Wrinkles, winder

1. Wrinkles usually appear where there is too long a draw or unsupported length of web.
— may also be due to excessive tension that tends to exaggerate caliper differences across the web.
— crepe wrinkles are usually due to non-uniform tension wound into the roll.
2. Diagonal wrinkles result when web tension at one side differs from the other.
— often due to axis of unwind roll not at right angle to web travel or by soft edge roll where tension is not the same at both sides.
3. Wrinkles cannot be taken out by simply rewinding.
— wrinkles should be avoided in initial winding by moving backstand closer to winder or using an idler roll in a long draw.
4. If paper is thinner at center of unwind roll (baggy), a tendency to wrinkle occurs.
— adjusting the spreader bar can alleviate this.
5. For coated papers, the curved roll has to rotate to avoid scratching the surface.
6. Spreader bars or curved rolls may open up the center slit and crowd the side slits so that the rolls run together.
7. Wrinkles may arise if the rear winding drum runs slower than the web speed.
— this leads to bagging and the sheet wrinkles between the two drums.
— check for erratic tension in the sheet.
8. Wrinkles may appear between the rear drum and the riding roll if the riding roll is going more slowly than the web.
— adjusting the speeds of these rolls will correct the problem.
9. Check and adjust alignment of all rolls.
— check for slippage of drum rolls.