EPS Batch Pre-expander Machine — Precise Density Control for EPS Production
Watch the pre-expander running in fully automatic mode below.
The YouXin EPS Batch Pre-expander Machine produces expandable polystyrene beads at the exact density you need, with a tolerance of ±1.5%. It is the essential first step in any EPS manufacturing line — transforming raw EPS resin into lightweight expanded beads ready for aging, molding, and final shaping.
How the EPS Pre-expander Works
During pre-expansion, EPS resin is fed into a stainless steel expansion chamber equipped with an agitator and controlled steam supply. The beads expand as steam heats them, increasing in diameter while density decreases. After exiting the chamber, expanded beads pass through a fluid bed dryer to remove moisture, then flow into aging silos for stabilization.
Machine Specifications
| Model | Chamber Diameter | Chamber Height | Density Tolerance | Output (@15 kg/m³) |
|---|---|---|---|---|
| SPJY-1600G | 1600 mm | 2500 mm | ±1.5% | 1600–1800 kg/h |
| SPJY-2000G | 2000 mm | 2000 mm | ±1.5% | 2000–2200 kg/h |
Key Features
- CE certified with multiple safety features
- PID system ensures precise density control
- Mettler Toledo weighing sensor for weight accuracy
- Japanese Yoshitake pressure reduction valve for steam control
- Dual vibration level sensors for material detection
- Waste heat collection and reuse system for energy savings
- Frequency-controlled agitator speed during expansion
- Fluid bed dryer with built-in heater to shorten aging time
- Optional second expansion unit for ultra-low density beads
- Optional automatic density weighing and printer system
- Compatible with YouXin Automatic Silo System for full automation
Expansion Chamber & Agitator
The chamber is constructed from SUS 304 stainless steel — cylindrical inside with a square outer shell and insulation layer. The agitator is also SUS 304 stainless steel, with speed adjustable by frequency converter during different steaming stages. A side-mounted discharge door enables fast emptying between cycles.
Screw Loading System
A screw loading machine with a 1.5 m³ tank (approx. 1200 kg EPS beads) feeds resin into the dosing unit, which then fills the expansion chamber by gravity.
Fluid Bed Dryer
Equipped with a waste steam collection cover and SUS 304 stainless steel floor. An integrated steam-air heat exchanger prevents thermal shock to the beads. At the discharge end, a rotary system routes expanded beads to designated silos.
Control Panel & Density Weighing
The main cabinet features a security lock, Delta or Siemens touch screen and PLC. All parameters and recipes can be added, revised, and saved. After each cycle, the density weighing system extracts a fixed volume from the dryer and weighs it — density data can be saved in the PLC or printed.
Major Components
- Touch Screen & PLC: Siemens (Germany)
- Temperature & Pressure Sensors: Siemens (Germany)
- Electronics: Schneider (France)
- Agitator Motor: SEW (Germany)
- Butterfly Valve: Flowx (Italy)
- Weight Sensor: Mettler Toledo (Switzerland)
- Pressure Reduction Valve: Yoshitake (Japan)
- Pneumatic Parts: SMC (Japan)
- Photo Sensor: Autonics (Korea)
Where this machine is used
Every EPS plant is a chain: bead preparation in front, moulding in the middle, cutting and packing behind. These are the three application areas where this model is most often specified.
| Application | What it produces | Read more |
|---|---|---|
| Packaging shapes and trays | Bead density set before moulding decides cushioning performance | EPS packaging |
| Insulated cold chain packaging | Density decides thermal conductivity – the root of hold time | EPS for insulated cold chain packaging |
| Passive house envelopes | Density held to a tight band across 200-300 mm board | EPS for passive house |
| Insulation board | Stable density in, stable lambda out | EPS insulation |
Tell us the product, the density and the output you need, and we will size the machine and the rest of the line around it. Send us your specification.