The YouXin EPS Batch Pre-expander produces expandable polystyrene beads of the desired density with a tolerance of ±1.5%. During pre-expansion, EPS resin is fed into a steam-controlled expansion chamber equipped with an adjustable agitator; the bead diameter increases while density decreases. Expanded beads then pass through a fluid bed dryer to remove moisture before entering the aging silos.
The expansion chamber and agitator are made of SUS 304 stainless steel with an insulation layer. A PID system and a Japanese pressure reduction valve ensure accurate steam control, while a Mettler Toledo weighing sensor with automatic density weighing and printing guarantees stable, verifiable output. A second expansion unit is available for lower densities, and the machine can be combined with the YouXin automatic silo system for fully automated plants.