Page 16 - Curriculum Visions Dynamic Book
P. 16
(Below and inset) The brass fitting below (part of a central heating control valve) is
cast. The telltale features are slightly rough surfaces (A) and line marking where the halves of the die once met (B).
For metals such as iron with high melting points the mould is often made of fine silica sand. It will not react chemically with the liquid metal or be distorted by the heat. For metals such as zinc and copper with lower melting points moulds can be made from other metals, such as iron.
Casting in sand leaves a rough surface finish, and further work may have to be done to get a smooth surface.
B
The steel strand is being continuously cut at the end of its run.
A
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