Web breaks in the paper machine press section are rarely attributable to one isolated factor.
When visible mechanical and surface-related causes have already been investigated, troubleshooting should move toward the process settings and operating parameters that directly influence wet-web strength, dewatering and sheet transfer.
A logical analysis should progress from simple variables toward more complex interactions between process conditions and equipment performance. 断纸排查英文0927
Correct nip loading is important for both dewatering and wet-web stability.
When the load applied at a press nip is excessive, the wet sheet may be crushed or mechanically damaged. This can increase the likelihood of web breaks.
Insufficient loading creates a different problem.
Poor press dewatering can leave excessive moisture in the sheet. Since the wet web has limited strength, a wetter sheet may become less stable during subsequent transfer.
The relationship can be summarized as:
Insufficient Nip Loading → Reduced Dewatering → Higher Sheet Moisture → Lower Wet-Web Strength
Operators should also review how the load is distributed among the individual press nips.
Balanced load distribution helps maintain stable press-section operation rather than placing excessive demand on one particular nip.
Speed relationships are another important factor in web-break analysis.
The Speed Differential / Draw and web tension should be checked between different press-section positions and particularly in combined or compact press configurations.
The transitions between:
Forming Section → Press Section → Dryer Section
also require attention.
Excessive draw can stretch the wet sheet beyond its available wet-web strength.
This risk becomes more significant when sheet strength is already reduced by high moisture, furnish conditions or other process factors.
Where a rope threading system is installed, inspect the carrier ropes and associated components for correct condition, alignment, tension and operation.
The press felt cleaning and lubrication system directly affects felt condition.
Check the flow rate and operating pressure of:
Press Felt Lubrication Showers
and:
High-Pressure Cleaning Showers
Incorrect shower conditions can influence felt cleanliness and permeability, which in turn affects water removal and sheet release.
Shower performance should therefore be evaluated as part of the overall press-section process rather than only as a felt-cleaning issue.
If web-break frequency changes unexpectedly, review recent process adjustments.
Has the mill changed:
Stock Furnish?
Fiber Composition?
Retention Program?
Drainage Program?
Dry-Strength Agent Dosage?
Other Wet-End Additives?
Chemical dosage can influence several properties simultaneously.
Both excessive and insufficient dosage may affect fiber bonding, drainage behavior, sheet formation and final paper strength.
Consequently, changes in wet-end chemistry can indirectly increase the probability of web breaks even when the mechanical equipment itself is operating normally.
Once the obvious equipment-related causes have been eliminated, a useful sequence is:
Nip Load → Nip Load Distribution → Speed Differential / Draw → Web Tension → Shower Flow and Pressure → Furnish Changes → Chemical Dosage
The variables should be checked systematically rather than adjusted simultaneously.
This approach makes it easier to identify which process condition is actually affecting wet-web stability.
Since 2008, Huatao Group has been engaged in the production and global supply of pulp and paper machinery, equipment and spare parts.
Our product portfolio includes Press Felts, Dryer Fabrics, Forming Fabrics, Suction Press Rolls, Blind-Drilled Press Rolls, Jumbo Press Rolls, Pickup Rolls, Dewatering Elements, High-Vacuum Suction Boxes, Low-Vacuum Suction Boxes, Water-Leg Suction Boxes, Doctor Blades, Doctor Holders, Shower Systems and Papermaking Chemicals.
For paper machine troubleshooting, equipment upgrades and spare parts, please contact:
Huatao Group
Website: www.huatalover.com
Email: service@huataogroup.com
WhatsApp / WeChat: +86 177 78255675
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