Sand Mold Design for High-Phosphorus Cast Iron Brake Shoe Casting

The production of DR2 brake shoe (UIC 542 Brake Block II) was implemented using a high-phosphorus cast iron of P30 grade together with horizontal casting mold design. The location and size of sand mold gate, sprue and riser were developed to increase railway brake shoe quality. The casting defects and quality of railway brake shoes were also evaluated. The results show that the casting modulus of the shape of brake shoe is about 12.64 whereas a high shrinkage porosity is formed. Low liquid and solidification shrinkages occur when using a low pouring temperature of 1180 degrees C. Pouring the molten metal at the lower 1150 degrees C temperature might risk precipitation and separation of graphite to the surface from the casting metal matrix. The improved mold design can reduce the porosity defects in brake shoe. An economical design with low riser modulus or feeding modulus can help the molten metal feed in casting, but it was effective only at the beginning stage of solidification. The horizontal mold with side parting line tapered sprue and two-sided tapered riser with 6 mm gate thickness shows less shrinkage porosity without cavity formation than the other horizontal mold conditions. This design can be implemented to cast railway brake shoes based on 7% allowed porosity. In fact, the production advantage of the horizontal mold with improved design is that the side riser is easy to knock off and it is better in regard to time and cost saving for riser removal and finishing than the vertical mold with top riser.