Design of rapid investment casting

Rapid investment casting (RIC) is a production process of indirect additive manufacturing (I-am) metal parts formed by the combination of 3D printing (3DP) and investment casting. It refers to using the 3D printed model as the wax mold of investment casting, and then coating ceramic materials on the surface of the model, After wax removal and sintering, the ceramic shell is obtained, and then pouring is carried out to obtain a manufacturing process of metal parts. 3D printing can directly print complex wax mold, so that the geometric shape, internal structure and fineness of wax mold are not limited by the traditional wax mold pressing mold, which greatly expands the degree of freedom of investment casting parts.

Although the application of direct additive manufacturing (d-am) metal parts in aerospace, medical and other fields has made rapid development in recent years, it still has some disadvantages, such as high cost, limited materials, low precision, difficult removal of residual powder and support, etc. at present, it is difficult to become a conventional production process in the general industrial field. Compared with d-am, rapid investment casting has the advantages of mature process, low cost and large-size parts. It has great application prospects in aerospace and general industrial manufacturing.

Like direct additive manufacturing, rapid investment casting can fully reflect its advantages only in manufacturing parts with complex topology, while for conventional geometric parts, traditional manufacturing process is more suitable. The conventional geometric structure is restricted by the traditional manufacturing process, so that its mechanical properties can not be optimized. On the one hand, the development of rapid investment casting makes it possible to manufacture complex topology; On the other hand, only good topology design can give full play to the application advantages of rapid investment casting.

The idea of topology design is to remove the internal redundant materials that do not bear stress or affect performance, so as to obtain better comprehensive mechanical properties. It includes topology optimization design based on optimization algorithm and direct topology design of internal lattice structure. This paper is called lattice topology design.

Topology optimization design refers to the redesign, analysis and evaluation of the optimization model based on the topology optimization results. Lattice topology design refers to the lattice filling of the non key load-bearing parts of traditional solid block parts to make the parts lighter or obtain better thermodynamic and vibrational properties. Topology optimization design and lattice topology design are collectively called topology design in this paper. In a broad sense, it is an integrated process of CAD / CAE / CAM.

The current problem is that the CAD / CAE / CAM integrated software for AM and topology design has not appeared, which is the key obstacle to the further popularization and application of am. It is aimed at the topology design and analysis of I-am process of rapid investment casting, including topology modeling (CAD), structural analysis (CAE) and casting process analysis (CACE). It is expected to explore an integrated CAD / CAE / CACE method for ric parts.