Herstellung mikrostrukturierter Oberflächen im Feingießverfahren

摘要

This paper examines the achievable molding accuracies of micro-structured surfaces by use of the investment casting process and identifies the significant influence variables on the casting result. Using the demonstrator part "air restrictors with an inner shark skin surface" it was also tested if the process can be transferred to a real casting process. For the examinations structured surfaces of varying size and geometry were chosen (trapezoidal, triangular and riblet-structures with heights from 90 µm to 5 µm). The process steps of fabricating the wax pattern, the mold and the cast part were characterized. On the wax pattern all structures could be reproduced without loss in the molding accuracy by adjusting of the process parameters. Similarly, all structures have been reproducibly transferred into the mold consisting of investment powder. From sizes below 15µm, however, a superposition of the structure geometry by the surface roughness of the mold was visible. Unlike in the mold, structures under 15 µm were not well reproduced in the casting. The reason for this was the poor wetting behavior of the melt on the mold surface.