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Manufacturing Process > Permanent Mould Casting > Flashcards

Permanent Mould Casting Flashcards

1
Q

Why is the mold pre-heated in the mold preparation process?

A

To allow better metal flow and reduce defects.

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2
Q

What is applied to the mold cavity surfaces to facilitate part removal and increase mold lifetime?

A

A ceramic coating.

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3
Q

What materials are typically used to make cores for complex casting features?

A

Cores are typically made from iron or steel, but expendable sand cores may also be used.

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4
Q

How many castings can be manufactured from a mold depending on the alloy and casting complexity?

A

Between 100 to 250,000 castings.

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5
Q

What factors determine the selection of mold material?

A

Pouring temperature, size of the casting, and frequency of the casting cycle.

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6
Q

What material is most commonly used for casting due to its fine grain?

A

Fine-grained grey cast iron.

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7
Q

What materials are used for casting large volumes and large parts?

A

Alloy cast iron, C20 steel, and alloy steels.

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8
Q

For small-volume production from aluminum and magnesium, which type of molds can be used?

A

Graphite molds.

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9
Q

How does the die life change with higher melting temperature alloys?

A

Die life is shorter for higher melting temperature alloys such as copper or grey cast iron.

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10
Q

What process is called “semi-permanent molding”?

A

When sand cores are used in permanent mold casting.

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11
Q

Through what is molten metal poured into the mold?

A

Through a sprue at the top of the mold.

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12
Q

What happens after the molten metal solidifies in the mold?

A

The two mold halves are opened and the casting is removed.

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13
Q

What is the purpose of trimming in casting?

A

To cut away the excess material that solidified in the runner system and sprue during cooling.

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14
Q

What is the typical range of castings manufactured depending on the alloy and casting complexity?

A

Between 100 to 250,000 castings.

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15
Q

What factors influence the selection of material for casting?

A

Pouring temperature, size of the casting, and frequency of the casting cycle.

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16
Q

What is the most commonly used material for casting?

A

Fine-grained grey cast iron.

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17
Q

What materials are typically used for large volumes and large parts in casting?

A

Alloy cast iron, C20 steel, and alloy steels.

18
Q

What type of molds may be used for small-volume production from aluminum and magnesium?

A

Graphite molds.

19
Q

Why is the immediate withdrawal of the core important after solidification?

A

To prevent damage to the casting and ensure proper mold operation.

20
Q

What can be included in a metallic mold to enhance its life?

A

A cooling system.

21
Q

What is a refractory material coating, and what is its purpose?

A

A mixture of sodium silicate, kaolin clay, soapstone, and talc applied up to 0.8mm thick to enhance mold life.

22
Q

What are the advantages of the casting process?

A

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.

23
Q

How does die life vary with higher melting temperature alloys?

A

Die life is shorter for higher melting temperature alloys such as copper or grey cast iron.

24
Q

What materials can cores be made from in permanent mold casting?

A

Cores can be made out of metal or sand.

25
Q

What is the process called when sand cores are used in permanent mold casting?

A

Semi-permanent molding.

26
Q

What is one limitation of permanent mold casting regarding the size of castings?

A

The maximum size of the casting that can be produced is limited.

27
Q

Why is the cost of die casting a limitation?

A

The cost of the die is very high.

28
Q

Are all materials suitable for permanent mold casting?

A

No, not all materials are suited for permanent mold casting.

29
Q

What are some applications of permanent mold casting?

A

Automobile pistons

Stators
Gear blanks
Connecting rods
Cylinder blocks
Aircraft fittings

30
Q

What is die casting or pressure die casting?

A

A process that involves injecting molten metal at high pressure into a metallic die.

31
Q

What advantages does die casting provide due to high pressure?

A

It allows for the production of narrow sections, complex shapes, and fine surface details.

32
Q

What are the two parts of a die in die casting?

A
  1. Stationary half (cover die)
  2. Moving half (ejector die)
33
Q

What are the two types of die casting machines?

A
  1. Hot-chamber die casting machine
  2. Cold-chamber die casting machine
34
Q

What are some applications of die casting?

A

Carburetors

Crank cases
Magnetos
Handlebar housings
Parts of scooters
Parts of motorcycles and mopeds
Zip fasteners
Decorative items

35
Q

What is a common problem in pressure die casting?

A

The air left in the cavity when the die is closed.

36
Q

What is the purpose of vacuum die casting?

A

To evacuate the air from the die.

37
Q

What are the benefits of using vacuum die casting?

A

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)

38
Q

What types of alloys are typically used in vacuum die casting?

A

Aluminum and magnesium-based alloys.

39
Q

What is used to force the molten metal into the die during vacuum die casting?

A

Compressed gas.

40
Q

What is the typical pressure range used in vacuum die casting?

A

From 0.3 to 1.5 bars.

41
Q

What type of mold is used in vacuum die casting?

A

A permanent mold.

Manufacturing Process (5 decks)

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