• The selection of a casting/molding method is a critical production decision, because different molding methods have trade-offs between initial cost, tool life, surface finish, dimensional tolerances and production cycle time.

• In considering molding methods, the Corvette brake pedal had two important production factors --

-   Moderate rate (35,000/year), long term (10 year) production
-   Stringent dimensional and surface finish requirements.

• Three casting/molding options were considered --

A green sand mold is formed by packing a mixture of sand, clay and water around a pattern to form a mold cavity. The pattern is removed and molten metal is poured into  the mold cavity  through the sprue.

A permanent mold consists of two steel/iron halves in which the mold cavity has been machined. For gravity feed, molten metal is poured in the mold cavity through the in-gate

A low pressure permanent mold uses 3-15 psi of gas pressure to push the molten metal from a furnace up into the cavity of the two-piece steel mold.

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