Serial Production of Cellular Structures – No Additives Allowed!

Abstract

As reported before, the Lightweight design department of the Fraunhofer Institute IWU is collaborating with several foundries in manifold projects. The objectives show a large variety starting with energy management activities and leading to product and technology development. Especially in high pressure die casting, most of the products are material minimized till the edge of the castability. The wall thickness is decreased to their very limits, holes are integrated for lightweight reasons and structures modified by topology optimization pushing this traditional industrial sector to the newest state of technology.Many attempts have been published trying to combine that high level serial production technology with the cellular structures for lightweight reasons on the one hand and for material efficiency on the other. Anyway, till now none of them is dealing with real serial die casting parts. The geometry of the parts needs to be adapted to the requirements of the pore generation procedure. As these approaches are rather complex, in some cases the invested energy, time and additives consume the savings reached by the pore integration.The intention of the project is based upon the omnipresent resource efficiency. By intensive technological investigation of the state of the art and several practical test runs, almost all published strategies of pore generation in high pressure die casting have been analyzed. The industrial partner of the project rejected all of the current approaches as irrelevant for serial application forcing us to create new ideas. Differing from common metal foam structures the objected material savings are around 20-25%. By changing the die-casting-machine setup and several parameters the first parts in original geometry have been realized reaching the target of material reduction. Mostly homogenous pores have been integrated in common serial parts containing a wall thickness of below 3mm while the outer shell is still completely closed and no visual differences compared to the conventionally produced parts occur.