Finite Element Analysis of Multi-Material Die-Cast Tooling by Additive Manufacturing

Abstract

The predominant challenge encountered in the high-pressure die casting of aluminum is the deterioration of casting dies because of thermal fatigue or heat checking. This issue largely stems from the inadequate thermal conductivity of the materials used for the dies. In this thesis, the focus is on evaluating the thermal and mechanical behavior of multi-material dies manufactured through additive manufacturing. These suggested dies are made of traditional die material and feature a shell with TPMS core, into which a material with superior thermal conductivity is infused. The investigation is conducted through computational finite element analysis (FEA) to assess the performance by comparing temperature and stress distributions withing test specimens. The material properties of the hybrid material, which includes a TPMS made of tool steel infused with a high thermal conductivity material, were determined through the process of homogenization. Rule of mixture as well as evaluation by computational calculations were applied to derive the relationship between infill volume fraction and material properties of hybrid structure. Experimental thermal results of the hybrid specimen were compared with the computational results with using material properties derived by homogenization. Upon observing similarities in the results derived by both the approaches, homogenization results were validated. Two case studies are discussed in this work to computationally derive the effectiveness of multi-material tooling. The geometries used in both the case studies present similarities to geometries used in actual die casting experiments and/or productions. In both cases, geometries were given boundary conditions observed in actual die-casting testing and manufacturing. Notable decreases in both the peak temperature and the temperature gradients within the die body were observed, correlating directly to the volume fraction of the infill material. Furthermore, a significant reduction in cyclic principal stresses was noted in the hybrid tooling configurations, indicating enhanced resistance to thermal cracking.