Fichas
Fundamentals of Casting
Fichas del conjunto (12)
- 1Key steps in casting1) Melt the metal
2) Pour into a mould
3) Let molten metal freeze
4) Remove from mould - 2Advantages of casting- Creates relatively complex geometries
- Can create both internal and external shapes
- Produces very larges shapes
- Can be suited to mass production (if the geometry is less complex) - 3Disadvantages of casting- Material limits mechanical capabilities
- Poor dimensional accuracy and surface finish
- Excess material
- Safety issues - 4What are the two forms of mould?Open mould and closed mould
- 5Closed mould castingHas a complex geometry, requires a gating system leading into the cavity.
- 6Features in a closed mould casting- Risers: A reservoir built to prevent cavities due to shrinkage
- Core: Used to create an internal cavity
- Runners: Connected channels that transport the molten metal - 7What is an expendable mould process?The mould must be destroyed in order to remove the casting
- 8What is a permanent mould process?-One where the mould can be reused many times
- Open moulds used - 9How does volume to surface ratio affect the casting?A casting with a higher volume-to-surface area ratio cools and
solidifies more slowly than one with a lower ratio - 10How do you minimise the effects of shrinkage?Design the
riser to have a larger volume-to-surface area ratio so that the main
casting solidifies first - 11Solidification shrinkageShrinkage of a cylindrical casting during solidification and cooling.
Causes a reduction in level of the casting - 12Directional solidificationThe regions most distant from the molten metal should freeze first. To do this Locate sections of the casting with lower V/A ratios away from
the riser, so freezing occurs first in these regions.