ISSUE 2/2014

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Snelling, D. A.; Kay, R.; Druschitz, A.; Williams, C. B. Mitigating gas defects in castings produced from 3D printed molds

3D printing of sand molds for metal casting using proprietary sand/polymer and binder solutions can produce complex mold geometries that are not possible to produce by customary molding processes. However, the required large percentage of binder (>8 % as molded and >3 % after “drying and curing”) generates much more gas during casting compared to traditional no-bake molding (<1.5 % binder). The increased gas generation during the casting process leads to challenges in creating a defect free casting. In an effort to mitigate issues due to significant gas generation during casting, the authors explored the effects of curing time and temperature on the residual binder content before casting. Specifically, the authors compared the binder burnout characteristics and the tensile strength of sand created by 3D printing and conventional no-bake molding and developed a mold curing cycle for 3D printed molds.

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