This study clarifies that high porosity aluminum foam can be produced by combining investment casting and centrifugal casting, using CaCO₃ powder as a foaming agent. The conditions of centrifugal casting for producing high porosity foamed aluminum alloys were investigated through experiments. A master model was obtained by using a stereolithography 3D printer to produce a castable resin, and then a plaster mold was produced using the master model. ADC12 aluminum alloy was melted in an electric furnace at 600℃, and 3 mass% CaCO₃ powder (particle size : under 125 μm) preheated to 600℃ was added to the melt. Centrifugal casting was performed by pouring melt into a plaster mold preheated to 600℃ and rotating the mold at 1100 rpm. The obtained precursor was cut into the specimens of φ15 × 10 mm³ in size, which were then heated in an electric furnace at 800℃ for 8 min to perform foaming tests. A maximum porosity of 51% could be obtained by using a combination of investment casting and centrifugal casting. The specimen cut from near the pouring basin foamed strongly when centrifugal force was not applied. The specimen cut from the position furthest from the pouring basin foamed strongly when centrifugal force was applied at 1100 rpm for 30 s. This is considered to be due to the sedimentation of CaCO₃, whose density is higher than that of the melt, by the centrifugal force. These results suggest that in order to obtain a precursor with uniformly dispersed foaming agent particles by centrifugal casting, CaCO₃ powder with a wide diameter distribution should be used, and sedimentation speed should be varied between the particles.

  The furan no-bake process is widely used because of its applicability to a variety of casting materials. In recent years, it has been applied to additive manufacturing systems.

  The furan AM process has advantages in the production of complex or long thin cores.

  Those cores deformed more due to their own weight than in the conventional furan no-bake process. The objective of this study is to determine the deflection characteristics of the mold at room temperature under the application of equally distributed loads. The transverse strength and deflection of molds were measured under various stress conditions, curing time, and humidity conditions. The deflection of molds increases as stress increases or curing time decreases. On the other hand, there is no correlation between transverse strength and deflection. It is suggested that the progressive curing leads to an increase in the degree of polymerization, increase in resin viscosity, and increase in deformation resistance. The deflection characteristics of the mold at ambient temperature are similar to the creep behavior of chemically cross-linked polymers, and it is influenced by the viscoelastic properties of furan resins. Under high humidity, extremely large deflections of molds are observed, which is due to the softening of the furan resin as it absorbs moisture.