Runner Systems Containing Ceramic Foam Filters Quantified by “Area Normalized” Bifilm Index Map

Abstract

In the runner system design for aluminum gravity castings, ceramic foam filters were used for reducing the velocity of liquid metal to avoid “bifilm” defects resulting from a high gating velocity (over its critical gating velocity). In this study, three types of runner systems incorporating ceramic foam filters were designed. To observe the flow phenomena in these systems, a water analogy experiment in a transparent plastic mold was utilized. To understand the effect of the filters used in these systems, aluminum sand casting experiments were conducted. The defect contents inside the casting samples in the outlet area of filters were measured by remelt Reduced Pressure Test (remelt RPT) and followed by measuring their bulk densities. A new “bifilm” index map, which uses the index values normalized by the metal area without porosity, was proposed. Finally, an optimized runner system with filter was suggested.