Speakers: C. Grefhorst, S. Böhnke (S&B Germany), N. Richardson (S&B UK), V. LaFay (S&B USA). Company Name: S&B Industrial Minerals.

High demand for casting quality, larger, thinner parts, more cores and higher productivity have increased the complexity of the greensand casting process and performance requirements. To comply with this high demand, bentonite must be fast in preparation (muller / mixer), durable (low consumption), apply high green- and hot strength (no broken molds), and good mold break down (shake out) after casting. Each foundry installation and process is different; one bentonite cannot offer the solution for all! Bentonite and modification with additives must be individually customized.
Bentonite is a very complex mineral and the relationship between composition and binding properties is not always scientifically explainable. Suppliers and foundries alike are interested in molding sand properties and performance, however, bentonites are as different as foundry requirements and by blending bentonite, often good composition and synergies can be created. For economic reasons and geographical location, blending bentonites with different properties is not always possible and modification can be considered to improve foundry performance. Modification can be achieved during processing or by blending with additions of other products. There is a clear distinction between the blending of additives and bentonite modification, as bentonite modification means there is an impact on the bentonite structure.
Modified bentonite can provide improved dispersion characteristics, and flowability with higher green- and hot strength. The requirement for the use of organic additives (coal) is reduced with the optimization of bentonite consumption possible. These effects contribute to sustainable production with improved casting quality and low raw material usage with less environmental impact.

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