Permanent Mould Casting Flashcards
Why is the mold pre-heated in the mold preparation process?
To allow better metal flow and reduce defects.
What is applied to the mold cavity surfaces to facilitate part removal and increase mold lifetime?
A ceramic coating.
What materials are typically used to make cores for complex casting features?
Cores are typically made from iron or steel, but expendable sand cores may also be used.
How many castings can be manufactured from a mold depending on the alloy and casting complexity?
Between 100 to 250,000 castings.
What factors determine the selection of mold material?
Pouring temperature, size of the casting, and frequency of the casting cycle.
What material is most commonly used for casting due to its fine grain?
Fine-grained grey cast iron.
What materials are used for casting large volumes and large parts?
Alloy cast iron, C20 steel, and alloy steels.
For small-volume production from aluminum and magnesium, which type of molds can be used?
Graphite molds.
How does the die life change with higher melting temperature alloys?
Die life is shorter for higher melting temperature alloys such as copper or grey cast iron.
What process is called “semi-permanent molding”?
When sand cores are used in permanent mold casting.
Through what is molten metal poured into the mold?
Through a sprue at the top of the mold.
What happens after the molten metal solidifies in the mold?
The two mold halves are opened and the casting is removed.
What is the purpose of trimming in casting?
To cut away the excess material that solidified in the runner system and sprue during cooling.
What is the typical range of castings manufactured depending on the alloy and casting complexity?
Between 100 to 250,000 castings.
What factors influence the selection of material for casting?
Pouring temperature, size of the casting, and frequency of the casting cycle.
What is the most commonly used material for casting?
Fine-grained grey cast iron.
What materials are typically used for large volumes and large parts in casting?
Alloy cast iron, C20 steel, and alloy steels.
What type of molds may be used for small-volume production from aluminum and magnesium?
Graphite molds.
Why is the immediate withdrawal of the core important after solidification?
To prevent damage to the casting and ensure proper mold operation.
What can be included in a metallic mold to enhance its life?
A cooling system.
What is a refractory material coating, and what is its purpose?
A mixture of sodium silicate, kaolin clay, soapstone, and talc applied up to 0.8mm thick to enhance mold life.
What are the advantages of the casting process?
Produces fine-grained castings with superior mechanical properties.
Provides a very good surface finish.
Achieves closed dimensional tolerances.
Economical for large-scale production.
Produces small core holes compared to sand casting.
Allows for easy insertion of components.
How does die life vary with higher melting temperature alloys?
Die life is shorter for higher melting temperature alloys such as copper or grey cast iron.
What materials can cores be made from in permanent mold casting?
Cores can be made out of metal or sand.
What is the process called when sand cores are used in permanent mold casting?
Semi-permanent molding.
What is one limitation of permanent mold casting regarding the size of castings?
The maximum size of the casting that can be produced is limited.
Why is the cost of die casting a limitation?
The cost of the die is very high.
Are all materials suitable for permanent mold casting?
No, not all materials are suited for permanent mold casting.
What are some applications of permanent mold casting?
Automobile pistons
Stators
Gear blanks
Connecting rods
Cylinder blocks
Aircraft fittings
What is die casting or pressure die casting?
A process that involves injecting molten metal at high pressure into a metallic die.
What advantages does die casting provide due to high pressure?
It allows for the production of narrow sections, complex shapes, and fine surface details.
What are the two parts of a die in die casting?
- Stationary half (cover die)
- Moving half (ejector die)
What are the two types of die casting machines?
- Hot-chamber die casting machine
- Cold-chamber die casting machine
What are some applications of die casting?
Carburetors
Crank cases
Magnetos
Handlebar housings
Parts of scooters
Parts of motorcycles and mopeds
Zip fasteners
Decorative items
What is a common problem in pressure die casting?
The air left in the cavity when the die is closed.
What is the purpose of vacuum die casting?
To evacuate the air from the die.
What are the benefits of using vacuum die casting?
Decreases the fill rate
Parts do not experience any porosity
Parts are exposed to atmospheric air only after solidification
Produces parts with very thin walls (1 to 12 mm)
What types of alloys are typically used in vacuum die casting?
Aluminum and magnesium-based alloys.
What is used to force the molten metal into the die during vacuum die casting?
Compressed gas.
What is the typical pressure range used in vacuum die casting?
From 0.3 to 1.5 bars.
What type of mold is used in vacuum die casting?
A permanent mold.
