This paper aims to design lattice structures for rapid-investment casting (RIC), and the goal of the design methodology is to minimize casting defects that are related to the lattice topology. RIC can take full advantage of the unprecedented design freedom provided by AM. Since design for RIC has multiple objectives, we limit our study to lattice structures that already have good printability, i.e., self-supported and open-celled, and improve their castability. To find the relationship between topological features and casting performance, various lattice topologies underwent mold flow simulation, finite element analysis, casting experiments, and grain structure analysis. From the results, the features established to affect casting performance in descending order of importance are relative strut size, joint number, joint valence, and strut angle distribution. The features deemed to have the most significant effect on tensile and shear mechanical performance are strut angle distribution, joint number, and joint valence. The practical application of these findings is the ability to optimize the lattice topology with the end goal of manufacturing complex lattice structures using RIC. These lattice structures can be used to create lightweight components with optimized functionality for various applications such as aerospace and medical.

With the emergence of new metal AM (additive manufacturing) methods, rapid IC (investment casting), a variation of conventional investment casting has been a popular topic of research in the fields of: aerospace, dentistry and biomedical engineering. RIC (Rapid investment casting) takes advantage of the additive nature of 3D printing for pattern making which allows for more complex castings than traditional investment casting. RIC is a manufacturing process that combines the casting knowledge accumulated over five thousand years with relatively novel AM knowledge. The result is a process that can compete with newer metal AM methods with the added benefits of excellent surface finish, fatigue strength and the ability to create parts from almost any metal or metal alloy. This article will focus on research advancements in investment casting, AM and all the topics that are closely related to optimizing these two processes. Beyond that, aerospace, dentistry and biomedical engineering advancements using investment casting will be reviewed.