How to Choose the Right Extruder for PVC Pipes

Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with nearly 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.

When it comes to PVC pipe production, selecting the right extruder is critical to achieving consistent quality, high output, and long-term reliability. Among the most widely used options are intermeshing counter-rotating conical twin-screw extruders, which are ideal for manufacturing PVC pipes, profiles, and sheets. Intermeshing counter-rotating parallel twin-screw extruders are commonly used for PVC pelletizing and profile extrusion. Meanwhile, intermeshing co-rotating parallel twin-screw extruders feature modular screw and barrel designs, allowing screw elements to be configured according to specific formulation and process requirements. These offer excellent mixing performance, high operating speeds, large conveying capacity, and self-cleaning capabilities, making them particularly suitable for filling modification, blending modification, reinforcement modification, and reactive extrusion.

Key Advantages of Intermeshing Counter-Rotating Conical Twin-Screw Extruders for PVC-U Pipe Production

(1) Positive Displacement Conveying Mechanism

The intermeshing screw channels of a counter-rotating conical twin-screw extruder can be visualized as forming laterally enclosed "C-shaped" chambers. When PVC dry blend is fed into the larger-volume screw channels of the feed section, the channels are not completely filled, yet the material is enclosed within a series of these "C-shaped" chambers. As a result, the material is conveyed by positive displacement as the screws rotate. This effectively prevents wall slip and avoids PVC resin degradation caused by excessive residence time.

(2) Excellent Plasticization Quality

On one hand, the volume of the "C-shaped" chambers gradually decreases from the first chamber in the feed section to the last chamber in the metering section. This progressive reduction promotes compression, conveying, and melting of the PVC compound, while also facilitating devolatilization. On the other hand, the "C-shaped" chambers are not completely sealed from one another—there is a certain clearance in the kneading zone. This accelerates mixing and plasticization, resulting in improved plasticization quality.

(3) Low Frictional and Shear Heat Generation, Preventing PVC Resin Degradation

First, the large screw diameter in the feed section creates a large screw channel volume and increases the screw surface area, which benefits heat absorption, melting, and plasticization of the material. Second, because the screw diameter gradually decreases, the peripheral screw speed decreases gently along the axial direction. This results in a smaller temperature difference between the material and the screw, generating less frictional and shear heat, which helps prevent PVC resin from degrading.

If you need more information, Ningbo Fangli Technology Co., Ltd. welcomes you to contact for a detailed inquiry, we will provide you with professional technical guidance or equipment procurement suggestions.