Choosing an extruder comes down to three questions: what material goes in, what product comes out, and how much output you need. The screw type answers most of it.
Single screw extruder
A single screw conveys and melts the material along one flighted screw. It is the standard choice for pelletised materials such as HDPE, PP and PE, and for pipe, sheet and film where the melt is fed as granules. The mechanical design is simple, there are fewer wearing parts and maintenance is straightforward, with stable output on one material. It is the base unit of most HDPE pipe lines and of sheet and film lines.
Conical twin screw extruder
Two conical screws, larger at the feed end and smaller at the discharge end. This geometry gives a large feed volume for powder and dry blend, with controlled shear and heat build-up as the material is compressed. That is why conical twin screw extruders are the common choice for PVC pipe and PVC profile, where the raw material is a dry blend of powder, stabiliser and filler. The positive conveying action handles powder better than a single screw.
Parallel twin screw extruder
Two screws of equal diameter running side by side. Because the barrels are cylindrical, a longer length-to-diameter ratio is possible, which gives higher output and stronger mixing. Parallel twin screw extruders are used for PVC pipe, profile and WPC, and where more output is needed on the same footprint.
How to choose
- Material form. Powder or dry blend (PVC) points to a twin screw extruder. Pellets (HDPE, PP, PE) point to a single screw extruder.
- Product. HDPE and PP pipe, sheet and film: single screw. PVC pipe and profile, WPC: conical or parallel twin screw.
- Output. The same product can be produced on different models. The screw type and the extruder size set the output range – compare the capacity figures of each model, not only the motor power.
- Downstream. The extruder is only the first unit of the line. Die head, calibration, haul-off and cutter decide the final pipe or profile quality.
- Maintenance and spares. A single screw extruder has the fewest wearing parts. Twin screw extruders need more attention on screw and barrel clearances.
Summary
PVC dry blend → conical or parallel twin screw. HDPE / PP / PE pellets, sheet and film → single screw. Where the highest output on PVC is required, parallel twin screw; where powder feeding and stable quality matter more, conical twin screw.
Winone Tech designs and manufactures all three types, together with the matching die heads and downstream equipment. Tell us the material and the product, and we will recommend the screw type and the line configuration. Contact us for a quotation.