EPS Pre-Foaming Machine

Overview

The pre-foaming machine is the starting point of every EPS production line. It heats raw polystyrene beads with steam, causing the dissolved pentane gas to expand each bead into a lightweight foam cell. The result is pre-expanded EPS beads at a controlled target density, ready for curing and subsequent molding.

Eprotech manufactures both continuous and batch (discontinuous) pre-expanders to suit different production scales and process requirements.

Continuous vs. Batch

Continuous pre-expanders feed raw material in a steady stream and produce expanded beads without interruption. They are suited to high-volume operations where consistent output is the priority. Capacities range from several hundred to 4,000 kg/hr depending on model and target density.

Batch pre-expanders process a measured charge of raw material per cycle. They offer more precise control over individual batches and are well suited to operations that produce multiple densities or that need flexibility in production scheduling. Chamber volumes range from 0.15 to 5.5 m³.

Density Control

Target density is controlled by regulating steam pressure (typically 0.3 to 0.6 bar), exposure time, and material feed rate. The PLC system manages these parameters automatically, maintaining output within the target range of 10 to 40 kg/m³.

For tighter density tolerance, the pre-foaming machine can be paired with Eprotech’s automatic density controller, which samples output each cycle and adjusts parameters in real time.

Integration

Pre-foaming machines connect to the rest of the bead expansion line via automated bead transfer systems, then to curing silos for the stabilization period before molding.