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Machine characteristics can cause wrinkles

In the past few weeks we have talked about the causes of web wrinkles. Machine characteristics can also cause wrinkles. Here are a few examples:

Idler roll buckling or deflection causes wrinkles because the web will actually deflect out of its normal running plane at different intervals across the web width. This out of plane condition will occur wherever the greatest amount of deflection (usually the center) is in the idler roll. When roll deflection occurs, webs will wrinkle because they will compress toward the deflection point.

Air entrainment in webs as they flow over rolls will cause wrinkles. Air entrainment will create slippage between the web and the roll face. If this slippage occurs, then the web is not in traction with the roll. Air entrainment problems can be detected by viewing idler rolls that stop rotating during the converting process. Also, if wear spots are seen across idler roll faces, air entrainment is probably the problem. Machinistsí bluing dye can be applied to idler rolls where air entrainment is suspect to detect wear spots.

Material roll buckling or deflection. If the parent roll deflects on its support mechanism (air shaft, mechanical chucks or core cones mounted on a steel through shaft) then compressive forces will cause the material roll to buckle and wrinkle before the web enters the converting process.

Varying tension through several different types of processes in one converting line will cause wrinkles. A good example of this is tension through a coating section, printing process, drying section and slitting section. Tension through the coating section may be high, then through the printing process may be lower, then through the drying process lower yet, then through the slitting section may be high again. Wrinkles will occur under these conditions because the web will stretch and contract creating compressive and decompressive forces.

**DISCLAIMER - A great deal of time has been invested in the development of our weekly tech tips. To the best of our knowledge, they are accurate. It is up to the user to verify all results.


Converter Accessory Corporation
201 Alpha Road
PO Box 188
Wind Gap PA 18091-0188

Phone (800) 433-2413 -(610) 863-6008
Fax (800) 709-1007 - 610) 863-7818

What is Web Handling?
Web Handling is the science, engineering and equipment necessary to successfully transport a continuous flexible material through various processes without defect. Enhancing Web Handling with proper equipment will ensure materials are processed at their maximum efficiency, allowing the process to generate maximum profits.

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