How to Re-Thread the Paper Web After a Paper Break in the Forming Fabric Section

After the paper breaks, the forming fabric is resized, and sheets of paper quickly begin to form on the fabric surface again. When they see the sheets taking shape, many people’s first reaction is: “It’s time to pull the paper off.”

However, “there is paper on the forming fabric” does not mean “the paper sheets can be smoothly transferred to the press section”.

If the paper sheet is slightly damp, has loose edges, or keeps following the forming fabric to the transfer point, it will likely break again at the first press inlet, even if it is barely joined afterward.

Before restarting paper feeding, forming section operators should check more than just whether a sheet has formed. They also need to confirm that the sheet is forming properly, draining well, and transferring smoothly to the next section.

Check the Forming Fabric First: Is the Sheet Forming Properly

After re-sizing, don’t just check whether pulp is flowing out of the headbox. Also make sure the paper web on the forming fabric is continuous and smooth.

If the sheet is already unstable on the forming fabric, feeding it into the press felt section usually won’t fix the problem on its own. In particular, when cracks keep appearing along the edges, you must first determine whether the issue stems from a localized forming problem or from abnormalities in dewatering, spraying, or edge treatment.

When the paper turn up tape is narrower, you also need to check whether it can remain continuous.

Check Dewatering Next: Is the Sheet Too Wet or Too Soft?

Forming section staff can compare on-site observations with trends:

• Is the water on the forming fabric draining away as it normally does?
• Have there been any noticeable changes in the discharge of white water?
• Does the paper sheet appear noticeably wet and limp when it reaches the end of the forming fabric section?

If the paper sheet is noticeably damp, simply increasing the tension to pull it through may cause it to tear as soon as it leaves the forming fabric.

The Key Check: Can the Sheet Transfer to the Press Felt Properly?

The forming fabric section produces the paper, but this is only the first half of the process. Whether the paper feed can proceed smoothly depends on whether the sheet can stabilize as it leaves the forming fabric at the suction transfer point and adhere to the press felt.

Several common symptoms observed on-site often point to different areas for troubleshooting.

• The paper sheet continues to follow the forming fabric and cannot be smoothly removed from the fabric. Special attention should be paid to inspecting the sheet’s off-fabric condition, the suction and transfer vacuum, and the transfer conditions. All of these problems should not be resolved solely by increasing the traction at subsequent stations.
• The sheet has come off the forming fabric but cannot adhere steadily to the press felt. A determination should be made based on the suction-transfer vacuum, the operating condition of the press felt, and the moisture content of the paper sheet to confirm whether the problem stems from an unstable suction-transfer process or from the paper sheet itself having excessive moisture content or insufficient strength.
• The paper sheet transfers successfully from the forming fabric to the press felt, but the edges repeatedly detach. In addition to checking the suction and transfer conditions, you should also further investigate edge formation, paper edge handling, and localized dewatering.