How to Choose the Right Press Felt for Your Paper Machine

Selecting the best press felt depends on several factors, including the paper type and basis weight being produced, machine speed, surface-finish requirements, paper machine type, operating conditions, and available felt-cleaning equipment.

When designing and selecting paper machine felts, pay close attention to the paper machine’s relevant production technical parameters.

Only by appropriately adjusting the relevant process and technical parameters of the paper machine press felt based on the actual operating conditions of the paper machine can the press felt more effectively meet your practical needs.

Line Pressure and Mechanical Load

The line pressure and mechanical load in the press section of a paper machine are directly proportional to the strength requirements of the press felt.

Higher Line Pressure Requires Greater Compression Resistance 

The greater the line pressure, the higher the compressive strength the selected press felt must possess throughout its service life. At the same time, the paper-making felt must have good elastic recovery properties to ensure the felt maintains good dewatering performance and water-holding capacity over the long term.

Mechanical Load and Press Felt Strength

As the mechanical load on paper machines increases, higher demands are placed on the elastic recovery and tensile strength of the base layer of press felts. At the same time, they must also maintain low elongation and shrinkage rates.

Vacuum Level

The vacuum level of the paper machine system and the configuration of the vacuum system directly affect various properties of the paper-making press felt, particularly the bottom wire felt, including moisture content, cleanliness, and dewatering performance.

Problems Caused by Low Vacuum

If the vacuum level is too low, it can result in insufficient dewatering of the wet paper sheet and excessively high moisture content in the press felt, leading to problems such as difficulty in increasing pressure in the press section, difficulty in feeding the paper, and incomplete cleaning of the press felt.

Problems Caused by Excessive Vacuum

If the vacuum level in the paper machine is too high, it will lead to increased drive loads on the paper machine, accelerated wear on the press felt, and energy waste, among other problems.

Press Felt Cleaning Conditions

Press felt washing conditions include the configuration of the washing equipment, water quality requirements, and the settings for water pressure and vacuum level. The quality of the washing conditions is directly proportional to the effectiveness of the washing process.

When selecting the press felt, it is essential to consider the washing conditions of your paper machine.

Under normal circumstances, each paper machine is required to have optimal washing conditions to meet the requirements of the press felt. However, in reality, the conditions vary from machine to machine, and they also differ from one period to another for each machine.

Therefore, within a certain range, the type, basis weight, structural proportions, manufacturing process, and degree of setting of the paper-making press felt should be appropriately selected and adjusted based on the actual operating requirements of the paper machine.

Pulp Conditions

The quality of the pulp affects the quality of the paper being produced and plays a crucial role in the dewatering performance and service life of the press felt.

When selecting the appropriate paper-making press felt, it is essential to consider parameters including pulp composition, pulp refining degree, wet weight, the use of chemical additives, and pulp pH. These factors directly affect the press felt’s dewatering performance and service life, as well as the degree of pulp adhesion to its surface.

Dewatering Method

The type of press used in a paper machine determines how the wet paper sheet is dewatered, and different press types require different paper machine press felts.

Generally speaking, for paper machines that rely primarily on horizontal dewatering, it is advisable to select the press felt with high compressibility and low basis weight.

For paper machines employing both press dewatering and vacuum suction for vertical dewatering, a press felt with low compressibility, good elasticity, and high basis weight should be selected.

The number of layers in the bottom of the press felt should also be determined based on the parameters of the press section of the paper machine described above.