The Holy Grail, Six Tips for Winding
- Published: June 30, 2011, By Duane Smith, Davis-Standard Converting Systems
1. Be sure the web material is as flat as possible |
Process coming into the winder needs to be consistent |
Basis weight and moisture variations must vary <5% across the web |
The winding operation cannot improve the web material |
2. Incoming web tension must be under control and measurable |
Web tension cannot vary more than ±5% during steady state winding from setpoint |
Web tension cannot vary more than ±10% during acceleration and deceleration |
Transducers need to be provided for a direct readout of incoming web tension |
3. Start winding with a good foundation |
Wind on as large a core outside diameter (OD) as possible |
Start winding on a good quality, well-dried core |
Start winding with first wraps on the core as tight as possible |
4. Wind with tapered roll hardness |
After achieving a good hard start, taper the roll hardness as the roll winds |
Gradually taper roll hardness through one or more of the TNT Principles |
Taper the roll’s hardness between 25%–50% of starting hardness |
Hardness tapering prevents defects such as dishing, starring, buckling, telescoping while unwinding |
5. Avoid winding too tightly as excessive roll harness can cause the following problems |
Blocked rolls with sheet layers that fuse or adhere together |
Exaggerated web defects, such as high caliper areas building on each other |
Gauge bands that produce corrugations or rope marks in the tightly wound roll |
Bagginess upon unwinding |
6. Wind sufficient air in low areas and prevent stretching over high areas |
Davis-Standard: www.davis-standard.com