Drilled Hole Screen Basket
This type of drilled hole screen basket features a circular through-hole design. Its common hole diameters range from φ1.2 to 2.5 mm, with the screen holes featuring a straight-through cylindrical structure.
For this type of pressure screen basket, if the fibers being processed are long and thin, they need to be oriented in the correct direction to pass through the holes. Therefore, long strips of adhesive and plastic filaments, among other impurities, can easily get stuck laterally inside the drilled screen basket holes. This can block the holes and even cause the screen basket to clog.
Advantage
With a high open area ratio (25-30%), the drilled hole screen basket can handle more slurry while maintaining the same screen drum area. It is robust, resists impact from large impurities, and is not easily deformed or damaged.
Shortcoming
Circular holes have a weak ability to intercept long strips of adhesive. Impurities can easily become trapped inside the holes and cannot be effectively removed by the negative pressure generated by the rotor. As operation continues, clogging becomes increasingly severe, requiring a large amount of additional dilution water to flush the screen basket surface.
Slotted Screen Basket
The slotted screen basket is composed of multiple V-shaped wedge bars, forming a continuous long strip of screen slots. The screen slots feature a V-shaped profile that is narrower at the outside and wider toward the inside. In the flow section, the commonly used slot width for the slotted screen basket is around 0.20 to 0.35 mm.
Advantages of V-Shaped Cross Section
As long as impurities squeeze through the slots on the surface of the slotted screen basket, the internal space increases, preventing them from getting stuck inside the slots and making it less likely to clog the basket.
Shortcoming
Low open area (7–12%), resulting in lower pulp throughput than drilled hole screen baskets with the same screening area.
The processing cost of the slotted screen basket is higher, and large hard objects can easily damage and deform the screen slots.
Actual Operating Performance of Drilled Hole vs. Slotted Screen Baskets
| Comparison Item | Perforated Screen (φ1.8 mm Hole Diameter) | Slotted Screen (0.25 mm Slot Width) |
| Pulp Throughput at the Same Effective Screening Area | 100% baseline | 60–70% (reduced capacity) |
| Long Sticky and Plastic Contaminant Removal Rate | 45‑55% | 80‑88% |
| Screen Basket Clogging Cycle | Differential pressure starts to rise after 7–10 days | Significant increase occurs after 25–35 days |
| Normal Inlet-to-Outlet Differential Pressure | 20‑35kPa | 25‑40kPa |
| Sticky Contaminant Dirt Count on Paper Surface | 120–160 points/m² | 40‑70 points /m² |
| Dilution Water Consumption per Ton of Pulp | 8- 12 m³ | 3- 5 m³ (significantly less dilution water required) |
| Average Screen Basket Service Life | 6–8 months | 4–6 months. Slot openings are more susceptible to damage from hard contaminants |
How To Select The Pressure Screen Basket
When Is a Drilled Hole Screen Basket Suitable
Suitable for slurries with a high amount of impurities, mainly particulate/fragmented impurities. Moderate requirements for dust levels.
Drawbacks: Less effective at removing hot-melt adhesives and plastic strands, requiring more frequent screen cleaning and higher dilution water consumption.
When Is a Slotted Screen Basket Suitable
OCC waste paper pulp, adhesives, and plastic filaments are abundant.
High requirements for controlling paper spots and paper breaks.
Accept slightly lower pulp throughput and some fiber loss in the reject stream, while using a second-stage screen to recover usable fibers.
Drawback: Large hard contaminants entering the screening chamber can easily deform the screen bars. Proper control of high-consistency cleaning and coarse screening is therefore essential.
