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:
“The law is equal before all of us; but we are not all equal before the law. Virtually there is one law for the rich and another for the poor, one law for the cunning and another for the simple, one law for the forceful and another for the feeble, one law for the ignorant and another for the learned, one law for the brave and another for the timid, and within family limits one law for the parent and no law at all for the child.”
—George Bernard Shaw (1856–1950)
“We are in the process of creating what deserves to be called the idiot culture. Not an idiot sub-culture, which every society has bubbling beneath the surface and which can provide harmless fun; but the culture itself. For the first time, the weird and the stupid and the coarse are becoming our cultural norm, even our cultural ideal.”
—Carl Bernstein (b. 1944)