PAPTEX DLH 2.5-Layer Forming Fabric

Engineering Overview

PAPTEX DLH 2.5-Layer Forming Fabric is an upgraded double-layer design with an additional support weft layer. It bridges the gap between standard double-layer fabrics and full SSB triple-layer fabrics by improving cross-direction stability and fibre support without the weight and cost of a complete triple-layer construction.

Product Definition

The fabric combines a fine paper-side layer, a durable machine-side layer and an intermediate support weft layer. The support weft improves CD dimensional stability, shares machine-side wear and helps maintain uniform sheet formation across the width of the machine.

Why Choose This Construction

DLH is suited to mills that need a practical performance upgrade from conventional double-layer forming fabric. It offers stronger stability, improved fibre support and a typical 15-25% longer running life than a standard double-layer fabric, while remaining a cost-effective option below a full SSB design.

Typical Applications

Designed for the forming section of packaging, kraft, corrugated and board machines. It is particularly suitable for medium to high basis-weight grades between 40 and 400 g/m2 and machine speeds from 400 to 1,200 m/min.

Technical Design

Operating Principle

The fine PET paper-side weave promotes even drainage and fibre retention. The heavier machine-side weave withstands contact with forming-board and drainage elements. Between them, the support weft distributes load, reinforces the cross-machine direction and helps keep the two working layers stable during operation.

Drainage and Sheet Formation

Air permeability is typically 400-650 CFM (6,350-10,300 m3/m2/h). The construction balances controlled micro-drainage at the paper side with efficient water removal through the machine side, supporting stable formation for board and packaging grades.

Wear Performance

The additional support weft shares part of the wear load from the machine-side layer. This produces a more gradual wear pattern and can extend service life by 15-25% compared with a standard double-layer fabric under comparable operating conditions.

Operating Limits

Recommended for machines up to 1,200 m/min, continuous temperatures up to 80 C and a typical pH range of 4-10. For very high-speed machines or low-basis-weight tissue grades, PAPTEX engineers normally recommend a full SSB triple-layer structure.

Installation and Maintenance

Use correct fabric handling equipment and maintain an even running tension of 6-8 kN/m. Start at reduced speed while the fabric seats uniformly, then verify tracking and shower alignment. Maintain continuous needle-shower cleaning at 15-20 bar and use scheduled chemical cleaning appropriate to the machine chemistry. Avoid excessive high-pressure cleaning that could damage the support weft.

Replacement Guidance

Plan replacement when machine-side yarn wear exceeds 35%, exposed support weft exceeds 10% of the surface, permeability rises more than 25% above the original value, sheet marking appears, or CD dimensional deviation exceeds 5 mm. Typical service life is 35-55 days, depending on stock, machine condition and cleaning practice.

Quality and Support

PAPTEX manufactures DLH forming fabrics under ISO 9001 quality controls. Incoming monofilament inspection, warping tension monitoring, weaving inspection, full-width permeability checks and final visual inspection provide traceability from raw material to shipment. Engineering support is available for selection, installation review and running-condition analysis.