Show You More Details About Polyester Forming Fabric Wear Informations

Why Polyester Forming Fabric Wear Matters

Throughout the papermaking process, the forming section is a critical stage influencing paper quality. Mechanical wear is a primary factor affecting the performance of polyester forming fabrics, and can even cause the premature removal.

As the equipment operates over time, the forming fabric gradually wears its filaments due to prolonged contact and friction with components such as dewatering elements, vacuum boxes, and rolls, resulting in a continuous reduction in the fabric's thickness.

When the wear of a polyester forming fabric reaches its limit, its dewatering performance deteriorates significantly, easily leading to poor drainage and various paper defects caused by compromised sheet formation quality.

Therefore, understanding the types of wear and their causes helps you detect issues early and extend the service life of polyester forming fabrics.

Typical Signs of Wear on Polyester Forming Fabrics

After undergoing mechanical wear, the surface of the filaments in a polyester forming fabric typically develops burrs oriented in various directions.

Based on the location and orientation of the burrs, the wear on polyester forming fabrics can be categorized into three types, each corresponding to a specific operating condition of the equipment. Therefore, you can determine the source of the wear by observing the wear type, specifically, the location and orientation of the burrs.

Polyester Forming Fabric Trailing Wear

Trailing wear is the most common form of polyester forming fabric mechanical wear. It occurs when the running speed of the forming fabric exceeds the surface speed of the dewatering elements and other devices in contact.

This type of wear typically occurs at stationary dewatering elements, such as dewatering forming boards and vacuum box covers. Because these components remain relatively stationary, the polyester forming fabric continuously rubs against them, eventually creating burrs on the trailing edge (relative to the running direction), which are known as "drag burrs."

Therefore, the material, surface roughness, and wear condition of the dewatering forming board and vacuum box covers directly affect the wear resistance of the forming fabric.

Polyester Forming Fabric Leading Wear 

Leading wear is caused by the running speed of the polyester forming fabric being lower than the surface speed of the dewatering elements and other devices that are in contact.

This type of wear typically occurs near rotating components such as breast rolls and drive rolls. When the linear speed of the roll surface exceeds the fabric speed, the direction of friction changes, causing burrs to form on the leading side of the polyester forming fabric strands relative to the direction of travel.

Polyester Forming Fabric Lateral Wear

Lateral wear primarily occurs along the weft direction of polyester forming fabrics, and its formation is closely related to uneven CD loading on the paper machine.

For example, excessive tension on the forming fabric or overly strong suction at the vacuum gap can cause localized bending or deformation of the fabric, resulting in transverse wear of the weft yarns.

Additionally, inadequate installation precision or abnormal operating conditions in the forming section can also lead to uneven transverse wear.

Assessment of Polyester Forming Fabric Wear Level

The simplest method to determine the degree of wear on a polyester forming fabric is to measure the thickness of the fabric itself.

You can determine the rate of thickness reduction by using a micrometer to measure the thickness of the polyester forming fabric at multiple locations, calculating the average value, and comparing it with the original thickness recorded when the new fabric was installed.

You can use the following formula to calculate the polyester forming fabric thickness reduction rate:

Thickness Reduction (%) = (T₀ − T₁) / T₀ × 100

• T₀ = Original fabric thickness

• T₁ = Remaining fabric thickness

In general, you can refer to the following replacement criteria.

• Single-layer forming fabrics: 25–35% thickness reduction

• Multi-layer forming fabrics: 20–25% thickness reduction

It should be noted that the rate of thickness reduction is merely one important reference indicator for assessing the service life of the polyester forming fabric. 

The actual replacement timing should be determined through a comprehensive evaluation that also considers factors such as dewatering performance, paper quality, and the operational stability of the paper machine.