先进材料疑固实验室 Sand Casting Laboratory of Advanced Materials Solidification Requirements for sand molds: Refractoriness:the ability to withstand high temperatures. (sufficient for high melting point metals such as steel) o Cohesiveness:the ability to retain a given shape when packed into a mold Permeability:the ability to permit gas to escape through the walls Collapsibility:the ability to permit the metal to shrink after it solidifies,and be broken to remove casting 上海充通大￥ SHANGHAI JIAO TONG UNIVERSITY
Requirements for sand molds: • Refractoriness: the ability to withstand high temperatures. (sufficient for high melting point metals such as steel) • Cohesiveness: the ability to retain a given shape when packed into a mold • Permeability: the ability to permit gas to escape through the walls • Collapsibility: the ability to permit the metal to shrink after it solidifies, and be broken to remove casting Sand Casting
先进材料疑固实验室 Sand Casting Laboratory of Advanced Materials Solidification Where does the refractoriness come from? From the nature of sand:High melting point. ory of vanced Materals S 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY
Where does the refractoriness come from? From the nature of sand: High melting point. Sand Casting
先进材料疑固实验室 Sand Casting Laboratory of Advanced Materials Solidification How to obtain high cohesiveness? By using binders: Clay and water-->green sand mould ·Sodium silicate+CO2(CO2 is hardener）-> Na2SiO3+CO2-->Na2CO3+SiO2(colloidal) Resin-->resin bonded sand mould. 上海充通大￥ SHANGHAI JIAO TONG UNIVERSITY
How to obtain high cohesiveness? By using binders: • Clay and water --> green sand mould • Sodium silicate + CO2 (CO2 is hardener) --> • Na2SiO3 + CO2 -->Na2CO3 + SiO2 (colloidal) • Resin --> resin bonded sand mould. Sand Casting