Influence of Filter Structure and Casting System on Filtration Efficiency in Aluminum Mold Casting

Ceramic foam filtersFilter haveCasting been usedFiltration efficiency in aluminumAluminum foundries since 1974 to increase the purity of the melt. In practice, the implementation of the foam ceramic filterFilter in the castingCasting system is in most cases a question of space on the pattern plate. It does not follow any defined rules but is at best guided by design recommendations from the filter manufacturers. To increase the filtration efficiencyFiltration efficiency, the filterFilter position in the castingCasting system is examined. For this, 20 and 30 ppi filters were scanned with computer tomography (CT). The data from the CT were then loaded into the simulationSimulation program Flow 3D. With this program, four different filter positions as well as the influence of the filter length and roughness of the filter surface are investigated concerning their filtration effectiveness. The simulationSimulation results are subsequently evaluated with castingCasting trials. For this, four different molds for four different filterFilter positions were created. The same alloy (AlSi7) was used for the trials as for the simulation. To study the behavior of particles during the filtration process, impurities were added to the melt using 3 wt.% Al2O3 - Metal Matrix Composite. After the samples were casted, the filters are cut out and the Al2O3 particles in the filter are counted for each filter position. The comparability of the casting trials and the results of the simulation have been examined.