PET Flakes & Glass Fiber Twin Screw Pelletizing Line

The SUHUI PET flakes glass fiber twin screw pelletizing line produces high-performance engineering plastic pellets by compounding recycled PET flakes with glass fiber reinforcement (10–40% loading). The resulting composite pellets deliver significantly enhanced tensile strength, flexural modulus, thermal stability, and dimensional rigidity compared to unreinforced recycled PET.

Designed for the demanding requirements of automotive, electronics, and industrial component manufacturing, these glass fiber reinforced PET pellets replace virgin engineering plastics in applications including structural housings, gears, brackets, and load-bearing components. The twin-screw compounding process ensures precise, uniform glass fiber dispersion throughout the PET matrix with minimal fiber breakage and polymer degradation.

By repurposing post-consumer PET bottle flakes as the base matrix material, the SUHUI line supports sustainable, cost-effective production of high-value engineering plastic compounds that would otherwise require virgin PET resin.

Key Features of SUHUI PET Glass Fiber Twin Screw Pelletizing Line

• Co-Rotating Twin-Screw Extruder: High-torque, co-rotating twin screws with corrosion-resistant barrel lining ensure thorough mixing, homogeneous dispersion of glass fibers, and consistent compound quality.
• Wear-Resistant Components: Hardened alloy barrel segments and screw elements withstand the highly abrasive nature of glass fiber processing, extending service life significantly.
• Precise Gravimetric Fiber Dosing: Loss-in-weight gravimetric feeders control glass fiber content with high accuracy (±0.5%), enabling customized mechanical property profiles from 10% to 40% fiber loading.
• High-Temperature Processing Capability: Barrel heating zones reach up to 300°C to fully melt PET without degrading glass fiber sizing or polymer chains during compounding.
• Vacuum Degassing System: Integrated vacuum vent removes residual moisture, volatiles, and entrapped air from the melt, producing defect-free, void-free pellets.
• Strand Pelletizing Unit: Extruded strands are water-cooled and cut into uniform 2–5 mm pellets with low dust generation and consistent geometry.
• PLC Automated Control: Touchscreen control system adjusts barrel temperature profiles, screw speed, and gravimetric feeding ratios in real time for consistent output quality.
• Energy Recovery System: Heat exchangers and insulated barrel sections reduce thermal energy loss and lower power consumption by 15–20% compared to uninsulated designs.

PET Glass Fiber Compounding Process Workflow

1. PET Flake Pre-Drying: Recycled PET flakes are dried in a dehumidifying dryer to reduce moisture content below 0.02%, preventing hydrolytic degradation of polymer chains during high-temperature extrusion.
2. Glass Fiber Preparation: Pre-cut glass fiber rovings or chopped strands are stored in a humidity-controlled silo and fed via a dedicated gravimetric side feeder, maintaining precise moisture content to protect fiber sizing.
3. Gravimetric Feeding: Dried PET flakes and glass fibers are simultaneously and independently fed into the twin-screw extruder via separate gravimetric loss-in-weight feeders, maintaining the target fiber loading ratio.
4. Melting & Compounding: The co-rotating twin screws melt the PET flakes and progressively incorporate glass fibers into the polymer matrix through controlled kneading and distributive mixing elements.
5. Vacuum Degassing: A mid-barrel vacuum vent removes residual moisture, acetaldehyde, and other volatiles from the melt to produce void-free, high-clarity compound pellets.
6. Die Head Extrusion: The fully compounded PET/glass fiber melt is forced through a multi-hole strand die, producing multiple continuous strands of uniform cross-section.
7. Strand Cooling: Extruded strands pass through a water cooling bath to solidify and reduce strand temperature before cutting.
8. Pelletizing: Cooled strands are fed into a strand pelletizer that cuts them into uniform 2–5 mm cylindrical pellets with consistent length and low fines generation.
9. Screening & Quality Control: Pellets pass through a vibratory sieve to remove undersized fines and oversized pieces. Samples are tested for fiber content, IV value, and mechanical properties.
10. Packaging: Finished glass fiber reinforced PET pellets are conveyed to storage silos or automatically weighed and bagged for shipment to automotive, electronics, or industrial customers.

Frequently Asked Questions

What is the glass fiber loading range for this pelletizing line?

The SUHUI PET flakes glass fiber twin screw pelletizing line supports glass fiber loadings from 10% to 40% by weight, controlled with ±0.5% accuracy using loss-in-weight gravimetric feeders. The target fiber content can be adjusted in real time via the PLC control system to meet specific mechanical property requirements for different end applications.

Why must PET flakes be pre-dried before compounding?

PET is highly hygroscopic and will undergo hydrolytic degradation at processing temperatures if moisture content exceeds 0.02%. Pre-drying in a dehumidifying dryer reduces moisture to below this threshold, preventing chain scission, IV value loss, and surface defects in the final glass fiber reinforced pellets.

What are the typical applications for glass fiber reinforced recycled PET pellets?

Glass fiber reinforced recycled PET pellets produced by this line are used in automotive structural components including housings, brackets, and load-bearing parts; electronics enclosures and connectors; and industrial components requiring high stiffness, dimensional stability, and thermal resistance. They serve as a cost-effective, sustainable replacement for virgin engineering plastics.

How does the twin-screw design minimize glass fiber breakage?

The co-rotating twin-screw extruder uses controlled kneading and distributive mixing elements that progressively incorporate glass fibers into the polymer matrix without excessive mechanical shear. Screw geometry and processing parameters are optimized to balance thorough fiber dispersion with minimal fiber length reduction, preserving the reinforcement efficiency of the glass fibers in the final compound.

What pellet size does the line produce?

The strand pelletizing unit produces uniform 2–5 mm cylindrical pellets with consistent length and low fines generation. Pellets pass through a vibratory screening stage to remove undersized fines and oversized pieces before packaging, ensuring consistent pellet geometry for downstream injection molding and extrusion processes.

Can the line process different fiber types beyond standard glass fiber?

The line is primarily configured for glass fiber reinforcement of PET. With appropriate screw configuration adjustments and wear-resistant component upgrades, it can also process carbon fiber or mineral filler compounds. SUHUI engineers assess feedstock compatibility and recommend the appropriate configuration based on fiber type, loading percentage, and target compound properties.