Economies of Complexity of 3D Printed Sand Molds for Casting

Martof, Ashley
Gullapalli, Ram
Kelly, Jon
Rea, Allison
Lamoncha, Brandon
Walker, Jason M.
Conner, Brett
MacDonald, Eric
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University of Texas at Austin

Additive Manufacturing (more commonly referred to as 3D printing) is resulting in a metamorphosis of the sand casting industry as 3D printed sand molds enable castings of unmatched geometric complexity. The manifold benefits of these molds include: (1) the integration of structural elements such as periodic lattices in order to optimize weight versus strength; (2) the structural inclusion of unique features such as embossed part numbers and/or other details of the production history; and (3) complex geometries that generate new casting applications not possible previously. Additive Manufacturing is often described as providing “complexity for free”, which may not be entirely precise but generally holds true and the identification of castings that are sufficiently complex to benefit from 3D printing is generally left to the intuition of the designer or foundry. New software tools are necessary for foundries to discover opportunities in which the additional costs of 3D printing are compensated by the benefits of increased structural complexity. This paper describes a complexity evaluation tool that scores CAD models to determine the most economical casting approach based on slicing and 2D geometry evaluation. The three potential outcomes include (1) traditional sand casting, (2) AM­-enabled sand casting and (3) a hybrid of the two with 3D printed cores in traditional casting flasks. Several case studies are described and evaluated.