/August 2020
Journal articles
Magazine articles
TAPPI News, Paper360º July/August 2020
TAPPI News, Paper360º July/August 2020
Journal articles
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ASPI News, Paper360º July/August 2020
ASPI News, Paper360º July/August 2020