Manufacturing Engineering Multiple Choice Questions on “Metal Casting Defects”.
1. The major defects of casting are __________
a) gas defects
b) shrinkage cavities
c) molding material defects
d) all of the mentioned
Answer: d
Clarification: Following are the major defects, which are likely to occur in casting:
i) gas defects
ii) shrinkage cavities
iii) molding material defects
iv) pouring metal defects
v) mold shift.
2. The defects caused by trapping a gas in molten metal or by mold gases while pouring the melt is known as?
a) Gas defects
b) Shrinkage cavities
c) Molding material defects
d) Pouring defects
Answer: a
Clarification: Shrinkage cavities are caused by liquid shrinkage occurring during the solidification of the casting while gas defects are a condition existing in a casting caused by the trapping of gas in the molten metal or by mold gases evolved during the pouring of the casting.
3. The causes of gas defects are ___________
a) metal contains gas
b) mold is too hot
c) poor mold burnout
d) all of the mentioned
Answer: d
Clarification: The lower gas-passing tendency of the mold, which may be due to lower venting, lower permeability of the mold or improper design of the casting. The lower permeability is caused by finer grain size of the sand, high percentage of clay in mold mixture, and excessive moisture present in the mold.
Metal contains gas
Mold is too hot
Poor mold burnout.
4. The defects caused by liquid shrinkage during the solidification of the casting?
a) gas defects
b) shrinkage cavities
c) molding material defects
d) hot tears
Answer: b
Clarification: Shrinkage cavities are caused by liquid shrinkage occurring during the solidification of the casting while gas defects are a condition existing in a casting caused by the trapping of gas in the molten metal or by mold gases evolved during the pouring of the casting.
5. In casting, which of the following are not material defects?
a) cut and washes
b) metal penetration
c) fusion
d) hot tears
Answer: d
Clarification: The defects in this category are cuts and washes, metal penetration, fusion, and swell.
6. The defect caused when the melt is unable to fill the mold cavity completely and thus leaves cavities is termed as?
a) cold shut
b) misrun
c) hot tear
d) porosity
Answer: b
Clarification: A mis-run is caused when the metal is unable to fill the mold cavity completely and thus leaves unfilled cavities and a cold shut is caused when two streams while meeting in the mold cavity, do not fuse together properly thus forming a discontinuity in the casting.
7. The defect caused when two streams do not fuse together (while melting), thus forming discontinuity in casting is termed as?
a) cold shut
b) misrun
c) hot tear
d) porosity
Answer: a
Clarification: A mis-run is caused when the metal is unable to fill the mold cavity completely and thus leaves unfilled cavities and a cold shut is caused when two streams while meeting in the mold cavity, do not fuse together properly thus forming a discontinuity in the casting.
8. A casting defect which occurs near the ingates as rough lumps on the surface of a casting is?
a) Shift
b) Sand wash
c) Swell
d) Hot tear
Answer: b
Clarification: Swell is caused under the influence of metallostatic forces, the mold wall may move back causing a swell in the dimension of the casting whereas Sand wash is a casting defect which occurs near the ingates as rough lumps on the surface of a casting.
9. A casting defect which occurs due to improper venting of sand is known as?
a) Cold shuts
b) Blow holes
c) Shift
d) Hot tear
Answer: c
Clarification: The mold shift defect occurs when cope and drag or molding boxes have not been properly aligned and a cold shut is caused when two streams while meeting in the mold cavity.
10. Scabs are casting defects which?
a) result in a mismatch of the top and bottom parts of a casting
b) result near the ingates as rough lumps on the surface of a casting
c) occur as rough and irregular projections on the surface of the casting
d) occur as smooth and regular projections on the surface of the casting
Answer: c
Clarification: A casting defect which occurs near the ingates as rough lumps on the surface of a casting is sand wash and scabs are casting defects which occur as rough and irregular projections on the surface of the casting.