ISSUE 2/2013

/// 03
Prat, J.; Stötzel, R.; Yilmaz, I.
A new sand additive to control veining and eliminate the need for refractory coatings

Sand additives are widely used within the foundry industry to control veining defects on cored surfaces. They are most often used in conjunction with refractory coatings which improve surface finish and control metal penetration, thus requiring two additional products and processes for high quality castings. A new product has been developed that combines the positive effects of additives and coatings into a single material. The new additive is based on low density alumina silicate ceramic (LDASC) with a small addition of fluxing material.  Testing has shown that this material has unique expansion and contraction properties that both eliminate veining and provide a superior casting surface finish. A 5 % addition level is sufficient for most applications. A variety of automotive castings including disc brake rotors, brake calipers, and steering knuckles have been produced with good results without the need for coatings. This paper reviews the development of the new additive and shows the potential benefits in both quality and cost.   




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