Metal Casting Processes Lecture Notes

Flashcards covering vocabulary and concepts of sand casting, die casting, and investment casting as discussed in the lecture transcript.

Thermal sand reclaim oven

A machinery used after sand casting where the mold spends six hours to break down the glue so the sand falls away while the heat strengthens the metal.

Risers

Extra reservoirs of metal that feed the mold cavity to compensate for the $7\%$ shrinkage that occurs when liquid aluminum solidifies.

Automated vision system

An inspection technology used at the end of the production line to ensure engine blocks have no defects.

Die casting

A manufacturing process that uses a permanent steel die instead of a sand mold, limited to metals with melting points lower than steel.

High pressure die casting

A method where liquid metal is injected into a steel die at high pressures and velocities to create very thin parts in fractions of a second.

Porosity

A mechanical defect often found in high pressure die cast parts caused by trapped air or turbulence during the rapid metal injection.

Low pressure die casting

A process where the mold is filled slowly at controlled rates from underneath, resulting in low turbulence and very high quality parts like rim wheels.

Investment casting

A process used for high melting point metals involving a wax pattern coated in ceramic slurry that is later melted out to leave a mold cavity.

Slurry

A liquid mixture containing ceramic powder or flour used to coat wax patterns layer by layer in investment casting.

Sintering

The thermal process where ceramic particles in an investment mold bond together in an oven to create a rigid, strong mold.

Sprue

The part of a casting mold shaped like a funnel that directs the liquid metal into the system.

Runners

The channels within a mold that carry the molten metal to the various parts of the casting.

Drag

The technical term for the bottom part of a two-part casting mold.

Equiaxed grains

Small, round grains that are consistent throughout a part, resulting in isotropic (non-directional) mechanical properties.

Columnar grains

Grains that grow directionally from the edge of the mold wall inwards during solidification.

Shrinkage porosity

A defect formed when a metal cools and contracts, leaving voids or holes if fresh liquid metal is not supplied by a riser.

Hydrogen

The specific gas that causes high porosity in aluminum casting because it is soluble in the liquid phase but forms bubbles when the metal solidifies.