Importance of torque capacity in predicting crepe wrinkles and starring in wound rolls

Abstract

Roll models provide information about the radial stresses and circumferential stresses that exist in a wound roll of web material. A derived quantity that is available from the radial stress profile is the torque capacity. The torque capacity is the ability of a wound roll to resist slippage when subjected to external torque. Crepe wrinkles that occur in wound rolls have been attributed to slippage. The literature available on crepe wrinkle formation is nebulous with respect to quantitative evidence available to identify parameters that contribute to the formation of the defect. A parameter associated with the winding machinery is the deceleration that rolls undergo. A method to predict crepe wrinkle formation due to slippage that results during deceleration will be presented with quantitative evidence. Starring has been attributed to negative circumferential stresses that exist in wound rolls. Slippage has never been identified as a factor that contributes to star formation. This study identifies the importance of torque capacity as a means to predict starring in center-wound rolls, and provide quantitative evidence from experimental data to support the fact that in some cases slippage is a precursor to star formation in center-wound rolls.