Optimierung der Sieblinie durch Konfektionierung

Die gesteigerten Anforderungen an die Gussteile und ein zunehmender Automatisierungsgrad in der Fertigung erfordern neue Methoden, Sande entsprechend einer optimierten Sollkörnung mit geringen Schwankungsbreiten darzustellen. Die geologisch bedingten natürlichen Schwankungen einer Lagerstätte können kompensiert werden, indem der Sand großtechnisch gesiebt und anschließend nach Vorgabe gemischt wird. Graded sands: Improvements in grain-size distribution
The developments in foundry industry cause rising demands on the geometry and surface of castings. Especially a high degree of automation and high production speeds as well as challenging geometries require an optimized and constant quality of the processed materials. The silica sand from Haltern is well known in foundry industry for its excellent properties in grain shape and purity. However, its capability in terms of high specialized applications is still underestimated. Additionally to the standard grain sizes, the products can be filtered by an industrial sieve stack and recombine into an ideal grain- size distribution. In the concrete and construction industry, modulating the packing density is an important instrument to achieve special strength properties. By applying this context to foundry industry, the complex interaction of involved parameters has to be considered. The optimization of one parameter causes a change of several further parameters. For instance, a grain-size distribution to arrange a high packing density results into high bending strengths but exhibits low gas permeability. Thus, the impact of the grain-size distribution on numerous parameters and its dependencies on each other were followed by means of a program for statistical analysis and presented in this work. For a better understanding of the underlying interactions, the amount of used cold-box binder system was varied between 0.5 and 0.9 %. The bending strength, gas permeability, surface roughness, bulk density and flow behavior of the sand were detected as responses. Several resulting correlations are presented here. This dataset and the possibility to recombine graded sieve fractions with high accuracy offer us an instrument to produce improved grading curves unerringly. Rubrik: TECHNIK