The Shaw process, also known as the Osborn-Shaw process, uses a mixture of refractory aggregate, hydrolyzed ethyl silicate, alcohol, and a gelling agent to create a mold. This slurry mixture is poured into a slightly tapered flask and a reusable pattern (i.e. the item used to create the shape of the mold) is used. The slurry hardens almost immediately to a rubbery state (the consistency of vulcanized rubber). The flask and pattern is then removed. Then a torch is used to ignite the mold, which causes most of the volatiles to burn-off and the formation of ceramic microcrazes (microscopic cracks). These cracks are important, because they allow gases to escape while preventing the metal from flowing through; they also ease thermal expansion and contraction during solidification and shrinkage. After the burn-off, the mold is baked at 1,800 °F (980 °C) to remove any remaining volatiles. Prior to pouring metal, the mold is pre-warmed to control shrinkage.
Read more about this topic: Ceramic Mold Casting
Famous quotes containing the words shaw and/or process:
“An Irishman’s heart is nothing but his imagination.”
—George Bernard Shaw (1856–1950)
“Science is a dynamic undertaking directed to lowering the degree of the empiricism involved in solving problems; or, if you prefer, science is a process of fabricating a web of interconnected concepts and conceptual schemes arising from experiments and observations and fruitful of further experiments and observations.”
—James Conant (1893–1978)