Steel Hollow Sphere Structures for Energy Efficient Foaming Tools

The foaming of polystyrene (PS) and polypropylene (PP) particle foam parts is a highly energy consuming process. State of the art is foaming the pre-expanded PP or PE particles in foaming tools made of aluminum by saturated steam. While the foaming temperature of PP is about 150 °C the tool and the foamed part have to be cooled down to approx. 65 °C to remove the foam part from the tool in each manufacturing cycle. Because of the heat capacity of the foaming tool, the energy loss is about 90 % of the total used energy amount. So reduction of energy consumption during the foaming process has a high economic and ecological importance. Figure 1 shows a typical tool for particle foam parts.