Results of Research on Running Paper Webs Through Printing Presses.

Paper rolls must be wound at high web tensions at the mills so that the rolls can be shipped without telescoping. Web tensions normally desired on printing presses are appreciably lower; giving a factor of safety over proven paper strength of the order of ten. Therefore, defects in paper are not a primary cause of web breaks; breaks in a running web are due to abuse. Breaks occurring at defects in the web are exactly similar to a chain that breaks at its weakest link. It is a general belief in the industry that web weave (indeterminate side-lay position of the web) is due to variations in the paper. Drastic localized variations in the paper induced by water mist spray show in laboratory tests to be incapable of producing web side-lay by themselves. Investigation showed that web breaks and web weave are caused primarily by misalignment in the machine, due to causes not previously considered. Scale models are available for demonstration. New features now being introduced in press designs will make web breaks and web weave very rare; reducing spoilage and production costs, while improving quality.