The occurrence of veining and penetration defects in automotive brake rotor castings is well documented. Casting geometries, pouring temperatures, wall thickness specifications and volume requirements all affect the alternatives available to solve surface defect problems. A new, sand additive product has been found to significantly impact the casting surface finish and defect occurrence rate of a test foundry's products. A case study review highlights the positive and negative aspects of the new product in a high-production environment. Additionally, DOE (design of experiments) sand testing was conducted to determine the expected sand tensile results from varied resin types, resin levels, additive types and additive levels. The case study casting results show that the new additive provides improved casting surface finish and lower penetration defects. Other benefits from the product were cleaning room cost reductions that justified material costs, cleaner running tooling than other sand additive alternatives and extra or additional sand mix volume. The additive was a significantly lower cost alternative than coating cores with refractory coating, for process and capital requirement standpoints.
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