Introduction: DIY particle foaming

Particle foaming of EPS (expanded polystyrene) is a widely used process in the industry and is used to manufacture lightweight and robust products such as packaging, insulation and other applications.
In the introduction to particle foaming in the pressure cooker, we first illustrated the production of molded parts and the industrial process using EPS as an example:
In preparation, the EPS granulate enriched with a blowing agent is heated at over 90 degrees Celsius, causing the beads to expand by 30-50%. After drying, it is fed into the various molds via a hose system and directed into the closed molds via small filling injectors.
The molding process begins with the polystyrene granules being filled into a mold that is a negative of the desired shape of the end product. Steam is then injected into the mold through small openings, causing the beads to foam up and bond together to form a closed-cell structure. Once the steam supply has been stopped, the material can cool and harden.
Particle foaming in a pressure cooker is a good option for initial trials with custom molds. Prototypes can be foamed in molds made of plywood, aluminum mesh or PUR plastic sheets in the pressure cooker.
It is important to take the set parameters into account and adjust them carefully. In addition to the choice of material for the molded part and the tool, the pressure, temperature, duration, wall thickness and properties of the particles are crucial for reproducibility in your own studio.
An oversized pressure cooker was purchased especially for the project, which also creates a pressure of 4 bar – in the hope of being able to foam EPP in this way.