4 Most Common Roll Winding Defects
Troubleshooting roll winding defects and alerting winders and operators about problems on the web is critical to reducing scrap and improving throughput. Here are the four most common defects you should look out for:
1. Poor Roll Windings Starts
Problem: When you see an obvious difference between the web near the core and the remainder of the winding roll, you’re set for a poor start.
Solution: To prevent poor starts, tighten the web before fastening it to the core. Ensure you use good quality and properly stored cores. Begin with the proper torque, nip, or web tension.
2. Collapsed, Offset, Loose Cores
Problem: Core problems can stem from collapsed, offset, or loose rolls. Collapsed rolls stem from stacking rolls on end too high, with the bottom rolls crushing in an axial direction. An offset core causes an abrupt positioning shifting along the edge of the roll.
When the core is loose, it causes rotational displacement with the web, tearing free and causing control and tension problems with the next process.
Solution: Core problems start when you wind the web too softly. Wind it evenly, but harder at the start. Avoid stacking rolls too high to reduce offset. Make necessary tension adjustments gradually at the winder.
You can also easily restore a collapsed core with the Mark I and II Roll Savers. These roll savers allow you to reopen crushed cores for shaft insertion, saving rolls that would otherwise be scrapped, in turn saving you money.
3. Low-Quality Roll Edges
Problem: Poor slitting causes a rough, fuzzy, or dented roll-edged appearance. The edges may be frayed and upon closer inspection; the web edge isn’t straight. You may also see fibers within the packaging or on the film, or if you wipe the roll with a black cloth, it will become discolored due to the presence of slitter “dust.”
Solution: There are a few ways you can resolve this issue. First, ensure your slitters are sharpened. For shear slitting, be sure the slitters are adjusted and set properly for the right cant angle and blade overlap. Also, the slitter blades at the nip point should be moving slightly faster than the web (overspeed), so if it appears to be moving slower, you may need to adjust the speed differential between the web and slitters. If the current slitter setup is crush (score) or razor slitting, consider upgrading to shear slitting for better edge quality.
4. Telescoped or Dished Rolls
Problem: The defect shows a progressive roll edge misalignment that can be concave or convex.
Solution: Ensure caliper is consistent across the web width; Control tension throughout the wind; Ensure cores do not shift
This problem may indicate problems with an upstream process are creating thickness or moisture variations in the web that must be addressed. Proper torque transfer from winding shaft to core, along with precise control of web tension are also essential. Using a combination of tension controllers and quality winding shafts and chucks will ensure the tension remains where it should, and cores do not slip while winding. The ideal rewind tension profile to avoid dishing or telescoping is a harder start, smooth transition, and softer finish.
Winding defects create challenges for both the winder and the operator. You need to troubleshoot and solve most of these winding defects because it can save your company money and time. Restoring crushed cores can help from having to scrap deformed rolls, including those that are only slightly defective.
At Maxcess, we offer quality solutions such as crushed core restorers as well as accessories to maintain optimal operation of your winding shafts and chucks. Regular maintenance is suggested to keep your shafts and chucks in top condition, avoiding these top four common roll defects, mentioned above. If you do need service, we offer aftermarket service and support options to keep you up-and-running 24/7. Contact us today if winding defects are a significant issue for your company.