ABSTRACT
The vacuum casting process uses dry silica sand that contains no moisture or binders. A second sheet of plastic is placed on top of the sand and a vacuum applied to draw out the air and strengthen the unbonded sand. When the metal solidifies, the vacuum is turned off and the sand runs out freely, releasing the casting. Pattern life is unlimited as the sand does not touch it. Grooves are provided in the top and bottom rolls to give the various reductions and the final shape where appropriate. Drawing is mainly used in the production of wire, rod and bar. The rod is then pulled through the die to give the necessary reduction in section. Hand tools are used to manipulate the hot metal to give changes in section and changes in shape by bending and twisting. Due to the hand operation, it is not possible to achieve high degrees of accuracy or extreme complexity of shape.
