The Breakdown of large complex cylinder head core is close related to the hot strength-Toughness propertiesof precoated phenolic resin sand during the drawing of patterns. In this paper

more efficient measuring method of evaluating the hot strength-toughness properties was introduced; main factors which influence on the hot strength-toughness properties was studied; some ways improving the hot strength-toughness properties was presented and the good results was obtained in production practice.