Methods to Determine, Influence and Improve the Flowability of Sand Mixtures

Abstract

Due to increasing environmental awareness, more and more foundries started to replace the organic binders with an environment-friendly binder system based on inorganics. However, inorganic binder systems can only replace the conventional organic binders if all requirements, set by the foundry industry are being fulfilled. One of these is the production of high-quality cores, indicative of good compaction, no surface defects, and high surface smoothness. Such types of cores can only be manufactured when the sand mixture shows sufficient flowability. This chapter presents a study on the flowability of various types of sand mixtures all including inorganic binder systems finally to be used for the production of sand cores for the foundry industry. Results have shown that the flowability of sand mixtures can be modified and improved by (1) the addition of small amounts of surface-active agents and/or (2) well-chosen additives characterized by micro-sized spherical particles. The addition of only a few amounts of surface-active agents resulted in a significant improvement of flowability and thus of core quality. Similar results were achieved with the use of small concentrations of spherical micro-sized particles.