What is Press Felt? A Detailed Explanation

In the world of papermaking, there is a material that quietly plays a key role, but few people know about it. It is hidden in the high-speed running paper machine, silently taking on the important mission of transforming wet pulp into smooth paper. This material is Press Felt.

Read this guide to learn everything about press felt.

• What is Press Felt?

• Press Felt Categories

• Press Felt Structure

• Features of Press Felt

• Press Felt Production Process

• Application areas of Press Felt

• Selection and maintenance of Press Felt

• Latest technologies and future trends

• Conclusion

What is Press Felt?

Press Felt is a key consumable used in the papermaking industry and is an important component of the press section of a paper machine. It is a specially designed textile material made of synthetic or natural fibers that is used to support and guide the paper during the pressing process to dewater.

The main function of Press Felt

1. Auxiliary dehydration

In the papermaking process, after the pulp is formed by the wire, it still contains a large amount of moisture (usually more than 80%). The press felt exerts pressure on the paper sheet through the mechanical action of the press section and cooperates with the press roller to squeeze out the moisture in the paper sheet, while absorbing some of the moisture through its own structure.

2. Transfer pressure

The press felt can evenly transfer the mechanical pressure of the press section to the paper sheet, ensuring that the thickness and density of the paper sheet are uniform, thereby improving the physical properties and quality of the paper.

3. Protect the paper sheet

Under high pressure, the felt plays a role of buffering and supporting, protecting the paper sheet from direct mechanical damage and reducing the damage and defects of the paper sheet.

4. Improve the surface quality of the paper

The smoothness of the press felt surface directly affects the flatness and smoothness of the paper surface, thereby improving the final quality of the paper.

5. Guide the paper sheet

The felt also plays the role of transporting the paper sheet in the paper machine, ensuring that the paper sheet passes smoothly through the press section without deviation or wrinkles.

Press Felt Categories

According to application requirements and structural characteristics, Press Felt can be divided into the following categories:

1. Classification by number of layers: 

Single Layer Press Felt

• Features: It is composed of one layer of base fabric, suitable for low-speed paper machines and general paper production.

• Advantages: Simple structure and relatively low price.

• Use: Mainly used for paper production with low air permeability requirements, such as corrugated paper.

Double Layer Press Felt

• Features: It is interwoven with two layers of base fabric, with higher strength and better stability.

• Advantages: Excellent drainage performance, suitable for medium and high-speed paper machines.

• Use: Suitable for production processes such as newsprint and writing paper.

Triple Layer Press Felt

• Features: It is composed of three layers of base fabric or two layers of base fabric and one layer of fiber layer, with complex structure and better performance.

• Advantages: Strong pressure resistance, long service life, suitable for high-speed paper machines.

• Use: Widely used in high-quality paper (such as coated paper, cultural paper) and high-speed paper machines.

2. Classification by production process

Woven Press Felt

• Features: The base fabric is woven and the surface is needle-punched.

• Advantages: Uniform thickness, good air permeability, and high strength.

• Uses: Suitable for most types of paper production.

Needle Press Felt

• Features: Made of non-woven needle-punched technology, the surface is softer.

• Advantages: The surface is flat and has good water absorption, which can achieve high-quality production of fine paper.

• Uses: Suitable for the production of paper that requires high flatness and smoothness, such as coated paper.

3. Classification by function

Water Absorption Felt

• Features: The focus is on rapid water absorption and drainage to improve paper web dewatering efficiency.

• Application: Used to produce paper with high water absorption requirements, such as toilet paper.

Wear Resistance Felt

• Features: Designed for high pressure and long-term operation, with excellent wear resistance.

• Application: Used in high-load pressing areas of high-speed paper machines.

Press Felt Structure

The structure of Press Felt is a key consumable used in the press section of a paper machine, mainly used to support paper dehydration and transmit mechanical pressing force. Its structure generally includes the following parts:

Base Fabric

• Provides strength and stability to support the entire blanket.

• Allows moisture to penetrate and drain quickly.

Batt Layer

• Directly contacts the paper sheet, absorbs and transports moisture.

• Provides surface support for the paper sheet to prevent damage to the paper sheet during pressing.

Functional Layer

• Enhances the permeability and dehydration performance of the blanket.

• Improve the surface properties of the blanket, such as improving compression resistance and wear resistance.

Features of Press Felt

Press Felt is one of the key components of the press section of a paper machine. Its main functions and features are as follows:

Press Felt Production Process

1. Raw material selection:

• Fiber selection: According to the requirements, appropriate natural fibers (such as wool, cotton) and synthetic fibers (such as polyester, polypropylene) are selected as basic raw materials.

• Fiber preparation: These fibers are cut into lengths suitable for weaving and cleaned as necessary to remove impurities.

2. Fiber weaving/needling:

• Weaving: Some Press felts are made by weaving, which interweaves fibers to form cloth. This method can provide better air permeability and uniform structure.

• Needling: More Press felts are made by needling, in which the fibers are pierced and fixed to a layer of base cloth to increase density and stability. This method is suitable for the needs of enhancing wear resistance and extending service life.

3. Finishing and reinforcement:

• After weaving or needling, Press felt is usually compressed and reinforced to improve its tensile and wear resistance.

• Coating may be used to improve water resistance or heat resistance, or the surface may be chemically treated to enhance its performance.

4. Forming and heat treatment:

• The surface of the press felt will be formed by heat pressing and other methods to ensure that it has the required thickness, density and structural characteristics.

• High temperature treatment can also improve the high temperature resistance of the press felt to ensure that it will not deform or degrade during the papermaking process.

5. Quality inspection and testing:

• After production, the press felt is subjected to a series of quality inspections, including tests on wear resistance, air permeability, tensile strength, thickness, etc. to ensure that it meets the use standards.

Application areas of Press Felt

1. Papermaking industry

Water absorption and pressing: used in the pressing section of papermaking machines to help dehydrate paper, improve drying efficiency and paper quality.

2. Textile industry

Used in the process of manufacturing certain special fabrics that require dehydration and pressing.

3. Nonwoven fabric industry

Used to provide stable pressing and molding support when manufacturing nonwoven fabrics to ensure the quality of the finished product.

4. Leather industry

Used for dehydration and flattening of wet leather during leather processing.

5. Other application areas

Chemical industry: Used for dehydration and filtration in certain chemical production processes.

Food processing: Used in the production of paper packaging materials or special dehydration processes.

Selection and maintenance of Press Felt

Selection of Press Felt

Paper machine type and operating conditions

• Operating speed: High-speed paper machines require blankets with high air permeability and wear resistance.

• Pressing configuration: Different types of presses (such as single press, double press or large roller diameter press) require appropriate blanket structures.

Paper type and quality requirements

• Different paper types (such as newsprint, cultural paper, corrugated base paper, etc.) have different requirements for the air permeability, compressibility and surface flatness of blankets.

• High-grade paper types require high-quality blankets to ensure surface smoothness and uniform moisture distribution.

Material and structure of blankets

• Fiber material: High-strength polyester fiber is usually selected, which has good wear resistance and chemical stability.

• Structural design: Single-layer, double-layer or multi-layer blankets are selected according to dehydration efficiency and compressibility requirements; reinforced structures are suitable for higher pressure applications.

Maintenance of Press Felt

Regular cleaning

• Use high-pressure water, chemical cleaning agents or ultrasonic cleaning equipment to remove fiber, filler and resin residues on the felt.

• According to the running time of the paper machine, set the cleaning cycle reasonably to avoid clogging of the felt and affect the air permeability and dehydration performance.

Tension adjustment

• Ensure that the tension of the felt is uniform and moderate to prevent stretch damage caused by excessive tension or wrinkles caused by too low tension.

Check for wear and damage

• Regularly check the edges and surfaces of the felt for wear, tear or hardening, and replace them in time if necessary.

• Use a felt status monitoring device (such as an infrared scanner) to detect abnormal areas during operation.

Latest technologies and future trends

Latest Technology:

• Multi-layer structure design: Modern press felt adopts a multi-layer structure, such as a double or triple layer design, to improve its durability and moisture removal efficiency. For example, press felt with a three-layer base cloth has been used in the market.

• High-performance materials: Use high-strength, wear-resistant synthetic fibers such as polyamide (nylon) and polyester to replace traditional wool materials to improve the service life and performance of felt.

• Surface treatment technology: Through special surface treatments such as coating or chemical treatment, the felt's anti-pollution ability is enhanced, the contamination of impurities in the pulp to the felt is reduced, and its service life is extended.

• Intelligent monitoring system: Integrated sensors and monitoring systems monitor the status and performance of the felt in real time, detect problems in time, and optimize the production process.

Future trends:

• Environmental protection and sustainability: With increasingly stringent environmental regulations, future press felts will pay more attention to sustainability, use recyclable and environmentally friendly materials, and reduce the impact on the environment.

• High efficiency and energy saving: With the increase in paper machine speed, the performance requirements for felts are also higher. The future felts will focus on improving moisture removal efficiency, reducing energy consumption, and meeting the needs of efficient production.

• Customization and intelligence: Provide customized felt solutions according to different paper types and production processes. At the same time, intelligent felts will be combined with the automation system of the production line to achieve more precise control and optimization.

• Digitalization and data analysis: Through digital technology, collect and analyze the operation data of felts, provide decision support, optimize the production process, and improve product quality.

Conclusion

In the papermaking industry, Press Felt plays a vital role. It is not only an indispensable part of the paper production process, but also directly affects the quality and production efficiency of paper. As a key component of the paper machine, Press Felt is responsible for carrying moisture and pressure during the dehydration process, thereby ensuring the uniformity, smoothness and strength of the paper. Since it is directly involved in the dehydration and forming of pulp, choosing high-quality Press Felt and doing daily maintenance are crucial to the long-term stable operation of the production line.

KEYLIFE is a trusted brand in China's papermaking machine material industry. We produce high-quality press felts in accordance with international quality standards. At present, our press felts have been sold to many countries and regions around the world.

If you need our press felts, please contact our sales team. They will provide reasonable quotations and product information!

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