Single Ply Medium Delamination Issues
By Ralph Young
September 20, 2023
Laurie asks:
We are experiencing issues with rolls of single ply paper delaminating. What has been your experience with this?
It all starts with fibre quality. Ideally the strongest medium sheet would be made with a very high percentage of hardwood fibre and it’s usually a more consistent sheet. When we move to recycled fibres or test mediums, we can experience weaker sheets and ones with more machine and cross direction variations.
In my forty years in this industry this is the first time I have heard of a single ply sheet decapping or delaminating cleanly. There can be a few possible reasons for this. To reduce costs while still producing a commercially acceptable product, mills often add mixed office waste to the OCC/DLK fibres. When unliked fibres of different qualities are blended issues can occur. A paper mill should clean and refine these recovered papers separately, but this rarely happens. It can be labor intensive and adds cost to the product. Mediums are only as strong as the fibre-to-fibre bonding within the sheet. This action occurs in the wet end of the paper machine with the drainage action on the wire, and later in the dewatering in the dryers where the consolidation of the fibres occurs. It may be in one of these areas that the issue manifests.
The age and sophistication of the paper machine also has an influence on the quality of the finished product (the paper rolls).
You might also want to look at CD caliper control and monitor the dryer cans across the paper machine. Let me know if you want me to take a deeper dive into this topic.
— Ralph
Technical questions?
