Casting Defects and Causes: Master the Fundamentals

Question 1

Identify the casting defect characterized by an internal void or cavity, often resulting from insufficient molten metal filling the mold:

Accepted Answer

Shrinkage Cavity

Answer

Misrun

Answer

Hot Tear

Answer

Gas Porosity

Question 2

Which of the following casting defects is caused by uneven cooling, leading to internal stresses and potential cracking?

Accepted Answer

Hot Tear

Answer

Sand Inclusion

Answer

Blowhole

Question 3

Identify the casting defect that involves the presence of foreign material, such as sand grains, embedded within the casting:

Accepted Answer

Sand Inclusion

Answer

Cold Shut

Answer

Shrinkage Cavity

Answer

Gas Porosity

Question 4

Which of the following is NOT a common cause of gas porosity in castings?

Accepted Answer

Proper mold venting

Answer

Decomposition of mold materials

Answer

Rapid cooling of the casting

Answer

Excessive moisture in the mold

Question 5

Identify the casting defect that occurs due to the failure of two streams of molten metal to fuse together properly, leaving a discontinuity in the casting:

Accepted Answer

Cold Shut

Answer

Sand Inclusion

Answer

Hot Tear

Answer

Misrun

Question 6

Which of the following casting defects is most likely to result from incomplete filling of the mold cavity?

Accepted Answer

Misrun

Answer

Cold Shut

Answer

Hot Tear

Answer

Blowhole

Question 7

Which of the following actions is LEAST effective in reducing the occurrence of hot tears in castings?

Accepted Answer

Increasing the pouring temperature of the molten metal.

Answer

Employing a more uniform mold design.

Answer

Using a mold material with higher thermal conductivity.

Question 8

Identify the casting defect characterized by the presence of small, round voids throughout the casting, often caused by trapped gases:

Accepted Answer

Gas Porosity

Answer

Shrinkage Cavity

Answer

Sand Inclusion

Answer

Blowhole

Question 9

Which of the following is NOT a typical consequence of casting defects?

Accepted Answer

Increased casting strength.

Answer

Potential safety hazards

Answer

Reduced casting lifespan.

Answer

Increased machining costs.

Question 10

Which of the following defects is NOT directly related to shrinkage during the solidification of a casting?

Accepted Answer

Cold shut

Answer

Hot tear

Answer

Porosity

Answer

Shrinkage cavity

Question 11

Gas porosity in castings is primarily caused by:

Accepted Answer

Trapped gases within the molten metal during solidification.

Answer

Improper mold venting.

Answer

Rapid cooling of the molten metal.

Answer

Low pouring temperature of the molten metal.

Question 12

Hot tearing in castings typically results in:

Accepted Answer

Cracks in the casting.

Answer

Cold shuts.

Answer

Porosity.

Answer

Shrinkage cavities.

Question 13

To prevent misruns in castings, it is most effective to:

Accepted Answer

Increase the fluidity of the molten metal.

Answer

Reduce the pouring temperature.

Answer

Use a smaller gating system.

Answer

Increase the mold temperature.

Question 14

A feathered edge defect in castings typically occurs when:

Accepted Answer

Molten metal flows too rapidly into the mold cavity.

Answer

The metal solidifies too slowly within the mold.

Answer

The mold is not adequately vented.

Answer

The pouring temperature of the molten metal is too high.

Question 15

Which of the following casting defects is primarily a metallurgical issue related to the metal's microstructure?

Accepted Answer

Grain boundary liquation

Answer

Hot tear

Answer

Gas porosity

Answer

Cold shut

Question 16

In casting processes, chills are primarily used to prevent:

Accepted Answer

Shrinkage defects.

Answer

Feathered edges.

Answer

Hot tears.

Answer

Gas porosity.

Question 17

Non-destructive testing methods in casting are mainly used to:

Accepted Answer

Detect defects within a casting without causing damage.

Answer

Determine the exact mechanical properties of the casting.

Answer

Measure the precise dimensions of the casting.

Question 18

Slag inclusions in castings are often caused by:

Accepted Answer

Insufficient cleaning of the molten metal before pouring.

Answer

Low fluidity of the molten metal.

Answer

High pouring temperature of the molten metal.

Answer

Improper design of the mold cavity.

Question 19

Which of the following casting defects is characterized by rounded edges and a smooth, concave surface, often appearing in thicker sections of the casting?

Accepted Answer

Shrinkage Cavity

Answer

Misrun

Answer

Gas Porosity

Answer

Sand Inclusion

Question 20

What is the primary cause of gas porosity in castings?

Accepted Answer

Trapped gases within the molten metal during solidification

Answer

Insufficient pouring temperature of the molten metal

Answer

Use of incorrect sand mold material

Question 21

Which of the following is a common remedy for preventing sand inclusion defects in sand castings?

Accepted Answer

Applying a suitable mold coating

Answer

Slowing down the cooling rate

Answer

Increasing the pouring temperature

Answer

Using a larger gate size

Question 22

A misrun defect occurs when:

Accepted Answer

The molten metal solidifies before completely filling the mold cavity

Answer

The mold material reacts chemically with the molten metal

Answer

The casting experiences uneven cooling rates

Question 23

Hot tears in castings are primarily caused by:

Accepted Answer

Restrained contraction during cooling

Answer

Presence of impurities in the molten metal

Answer

Improper pattern design

Answer

Excessive pouring temperature

Question 24

Which of these defects is most likely to be found near the surface of a casting?

Accepted Answer

Cold shut

Answer

Shrinkage cavity

Answer

Microporosity

Question 25

Dross defects are primarily associated with the presence of:

Accepted Answer

Oxides and other impurities in the molten metal

Answer

Moisture in the mold material

Answer

Turbulent flow during pouring

Question 26

What is the purpose of a riser in casting?

Accepted Answer

To compensate for shrinkage during solidification

Answer

To provide a pathway for trapped gases to escape

Answer

To prevent sand inclusion defects

Answer

To ensure uniform mold filling

Question 27

Which casting process is generally considered to have the least susceptibility to gas porosity?

Accepted Answer

Vacuum Casting

Answer

Die Casting

Answer

Sand Casting

Answer

Investment Casting

Question 28

A casting defect is identified as a linear discontinuity on the surface. Which of the following is the most likely cause?

Accepted Answer

Misalignment of mold halves

Answer

High gas content in the molten metal

Answer

Presence of foreign particles in the mold

Answer

Insufficient pouring temperature

Question 29

An internal void present in a casting caused by the entrapment of gases is called:

Accepted Answer

Blowhole

Answer

Shrinkage cavity

Answer

Cold shut

Answer

Hot tear

Question 30

Which of the following is NOT a cause of shrinkage cavity defects?

Accepted Answer

Slow cooling rate

Answer

Poor mold design

Answer

High pouring temperature

Answer

Insufficient metal feeding

Question 31

A surface crack in a casting caused by unequal cooling rates is known as:

Accepted Answer

Hot tear

Answer

Slag inclusion

Answer

Blowhole

Answer

Cold shut

Question 32

Which of the following casting defects is caused by the merging of two incompletely fused metal streams?

Accepted Answer

Cold shut

Answer

Hot tear

Answer

Slag inclusion

Question 33

Solidification of molten metal around non-metallic particles in a casting can lead to:

Accepted Answer

Slag inclusion

Answer

Blowhole

Answer

Hot tear

Question 34

What is the primary cause of misruns?

Accepted Answer

Insufficient metal flow

Answer

Incorrect gating design

Answer

Rapid cooling

Answer

High pouring temperature

Question 35

Which of the following is a consequence of casting defects?

Accepted Answer

Reduced mechanical properties

Answer

Enhanced durability

Answer

Improved surface finish

Question 36

To prevent blowholes, which measure should be taken?

Accepted Answer

Use degassing agents

Answer

Reduce cooling rate

Answer

Enlarge the sprue size

Answer

Increase pouring temperature

Question 37

Which casting process is particularly susceptible to cold shuts?

Accepted Answer

Sand casting

Answer

Centrifugal casting

Answer

Die casting

Answer

Investment casting

Question 38

The recommended action to minimize hot tears is to:

Accepted Answer

Slow down cooling rate

Answer

Increase pouring temperature

Answer

Enlarge the risers

Answer

Use chills

Question 39

Which of the following is NOT a common type of casting defect?

Accepted Answer

Corrosion

Answer

Gas porosity

Answer

Cold shut

Answer

Shrinkage

Question 40

What is the primary cause of shrinkage defects in castings?

Accepted Answer

Solidification of molten metal from the outer surface inwards

Answer

Presence of impurities in the molten metal

Answer

Rapid cooling of the molten metal

Question 41

Which of the following is a preventative measure for gas porosity defects?

Accepted Answer

Proper degassing of the molten metal

Answer

Applying vacuum to the mold cavity

Answer

Using higher pouring temperatures

Answer

Increasing the cooling rate of the casting

Question 42

What is the main cause of cold shut defects?

Accepted Answer

Premature freezing of the metal stream during pouring

Answer

Excessive mold moisture

Answer

Insufficient clamping force on the mold

Question 43

Which of the following casting processes is most susceptible to hot tears?

Accepted Answer

Sand casting

Answer

Permanent mold casting

Answer

Die casting

Answer

Investment casting

Question 44

What is the purpose of a riser in casting?

Accepted Answer

To provide a reservoir of molten metal to feed the casting as it solidifies

Answer

To enhance the cooling rate of the casting

Answer

To create a vacuum in the mold cavity

Question 45

Which of the following factors does NOT affect the severity of shrinkage defects in castings?

Accepted Answer

Mold material

Answer

Casting geometry

Answer

Presence of alloying elements

Answer

Solidification rate

Question 46

What is the main purpose of a chill in casting?

Accepted Answer

To increase the cooling rate of the casting in a specific area

Answer

To reduce the risk of hot tears

Answer

To improve the surface finish of the casting

Question 47

Which of the following is a common cause of misruns in castings?

Accepted Answer

Insufficient metal fluidity

Answer

Improper pouring technique

Answer

Premature solidification of the metal stream

Answer

Excessive mold resistance

Question 48

What is the primary role of a mold release agent in casting?

Accepted Answer

To prevent the casting from sticking to the mold

Answer

To improve the fluidity of the molten metal

Answer

To enhance the surface finish of the casting

Answer

To reduce the cooling rate of the casting