Development Of Apparatus And Protocol For Testing Of Sand At High Temperatures In The Foundry

In order to increase productivity and improve quality, the metal casting industry has realized the need for near-net shape casting. For example, in the automotive industry, power train components are designed for usage in close tolerance. One goal of the foundry engineer is to produce cores and molds of consistent dimensional accuracy, and hence a casting satisfying the tight tolerances of the automotive industry. This objective inevitably will result in improved quality and more efficient production. The developers and users of chemical binders, in hot or cold box cores or on patterns for mold, all have these issues in mind. One of the main aspects when talking about dimensional accuracy is thermal distortion of the molds and cores. To the best of our knowledge currently there is no testing protocol to determine thermal distortion in a controlled fashion at pouring temperatures. Practitioners use data based on tests at room temperature in order to predict mold behavior at high temperatures. An apparatus and a specific methodology to measure thermal distortion have been proposed and developed by the authors, and it is reported in this paper. The proposed apparatus, now in its second generation, is simple to operate and the test specimen is a disc piece, which is already used for transverse strength testing of chemically bonded sands. The proposed protocol allows examination of thermo-mechanical properties of the specific sand-binder combination. Thermal distortion curves obtained for various sand-binder-catalyst combinations, when tested for aluminum castings, are presented. This project was carried out over several semesters, where students in the capstone design project course sequence participated. This is a very good example of collaboration between industry and university, with benefits for both sides. The students were excited about working on a project with great potential for industrial applicability, and industry was more than willing to provide needed materials for the project to become a reality. The results obtained so far are encouraging and it is believed that the proposed methodology can be used for better process control to establish a materials control program and for dimensional control of cores and molds. The designed apparatus is another tool that would aid in identifying correct amounts of binder materials and catalysts, and for predicting the behavior of the core and mold material in thermomechanical application.