3D Printed Smart Mold for Sand Casting: Monitoring Pre-Pour Binder Curing

The benefits of additive manufacturing for fabricating complex sacrificial sand molds for geometrically-complex metal castings is revolutionizing the foundry industry driven by a digital manufacturing paradigm. The design freedom of 3D printing allows for new mold designs

• not possible with traditional approaches - such as helical sprues, varying wall thickness to tailor the thermal history, and spatially-varying lattice castings. However, research on the curing time of printed molds, including the aging of printed molds, requires more exploration. This study describes the experimental evaluation of 3D printed specimens in which embedded environmental sensors were fully encapsulated into sand blocks during an interruption of the binder jetting process. Subsequently, over a 28 day duration, humidity, volatile organic compound generation, temperature and barometric pressure were captured for three environmental treatments. Mechanical testing of standard test specimens subjected to the same conditions was conducted. The sand structures held in high (uncontrolled) humidity and at reduced temperature were statistically significantly weaker than a third treatment based on the hypothesis that high humidity and/or low temperatures impede curing. The use of embedded sensors could provide guidelines for mold and core storage conditions as well as in high-value production to inform the minimum (for full curing) and maximum duration (mold expiration) after printing to identify the optimal time to pour metal during the life of a printed sand mold.