Introduction

When producing plastic sheets, the type of screw extruder you choose affects everything—melting quality, sheet stability, mixing performance, and the final product appearance. Many manufacturers want to know whether a single screw extruder or a twin screw extruder is better for their production line. This guide explains the differences in simple, practical terms so you can choose the right machine for your factory. WYLONG offers both single-screw and twin-screw extrusion lines for PP, PS, PE, PET, PLA, and BIO materials. Understanding the differences helps you match the right machine to your product needs.

What’s a Screw Extruder?

A screw extruder is a machine used to melt, mix, and push plastic materials forward through a mold (die) to form sheets. Inside the barrel, the plastic extruder screw rotates to move raw materials, melt them evenly, and shape them into high-quality plastic sheets. For sheet production, the extruder directly affects transparency, strength, thickness accuracy, and stability.

Overview of Single-Screw Extruders

A single-screw extruder has one screw inside the barrel. It melts and pushes material forward with simple and stable operation. This type of extruder is widely used for PP, PS, and PE sheet production because it works well with clean, uniform materials.

Benefits:

Lower investment cost

Easy operation and maintenance

Good output for simple formulas

Energy-saving

Limitations:

Weaker mixing power

Not ideal for recycled flakes or high-additive materials

Limited control when materials are complicated

WYLONG’s ZHP Single Layer Sheet Plastic Extruder Line and ZHPD ABA Double-Layer Line both use single-screw designs, offering reliable output for standard sheet production.

Overview of Twin-Screw Extruders

A twin screw extruder has two screws working together. They can be co-rotating or counter-rotating. Twin screws give better mixing, better venting, and more stable melting. This makes them ideal for PET, PLA, and BIO materials or any formula that requires strong dispersion.

Benefits:

Strong mixing and blending

Handles recycled materials and additives

Better temperature control

Excellent venting and devolatilization

More uniform melt quality

Limitations:

Higher purchase cost

More complex structure

Higher maintenance requirements

WYLONG’s ZHPET Parallel Twin Screw PET Extruder Line is designed for PET/PLA/BIO sheet production where mixing and venting are very important.

Comparison Between Single-Screw vs Twin-Screw Extruders

Feeding & Material Handling

Single-screw extruders perform best with clean pellets. Twin-screw extruders can handle powders, flakes, recycled materials, and high-filler formulas because the two screws grab and move material more efficiently.

Melting Efficiency

Single screws offer stable melting for simple materials. Twin screws melt more quickly and more evenly, especially when the raw material is difficult to process or heat-sensitive.

Mixing & Dispersion Capability

Mixing is one of the biggest differences. Twin-screw extruders mix materials extremely well, which helps when adding color, fillers, or BIO materials. Single screws have limited mixing power.

Output Stability & Pressure Build-Up

Single screws build strong pressure, making them ideal for shaping stable PP/PS/PE sheets. Twin screws offer smooth output flow, which helps reduce sheet defects when working with recycled PET or PLA.

Material Homogeneity

Twin screws create a more uniform melt. This leads to better transparency, fewer black dots, and smoother sheet surfaces.

Venting & Devolatilization

Twin-screw machines have clear advantages in venting. They remove moisture and gases from PET/PLA, which prevents bubbles and improves sheet clarity. Single screws have weaker venting performance.

Energy Consumption

Single-screw extruders use less energy because of their simple structure. Twin screws consume more energy but are more efficient when processing complex materials.

Maintenance & Operating Complexity

Single-screw machines are easier for new factories. Twin screws require more technical knowledge and careful maintenance because of the modular screw design.

Flexibility in Material Formulation

Twin screws offer much more flexibility. You can add fillers, additives, color, recycled flakes, or BIO materials. Single screws perform best with pure pellets and simple formulas.

Best Materials for Each Extruder

Single Screw: PP, PE, PS, HIPS – simple, clean materials

Twin Screw: PET, PLA, PBAT, BIO materials, recycled materials, and high-additive formulas

Which Extruder Works Best for Sheet Production?

Choose Single-Screw If:

You make PP, PS, or PE sheets

Your formula is simple

You want lower investment cost

You prefer easy operation and low maintenance

Choose Twin-Screw If:

You produce PET or PLA sheet

You use recycled flakes

You require strong mixing and venting

You need stable melt quality and high transparency

Conclusion

Single-screw and twin-screw extruders each have their strengths. Single screws offer simplicity, lower cost, and great output for standard sheet products. Twin screws offer powerful mixing, excellent venting, and better control for PET, PLA, BIO materials, or recycled formulas.

WYLONG provides both options, from single-layer sheet extruder lines to parallel twin-screw PET extruders, ensuring that each customer gets the right machine for their production needs. With over 20 years of experience, patented technology, and stable sheet extrusion solutions, WYLONG can help you build a high-quality and efficient sheet production line that matches your material, budget, and long-term plans.