Bentonite Modification to Meet Today's Molding Requirements

摘要

High casting quality demand, larger parts, thinner parts, more cores and higher productivity have made greensand casting process complex and increased greensand requirements. To meet today's requirements 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 so there is not one excellent bentonite for all foundries. Bentonite, possible modification and additives must be customized. Bentonite is a very complex mineral and the relationship between compositions and binding properties is not always a scientific explanation. At the end of a day suppliers and foundries are interested in molding properties. Bentonites are as different as foundry requirements and by blending bentonite often a good composition can be created. Often blending bentonites is not economic for logistical reasons and bentonites can be modified to achieve better foundry performance. The modification can be completed during bentonite processing or/and by blending / addition of other products. We diversify between blending in additives and bentonite modification, what means there is an impact on the bentonite structure. Modified bentonite can provide improved dispersability, flowability, higher green- and hot strength, less requirement of coal addition and lower bentonite consumption. These effects contribute to sustainable production in terms of casting quality, low consumption and less impact on environment.