Application and Precautions of Paper Machine Dryer Fabric in the Drying Section

The paper machine dryer fabric is mainly applied in the drying section of a paper machine. Its primary function is to convey the wet paper web and facilitate the drying process of the paper through the front group of dryer cylinders during transportation.

Types and Applications of Dryer Fabrics

Double-warp flat filament dryer fabrics, characterized by high fabric strength, excellent air permeability and high drying efficiency, are more widely used in the production of ordinary wrapping paper where there are no stringent requirements for the surface properties of the paper.

Spiral dryer fabrics feature stain resistance, nearly seamless construction, high wear resistance and easy cleanability; however, their drawback is that they leave distinct mesh marks on the paper surface.

Materials of Dryer Fabrics The predominant material used in modern dryer fabrics is polyester monofilament, which is categorized into round filaments and flat filaments. Consequently, the woven fabrics are divided into round filament dryer fabrics and flat filament dryer fabrics. According to customer application feedback, flat filament dryer fabrics outperform round filament alternatives. Flat filaments enable more comprehensive contact with the paper web, reducing the likelihood of mesh mark formation. Additionally, they facilitate easier removal of adhesive contaminants adhering to the fabric surface.

Key Properties of Dryer Fabrics

1. Pollution Resistance

In addition to minimizing fabric fouling through the geometric design of filaments, the adhesion of sticky substances can be reduced by incorporating fluorine-based additives into the polyester material to lower its surface energy. This inhibits contaminants from adhering to the fabric surface, thereby significantly reducing the occurrence of paper defects such as sticky black specks caused by dirt accumulation on the dryer fabric, insufficient drying capacity due to decreased air permeability, uneven moisture distribution across the paper machine width, and black spots.

2. Hydrolysis Resistance

Dryer fabrics operate inside closed hoods under severe high-temperature and high-humidity conditions. Moreover, the pH value of some base paper is non-neutral, which results in severe corrosion of the polyester material. For most dryer fabrics, the end of their service life is not caused by wear (unlike forming fabrics and press felts, dryer fabrics undergo almost entirely rolling friction), but by hydrolysis due to fouling or corrosion. To mitigate hydrolysis risks, anti-hydrolysis agents are typically added to the dryer fabric filaments to alleviate this tendency.

Precautions for Dryer Fabric Usage

• The seam joint is the weakest point in terms of the dryer fabric’s strength. Therefore, strict attention should be paid to the strength of the stitching thread and the operational procedures for fabric joining.

• The seam joint is also the area most prone to causing dryer fabric marks on the paper surface. In addition to selecting an alternative seam type, reducing the dryer fabric tension, minimizing the large wrap angle of the fabric, and optimizing the path to avoid sharp bends can effectively prevent such issues.

• The edges of the dryer fabric are repeatedly subjected to collisions with the guide rolls and correctors. If the edge weaving is defective or hydrolysis occurs, edge fraying is likely to happen. A thorough inspection of the fabric edges should be conducted during each machine shutdown.

• Production personnel often assume that dryer fabrics of the same or similar length can be interchanged arbitrarily. It should be noted that manufacturers usually customize the dryer fabric design to match specific operating conditions. For instance, dryer fabrics used in high-evaporation sections are often engineered with enhanced hydrolysis resistance. Therefore, unless spare parts are in short supply, it is not advisable to randomly alter the installation positions of dryer fabrics.