Integral foam molding

Integral foam molding (IFM) is an economical way to produce castings with integrated cellular structure, i.e. a solid skin and a foamed core. IFM is known for polymers since more than four decades and well established there in industrial production. Polymer integral foam parts are accepted as a material system with own properties which simplifies designs, reduces production costs and weight, and increases stiffness and overall strength. On the other hand, integral foam molding for metals is a new field of research. The development of metal based integral foam molding processes at WTM moves along analogous paths as that of polymers by transferring and adapting successful molding technologies for polymer integral foam to metals. Two molding techniques for metal integral foam are presented, a low and a high pressure process. During the low pressure integral foam molding process, the molten metal charged with blowing agent is injected into a permanent steel mold without completely filling it. In this case, the mold gets eventually filled by foam expansion. The strategy of the high pressure integral foam molding process HP-IFM is to initiate foaming by expansion of the mold cavity after it is completely filled with the mixture of the metal melt and the blowing agent.