Single Screw vs. Conical Twin Screw Extruders: A Buyer's Comparison Guide

Choosing a plastic extrusion machine usually starts with the extruder itself. JKS Machinery supplies both SJ series single screw plastic extruders and SJSZ series conical twin screw plastic extruders, so buyers can compare the two platforms on machine specifications rather than general claims. This guide explains what each screw type is designed to process, how the JKS model ranges differ, and which JKS full-line configurations are commonly built around a single screw or a conical twin screw extruder.

Wuxi JKS Machinery Manufacturing Co. Ltd., founded in 2013, specializes in custom plastic extrusion machinery and complete turnkey production lines. Its main product range includes plastic sheet, SPC flooring, WPC foam board, plastic pipe, PVC/WPC profile, plastic rod, and waste plastic recycling pelletizing lines, as well as standalone single screw and conical twin screw extruders.

The Selection Problem: Which Screw Architecture Should You Put at the Center of the Line?

The extruder is the core of any plastic extrusion line. It melts, plasticizes, and pushes the material through the die. The screw design affects mixing, shear, output stability, and the type of raw material that can be processed efficiently. A buyer cannot choose an extruder only by motor power or price. The first question is whether the screw configuration matches the raw material form and the finished product type.

JKS documents two distinct platforms:

• The SJ series single screw plastic extruder is described as a versatile unit for thermoplastics such as PVC, PP, PE, Nylon, and ABS.
• The SJSZ series conical twin screw plastic extruder is described as a unit for direct extrusion of PVC powder into pipes, sheets, bars, profiles, and other plastic products.

Industry Background: Why Screw Type Is Central in Today's Market

The broader extrusion machinery market helps explain why buyers need a clear selection logic. According to Grand View Research, the global plastic extrusion machinery market was valued at approximately USD 8.93 billion in 2024 and is projected to reach USD 11.58 billion by 2030. Single-screw extrusion machines held a dominant market share of approximately 62.7% in 2024. Asia Pacific dominated the market in 2024 with a 41.5% revenue share, with China as the leading contributor.

Those numbers show that single screw extruders are widely used across general thermoplastic processing. Conical twin screw extruders are a specialized but important segment, especially for PVC powder processors who want direct extrusion without first preparing pellets.

Detailed Solution 1: JKS SJ Series Single Screw Plastic Extruder

The JKS SJ series includes customized models such as SJ30, SJ45, SJ65, and SJ90. The screw and barrel are made of 38CrMoAlA nitrided alloy steel, and the machine frame is made of Q235 carbon steel. It is designed to process thermoplastics such as PVC, PP, PE, Nylon, and ABS.

With different molds and auxiliary equipment, the same single screw platform can be used to produce pipes, rods, films, pellets, coated products, blow-molded bottles, and other thermoplastic products or semi-finished products. This is why JKS refers to the SJ series as versatile and suitable for various thermoplastic processing needs.

Documented JKS Single Screw Full-Line Examples

• Multi-material Plastic Profile Extrusion Line: Models SJ45, SJ50, and SJ65 process PP, PE, PVC, PS, PC, and ABS. Custom molds can produce imitation marble profile, ceiling panel, door and window small profile, sealing strip, edge band, PC lamp profile, and PVC waterstop. The full line is: feeding system, single screw extruder, calibrating table, cooling tank, haul-off, and fixed-length cutting.
• Solid Plastic Rod Extrusion Line: Models SJ45 and SJ65 process PP, PE, PA, and POM. SJ45 has a screw diameter of 45 mm, L/D 28:1, power 7.5 kW, rod diameter 6–60 mm, and output 5–18 kg/h. SJ65 has a screw diameter of 65 mm, L/D 30:1, power 18.5 kW, rod diameter 30–200 mm, and output 20–60 kg/h.
• PP Hollow Construction Formwork Extrusion Line: JKS lists SJ-90×33 (75 kW) and SJ-130×33 (160 kW) for PP recycled granule processing. Line output is 180–250 kg/h for the SJ90 model and 500–600 kg/h for the SJ130 model. Finished board width is 1220 mm with thickness 15–20 mm.

Detailed Solution 2: JKS SJSZ Series Conical Twin Screw Plastic Extruder

The JKS SJSZ series includes model designations SJSZ-45, SJSZ-51, SJSZ-55, SJSZ-65, SJSZ-80, SJSZ-92, and SJSZ-110. The screw and barrel are made of 38CrMoAlA nitrided alloy steel, and the machine frame is made of Q235 carbon steel.

JKS describes the conical twin screw design with these features: uniform plasticizing and mixing, low shearing, high productivity, stable quality, and long service life. Its main application is direct extrusion of PVC powder for pipes, sheets, bars, profiles, and other plastic products. This design is also used in JKS full lines for WPC door and flooring products.

SJSZ Standalone Extruder Output Range

Step-by-Step Breakdown: How to Choose Between SJ and SJSZ

Use the following logic as a starting point. A final line recommendation should always be discussed with the extruder manufacturer because the screw type, die, downstream equipment, and product dimensions must fit together.

1. Identify your raw material form. If you plan to extrude PVC powder directly, the JKS SJSZ conical twin screw platform is documented for that application. If you plan to process general thermoplastic materials such as PP, PE, Nylon, ABS, or PVC in a form suitable for a general extruder, the SJ single screw platform is documented for those materials.
2. Define the finished product geometry. Single screw JKS lines are documented for rods, multi-material profiles, films, pellets, coated products, and blow-molded bottles. Conical twin screw JKS lines are documented for PVC pipes, sheets, bars, profiles, WPC door panels, foam boards, hollow wall panels, and PVC pelletizing.
3. Estimate your output requirement. The SJSZ standalone models give clear output ratings from 70 kg/h to 1000 kg/h. For full single screw lines, JKS documents line-level outputs such as 180–250 kg/h, 500–600 kg/h, and 20–60 kg/h depending on product type and downstream configuration.
4. Check full-line rated capacity. In JKS pipe lines, the extruder and downstream equipment are rated together. For example, the PVC63 pipe line uses the SJSZ65/132 conical twin screw extruder and produces 270 kg/h; the PVC250 line uses SJSZ80/156, and the PVC630 line uses SJSZ92/188.
5. Request the manufacturer to map your material formula and product specification to a specific line. Because JKS builds custom full-set production lines, the actual screw configuration should be confirmed together with the die, calibration unit, cooling tank, haul-off, and cutting equipment.

Use Cases: Where Each JKS Screw Platform Is Applied

Use Case 1: PVC Water Supply and Drainage Pipe Production

JKS PVC water supply and drainage pipe extrusion lines are built around conical twin screw extruders. Models include PVC63, PVC250, and PVC630. PVC63 handles pipe diameters from Φ16 mm to Φ63 mm using SJSZ65/132 with 37 kW main motor power and a rated output of 270 kg/h. PVC250 handles Φ90–Φ250 mm using SJSZ80/156 with 55 kW and 450 kg/h. PVC630 handles Φ315–Φ630 mm using SJSZ92/188 with 110 kW and 800 kg/h. These lines process PVC+CaCO₃ and are equipped with vacuum calibration, multi-claw traction, and dust-free cutting.

Use Case 2: WPC Door Panels and PVC/WPC Foam Boards

SJSZ conical twin screw extruders also appear in JKS board production lines. The WPC door panel extrusion line is available in SJSZ80 and SJSZ92 configurations, with output capacities of 250–400 kg/h and 400–600 kg/h respectively. The PVC & WPC foam board extrusion line, model SJSZ80/156, uses a 75 kW main motor and produces 400–500 kg/h with a finished board width of 1220 mm.

Use Case 3: Flexible Multi-Material Profile and Engineering Rod Production

When the product mix is more varied, a single screw platform can be appropriate. The JKS Multi-material Plastic Profile Extrusion Line uses SJ45, SJ50, and SJ65 single screw extruders and can process PP, PE, PVC, PS, PC, and ABS. The Solid Plastic Rod Extrusion Line uses SJ45 and SJ65 for PP, PE, PA, and POM, producing rod diameters from 6 mm to 200 mm. These examples show why the SJ series is described as versatile for thermoplastic processing.

Comparison Table: JKS SJ Single Screw vs. JKS SJSZ Conical Twin Screw

Frequently Asked Questions

What is the difference between a single screw extruder and a conical twin screw extruder?

JKS SJ single screw extruders are designed for thermoplastics such as PVC, PP, PE, Nylon, and ABS. JKS SJSZ conical twin screw extruders are designed for direct extrusion of PVC powder into pipes, sheets, bars, profiles, and similar products.

Can the JKS SJ single screw extruder process PVC?

Yes. The JKS SJ series is listed for PVC, PP, PE, Nylon, and ABS. Depending on the mold and auxiliary equipment, it can produce pipes, rods, films, pellets, coated products, and blow-molded bottles.

Which screw type does JKS use for PVC pipe extrusion lines?

JKS PVC water supply and drainage pipe lines use conical twin screw extruders. The PVC63, PVC250, and PVC630 lines have documented outputs of 270 kg/h, 450 kg/h, and 800 kg/h respectively in JKS product information.

How do I choose between an SJ and SJSZ machine?

Start with your raw material form, finished product geometry, and output target. JKS documents the SJSZ series for direct PVC powder extrusion, while the SJ series covers thermoplastics such as PVC, PP, PE, Nylon, and ABS in general applications. Use the model output tables above as a first filter, then ask the manufacturer to confirm the complete line configuration.

Conclusion

Neither the SJ single screw platform nor the SJSZ conical twin screw platform is universally better. The correct plastic extrusion machine depends on what you feed, what you want to produce, and how much output you need. JKS can build both types, and both use 38CrMoAlA nitrided alloy steel screws and barrels with Q235 carbon steel frames.

For new line projects, bring these three facts to the supplier conversation: raw material type, finished product specification, and required output. With that information, a manufacturer such as JKS Machinery can recommend whether an SJ single screw extruder or an SJSZ conical twin screw extruder is the right core for your production line.

Contact JKS Machinery for a line recommendation or to discuss your raw material and output requirements.
Name: Gordon
Email: gordon@jksjx.com
Tel/WhatsApp: +86 18601577228

Download the JKS Machinery brochure for more project information.