Bridging additive manufacturing and sand casting: Utilizing foundry sand

Although additive manufacturing technology is available for the direct fabrication of metal parts, the process is still in a juvenile state compared to older metal fabrication methods such as sand casting. Therefore, limited standards are available stipulating the use of additively-manufactured parts in critical service conditions such as extreme environments or safety components. However, since sand casting is suited for multiple units of parts, the time and resources needed to produce a single part through sand casting is not ideal for a competitive market. Although additive manufacturing or 3D printing has been combined with metal casting in the past through rapid casting to fabricate sand molds directly, the sand used is stipulated by the 3D printer. The use of specialized sand may result in changes to infrastructure and large amounts of additional sand required to be stored on location. The main question we sought to answer was if traditional foundry sand or non-standard sand could be used within a 3D printing system? We report herein that the although the increase in surface roughness may be tolerable, the use of foundry sand within a 3D printer produces molds with less than optimal results, mainly due to the absence of compaction. Binder bleeding via the liquid binder jetting process also contributes to a loss in dimensional quality.