"Chill casting uses a massive metal mould with a large thermal capacity
or a water cooled metal mould so that Bi
<< 1. "
www.heacademy.ac.uk/assets/documents/subjects/materials/Sol... &ei=HBMNUI6hKqGH0AXL7dTRCg&usg=AFQjCNFLf6uLMSAPfRnZ7qFm29pATJl91Q&cad=rja...

The above website address may not work, but ref can be found by googling an extract.

http://en.wikipedia.org/wiki/Chill_(casting)
"DC (Direct Chill) Casting
A continuous method of making ingots or billets for sheet or extrusion by pouring the metal into a short mold. The base of the mold is a platform that is gradually lowered while the metal solidifies, the frozen shell of metal acting as a retainer for the liquid metal below the wall of the mold. The ingot is usually cooled by the impingement of
water directly on the mold or on the walls of the solid metal as it is lowered. The length of the ingot is limited by the depth to which the platform can be lowered; therefore, it is often called semicontinuous casting."