How to Choose Suitable Press Felt

According to The Technical Conditions of Paper Machine Production

A.Line Pressure and Mechanical Load

The line pressure and mechanical load in the paper press area are directly proportional to the strength requirements of the press felt. The greater the line pressure, the higher the compressive strength that the selected paper making felt can withstand during its lifecycle. At the same time, it is required that the paper making felt has good elastic recovery performance, so as to maintain good water filtration performance and water holding space for a long time. The greater the mechanical load, the greater the elastic recovery of the bottom mesh layer of the paper making felt and the tensile (fracture) strength it has when transmitting power, while requiring its elongation and shrinkage rates to be small. Generally, press felt manufacturers will design bottom mesh with different organizational structures based on the pressure and mechanical load of different paper machine pressing lines to meet the needs of different line pressures and mechanical loads.

B.The Magnitude of Vacuum Degree

The vacuum degree of the paper making system and the setting state of the vacuum system directly determine the moisture content, cleanliness, and dewatering performance of the paper making felt, especially the bottom press felt. If the vacuum is too small, it will cause problems such as poor water dragging on wet paper sheets, high moisture content in felts, inability to apply pressure in the pressure zone, difficulty in pick up paper, and inability to clean felts thoroughly. Excessive vacuum will lead to increased transmission load on the paper machine, increased wear on the surface of felt, and energy waste.

C. Washing Conditions

The washing conditions include the configuration of the washing device, the requirements for washing water quality, the setting of washing water pressure and vacuum degree, etc. The quality of washing conditions is directly proportional to the washing effect. Under normal circumstances, it is required that each paper machine should have good washing conditions to meet the requirements of the forming fabric and press felt, but in reality, the situation of each paper machine is different, and the situation of each paper machine is also different at different times. Therefore, when choosing paper making felts, it is necessary to adjust the variety, quantity, structural ratio, production process, and degree of shaping of the paper making felts within a certain range to meet the needs of the paper machine.

D. Pulp Situation

The quality of the pulp not only affects the quality of the paper , but also plays a crucial role in the filtration status and service life of the felt. The beating degree of the pulp, the viscosity of the filler, and the content of impurities are inversely proportional to the water filtration performance of the felt. In addition, the chemical fiber is resistant to weak alkali and acid, and the pH value of the pulp also has a certain impact on the felt. When selecting a matching paper making felt, it is important to pay attention to parameters such as the ratio of the pulp, the degree of beating and wet weight of the pulp, the use of chemical products, and the acidity and alkalinity of the pulp. These directly affect the water filtration performance and service life of the paper making felt, as well as its surface viscosity state.

E. Dehydration Method

The pressing form of the paper machine determines the dehydration method of wet paper sheets. In general, paper machines that mainly use horizontal dehydration should choose press felt with high compressibility and small weight; A paper machine that combines press dewatering and vacuum suction for vertical dewatering generally selects press felt with low compressibility, good elasticity, and large weight.

Choose Based on The Previous Use of Press Felt

For a normally operating paper machine, when selecting a new paper making felt, it is necessary to refer to the previous use of paper making felt and make improvements. Only in this way can the correct selection be made in terms of the variety, quantity, breathability, thickness, and other special requirements of the press felt, so that the re selected paper making felt can better meet the needs of the paper machine and prevent production abnormalities caused by improper selection of the press felt.

Communicate with Technical Personnel from Press Felt Suppliers

With the continuous improvement of paper making technology, the requirements for the performance of paper making felts that match it are also increasing. Therefore, the performance of paper making felts is becoming more refined and the variety is becoming more and more diverse. Moreover, there are many factors that need to be adjusted in the production of paper making felts, which undoubtedly brings a lot of trouble to the engineering and technical personnel of paper mills when choosing press felt. Regular technical exchanges with felt suppliers' technicians are a great way to truly achieve that paper making felts are designed next to paper machines.