Additive Freeform Casting (AFFC): A new approach of manufacturing combining additive manufacturing and casting

Anisotropy, slow building rates and restrictions in the size of parts are major disadvantages in additive manufacturing. Using bulk material in a casting process can avoid these disadvantages and provide fast cycle times. Therefore, this paper offers a beneficial combination of both methods. The paper presents a new approach of manufacturing polymer parts combining additive manufacturing and casting. The method uses additive manufacturing to build thin shell structures as a complex mould. These structures are filled with a low-viscous two-component thermoset. The filling material cures inside the mould. This results in a compound structure of mould and casting material. In order to proof the concept, appropriate fast curing casting materials were chosen. Various mould geometries were designed and produced by fused filament fabrication. The leak tightness of the mould material was characterised depending on viscosity and surface tension of the casting thermoset. The combined process was implemented in a first test rig consisting of a filament extrusion head and a two-component dispensing unit. Therefor the dispensing unit was developed and integrated into a 3D printer.