Four things you need to know about press felts

Press felt is a key technical fabric in the press section of a paper machine. The press device plays an important role in the operation of the paper machine. It squeezes out the moisture in the wet paper through mechanical squeezing to improve the dryness of the paper web and improve the strength and tightness of the paper. The press felt plays an important role in this process. It can be used as a dehydration medium and can be used to transport the wet paper into the drying section.

The Role of Paper Making Press Felt

• Water filtration: As a dehydration medium, the press felt absorbs excess water from the wet paper through its own structure during pressing and achieves efficient filtration.
• Smoothing: During the paper web transfer and modify, it smoothes and modifies the paper surface and helps the subsequent drying and coating process.
• Transmission: Supports the wet paper web to enter the drying section and drives the rollers in the pressing section to operate, so that the paper sheets pass smoothly through the pressing section and maintain continuous and stable operation of the paper machine.

The water squeezed out of the wet paper web by the pressing device must pass through the press felt before it can be finally removed. If the press felt’s water permeability is poor, the squeezed water will re-enter the paper web after it leaves the press, reducing its dryness. This will increase the moisture content of the paper web entering the drying section, which will greatly increase the drying energy consumption. The increased moisture content of the paper web will force the paper machine to slow down, which will also lead to a reduction in production.

In addition, if the performance of the press felt is too poor, it will cause some paper defects and reduce product quality. It can be seen that the press felt is an important factor for the pressing device. It is directly related to the dehydration efficiency of the pressing device, the internal and external quality of the paper, and the production efficiency of the paper machine.

What Should be Paid Attention to When Using Press Felts?

Selection of paper making press felts

Choosing the right press felt is not simple. There are many types and models. The best press felt is not necessarily the right one. The choice of felt depends on the type, quantity, surface requirements, pulp properties and use environment of the paper produced.

Convenient replacement of paper making press felts

Paper making felts have a certain working life. When the working performance of the press felt cannot meet the production requirements, it should be replaced with a new one as soon as possible. Otherwise, the paper machine will not be able to run at normal speed and the paper quality will be adversely affected. Things to note when replacing: arrange the replacement time reasonably, and replace the paper making felt as much as possible during the shutdown and maintenance period; the design of the frame, pressure roller and other components of the pressing section should be scientific and reasonable to facilitate disassembly and lifting, with sufficient distance and space; try to increase the number of carrying roller on the outer ring of the press felt and reduce the number of carrying roller on the inner ring of the press felt, and at the same time, try to reduce the number of carrying roller while meeting the press felt operation requirements; when replacing hard and thick paper making felt, special claws can be configured or a special traction belt can be sewn on the transmission side of the press felt to facilitate pulling the press felt into the transmission side.

Shorten the initial adaptation period of paper making felts

After the installation of a new press felt, its surface flatness, fiber arrangement direction, moisture content and air permeability cannot meet the requirements of the paper machine to operate at normal speed and produce high-quality products. It needs to be idle for a period of time or used at low speed for a period of time before it can reach the ideal use state.

Strengthen the maintenance of paper making press felts

The important tasks of press felt maintenance include: regularly checking the position of the press felt to prevent it from wrinkling and deviation, which will cause mechanical damage to the press felt; maintaining an appropriate and stable tension. If the tension is too low during the operation of the press felt, it is easy to slip, which seriously affects the quality of the paper. Excessive tension will affect the dehydration efficiency, shorten its life and increase the stress of the rollers in the press section, which may easily cause equipment damage; and cleaning the press felt regularly.

Paper making press felts, as a key consumable in paper machines, constantly impact the quality, output, and yield of paper produced. They also significantly influence machine speed and energy consumption. Therefore, press felt is also one of the important factors for the efficient operation of paper machines. In production, it’s crucial to select the right press felt to best suit both the paper produced and the paper machine. Quick felt replacement and a shortened initial adaptation period can maximize paper machine efficiency. Press felt maintenance is also crucial to maintain optimal dewatering performance.