Alumina and zircon refractory ceramic molds fabrication by additive methods for metal alloys casting

Traditional processes for the foundry molds fabrication need numerous and rather time consuming steps. These processes are not really adapted to small series or prototypes. The research project exposed in this contribution proposes an alternative method combining the advantages of molding (free formulation of metal alloys, economy on material and on time of machining) with those of the additive processes (short steps between 3D-model and final product, very complex geometries available). For short series the selective laser melting process (SLM) allows the building of molds in a very short time compared to the traditional investment casting method. This technique also permits the unique advantage to control the design of the shell thickness and structure in order to have a better control of the thermal fluxes during metal cooling. This would potentially ensure a better control of the casting defaults. In this presentation, molds built with alumina and zircon as raw materials will be presented. Two metallic alloys have been tested in order to validate alumina and zircon as mold materials; the first, AlCu4MgSi chosen as low melting point alloy reference and the second, stainless steel 316L, as high melting point alloy referenc

Functional refractory molds for metal casting built by additive manufacturing

Additive manufacturing is more and more used in the field of industry. This technique is notably employed in investment casting process in order to build cores and models. Nevertheless investment casting remains not cost effective in case of prototypes and very small series due to the quite large amount time needed to build and dry the molds. Additive manufacturing may also be used to directly shape metal parts but several problems are still linked to this technique as the presence of local defects in parts and the limitation of the number of metal or alloy available for this technique on the market. We propose an intermediate method that permits to build directly molds and cores by additive manufacturing using equipment initially dedicated to build metal parts. This method presents the main advantage to cast with a large variety of metals or alloys using a single ceramic material and only one set of building conditions. The properties of the casted parts are very similar with those produced by investment casting. This technique also permits the unique advantage to control the design of the shell thickness and structure in order to have a better control of the thermal fluxes during metal cooling. This would potentially ensure a better control of some casting defects. The use of alumina processed by selective laser melting (SLM) is shown and its outstanding resistance to temperature differential is demonstrated through casting trials with two diffferent representative alloys. Casting trials in industrial conditions will be illustrated