Chapter 5 Flashcards
Capabilities and Advantages of Casting (4)
Complex geometric shapes
External and internal shapes
Very large parts
Mass production
Disadvantages of Casting (4)
Limitation on mech properties
Poor dimensional accuracy
safety hazard
environmental problems
Name of factory equipped to make molds
foundry
Name parts of mold. Main parts.
Pouring cup, downsprue, runner, riser then cavity.
Parting line separates Cope and drag
Name expendable mold materials
Sand, plaster
Permanent or expendable $$$
Permanent are more economic in high production operations
Upper half of mold
Cope
What factors determine success in molds (3)
Pouring rate
Pouring temperature
Turbulence
How does a pure metal solidify
Constant temp equal to its melting point.
Grains are randomly oriented at walls and then upside down Y toward the center
How does an alloy solidify
Freeze over a temperature range.
Small grains at walls and center. Then grains create upside down Y with small grains in the middle.
Chvorinov’s Rule
Tts = Cm(V/A)^n=2
Total solidification time is equal to the mold constant * Volume of casting / surface area of casting to the 2.
Mold constant depends on
Mold material
Thermal properties of casting metal
Pouring temp relative to melting temp
Exception to shrinkage
Cast iron with High C content.
