How to Solve Paper Making Felt Linting and Abrasive Wear

Paper Making Felt Linting and Wear and Tear

The simplest form of paper making felt lint is when the felt fibers adhere to the surface of the paper. There are many reasons that can cause damage and felt lint of press felt, among which there are two main ones: being scratched by machine components and being damaged by chemicals. The most common situation is that the surface of the press felt is torn loose by excessively high pressure water flow. Sometimes the responsibility does not lie with the press felt, as fibers can also come from pulp or even from external system contaminants.
It is understandable that a small amount of floating linting may fall off during the use of paper making felts, but it is absolutely not allowed to have a large amount of fuzzing and shedding. If abnormal shedding is found during the installation of a new press felt, the design and manufacturing process should be modified to overcome it. If linting falls off throughout the entire usage period, it is likely due to severe mechanical or frictional wear.
After the linting  falls off from the felt, especially from the front, it adheres to the surface of the paper, which directly affects the printing effect of the paper. For the paper types that need to be coated, it can cause the coating doctor blade to get stuck, resulting in uneven coating and ultimately affecting the printing effect.

Reasons and Solutions for Causing Linting and Wear of Paper Making Felts

• The needle tightness of the paper making felt is insufficient and the shaping is too light, resulting in loose fibers that are not tightly held together, making the felt prone to fuzzing and shedding.
  By adopting a reasonable needling process for the felt, increasing the needling depth and number of needling passes appropriately, the needle tightness and shaping degree of the paper making felt can be improved. Hot oil drum shaping, hot air shaping, hot oil drum plus far-infrared shaping, or hot air heated oil drum shaping methods can be used to improve the shaping quality of the paper making felt, thereby enhancing its wear resistance and anti linting removal performance. The use of chemical treatment to improve the bonding strength between felt fibers is a new technology that has been studied abroad for many years, and some felt manufacturers in China have begun to use this technology to develop and research new products.
• There is no lubricating water between the suction water box cover and the felts, resulting in an increase in temperature and fiber damage and linting. For paper machines, especially medium and high-speed ones, the reasonable use of lubricating water is not only beneficial for improving the cleanliness of the paper making felt, but also for creating a water film between the vacuum suction box cover and the felt, which plays a role in lubrication, sealing, and cooling.
• The material of the vacuum suction box cover is not good, with high impurity content or excessive friction coefficient. The edges and seams of the suction box cover have burrs or sharp “knife edges” that have not been rounded. The angle between the vacuum suction box and the paper making felt is too large, and the vacuum degree is too high. The suction box cover is partially uneven or the fixing screws are exposed, causing the felt to wear and fall off. Improper selection of seal material at both ends of the vacuum suction cover seam, improper treatment of seals in vacuum and non vacuum areas, and no lubricating water at the edges can easily lead to excessive edge wear and depilation of the paper making felts.
• The roll surface of the felt roll has burrs, rust marks, and the roller surface is coated with pulp. The rubber thread platform of the felt roll is too high, the thread platform has obvious edges and corners, and there are no edges or corners between the rubber platform and the roller body at the eight shaped opening, or the transition zone between high and low is too short, all of which can easily cause wear and linting loss of the paper making felt.

All felt roll surfaces should be kept smooth and free of burrs and rust marks. It is recommended to use copper coated rollers, stainless steel coated rollers, and rubber coated rollers. The height of the spiral rubber strip of the felt roll is generally 8-15mm, the width of the rubber table is 20-40mm, the rubber table has no edges and corners, and the chamfer should be smooth. The angle of the octagonal opening is generally 600-1200, and the starting point of the octagonal opening should have a clear transition slope.

5. There is a speed difference between the relevant transmission points, which causes the felt to rub and wear, resulting in felt loss. Correctly adjust the speed ratio of each transmission point to avoid abnormal speed differences.

6. Insufficient cleanliness of the pulp, high residual chlorine, and the use of chemicals with high acid and alkali concentrations for washing paper making felts can lead to premature corrosion and aging of the felts, resulting in a decrease in their wear resistance and felt loss.