Multiple choice question for engineering
Set 1
1. The major defects of casting are
a) gas defects
b) shrinkage cavities
c) molding material defects
d) all of the mentioned
Answer
Answer: d [Reason:] Following are the major defects, which are likely to occur in casting:
a) gas defects
b) shrinkage cavities
c) molding material defects
d) pouring metal defects
e) mold shift
2. __________ is 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.
a) gas defects
b) shrinkage cavities
c) molding material defects
d) none of the mentioned
Answer
Answer: a [Reason:] 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
Answer: d [Reason:] 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. ___________ are caused by liquid shrinkage occurring during the solidification of the casting.
a) gas defects
b) shrinkage cavities
c) molding material defects
d) none of the mentioned
Answer
Answer: b [Reason:] 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. The molding material defects are
a) cut and washes
b) metal penetration
c) fusion
d) all of the mentioned
Answer
Answer: d [Reason:] The defects in this category are cuts and washes, metal penetration, fusion, and swell.
6. A __________ is caused when the metal is unable to fill the mold cavity completely and thus leaves unfilled cavities.
a) cold shut
b) mis run
c) all of the mentioned
d) none of the mentioned
Answer
Answer: b [Reason:] 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. A ______________ is caused when two streams while meeting in the mold cavity, do not fuse together properly thus forming a discontinuity in the casting.
a) cold shut
b) mis run
c) all of the mentioned
d) none of the mentioned
Answer
Answer: a [Reason:] 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) None of the mentioned
Answer
Answer: b [Reason:] 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) None of the mentioned
Answer
Answer: c [Reason:] 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) none of the mentioned
Answer
Answer: c [Reason:] 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.
Set 2
1. V or f marked surfaces on a particular casting indicates
a) Camber allowance
b) Machining allowance
c) Draft allowance
d) Shrinkage allowance
Answer
Answer: b [Reason:] Surfaces of castings required to be machined, are made to dimensions more than that indicated on the working drawings. The extra amount of material provided on the surfaces is called machine finish allowance and V or f is indicated on these surfaces.
2. Shrinkage allowance is the amount the pattern must be made ____________ the casting.
a) larger than
b) smaller than
c) same as
d) equal to
Answer
Answer: a [Reason:] Shrinkage allowance is a correction for solidification shrinkage of metal and its contraction during cooling. It is larger than the casting to provide space for total contraction.
3. The process of removing unwanted material from the casting is called
a) fettling
b) cleaning
c) finishing
d) blowing
Answer
Answer: a [Reason:] Fettling is the process of removing unwanted material from the casting while cleaning, blowing and finishing are done on casted materials.
4. In the following type of foundry, melting unit as well as balance equipment are installed to the casting of the particular metal
a) jobbing foundry
b) ferrous foundry
c) mass production foundry
d) non-ferrous foundry
Answer
Answer: b [Reason:] A jobbing foundry is one that produces a casting or a small number of castings of a given kind as per order. Mass production foundries have automatic molding, pouring and finishing lines with a little or no manual handling. The melting unit as well as balance equipment in the foundry is installed in ferrous foundry to suit the casting of particular metal.
5. Following is used for making the hollow cavities in the casting
a) chaplet
b) vent rod
c) core
d) chill
Answer
Answer: c [Reason:] For producing casting with internal cavities or passages, cores which are made of sand are utilized. Cores are placed in the mold cavity to form the interior surface of the casting and are removed from the finished part during fettling process.
6. The limitation of oil as a binder is
a) at lower temperature, bond between sand mix and oil becomes strong
b) at higher temperature, bond between sand mix and oil becomes strong
c) should be added in high volumes
d) quickly hardens
Answer
Answer: b [Reason:] At higher temperatures the bond between sand mix and oil becomes hard and brittle there by weakening the sand mix. So, care should be taken about the rate and temperature of baking of oil sands.
7. Cereals is added to the molding sand to improve the following
a) hot strength
b) porosity
c) green strength
d) edge hardness
Answer
Answer: c [Reason:] Cereals are finely ground corn flour and they increase green dry strengths and collapsibility.
8. To improve the surface finish of castings, the following additive is used in the molding sand
a) resins
b) sea coal
c) oils
d) wood flour
Answer
Answer: b [Reason:] Resins produces good bonding strength between the sand grains, oils are used as binders, wood flour is cellulose material used to overcome sand expansion defects and seal coal is finely ground soft coal used for surface finish of castings.
9. To permit escape of gases generated in the mold, following are provided
a) vent holes
b) chills
c) chaplets
d) core print
Answer
Answer: a [Reason:] Chaplets are used to support the cores inside the mold cavity to take care of its own weight and overcome the metallostatic force, core print is used to create openings and various shaped cavities in the castings, and vent hole, a small opening in the mold to facilitate escape of air and gases.
10. Following is used for making the hollow cavities in the casting
a) chaplet
b) vent rod
c) core
d) chill
Answer
Answer: c [Reason:] Chaplets are used to support the cores inside the mold cavity to take care of its own weight and overcome the metallostatic force, core is a separate part of the mold, made of sand and generally baked, which is used to create openings and various shaped cavities in the castings.
Set 3
1. ______________ which typically are made of sand, plaster, ceramics, and similar materials and generally are mixed with various binders.
a) Permanent molds
b) Expendable molds
c) Composite molds
d) None of the mentioned
Answer
Answer: b [Reason:] Expendable molds, which typically are made of sand, plaster, ceramics, and similar materials and generally are mixed with various binders (bonding agents) for improved properties whereas permanent molds, which are made of metals that maintain their strength at high temperatures.
2. _____________ which are made of metals that maintain their strength at high temperatures.
a) Permanent molds
b) Expendable molds
c) Composite molds
d) None of the mentioned
Answer
Answer: a [Reason:] Expendable molds, which typically are made of sand, plaster, ceramics, and similar materials and generally are mixed with various binders (bonding agents) for improved properties whereas permanent molds, which are made of metals that maintain their strength at high temperatures.
3. Metal molds are better heat conductors than expendable ___________ molds.
a) metallic
b) nonmetallic
c) composite
d) none of the mentioned
Answer
Answer: b [Reason:] Metal molds are better heat conductors than expendable nonmetallic molds, hence, the solidifying casting is subjected to a higher rate of cooling, which in turn affects the micro structure and grain size Within the casting.
4. ___________ which are made of two or more different materials combining the advantages of each material.
a) Permanent molds
b) Expendable molds
c) Composite molds
d) none of the mentioned
Answer
Answer: c [Reason:] Composite molds, which are made of two or more different materials (such as sand, graphite, and metal) combining the advantages of each material.
5. The directional solidification in casting can be improved by using
a) chills and riser
b) chills and padding
c) chaplets and padding
d) none of the mentioned
Answer
Answer: d [Reason:] Chills and riser are used in improving directional solidification.
6. In permanent mold casting method
a) molten metal is poured in a metallic mold, retained in the mold long enough for the outer skin to solidify and finally mold is turned over to remove molten metal still in molten condition
b) molten metal is poured and allowed to solidify while the mold is revolving
c) Molten metal is forced into mold under high pressure
d) none of the mentioned
Answer
Answer: d [Reason:] They are used repeatedly and are designed in such a Way that the casting can be removed easily and the mold used for the next casting. Metal molds are better heat conductors than expendable nonmetallic molds hence, the solidifying casting is subjected to a higher rate of cooling, which in turn affects the micro structure and grain size Within the casting.
7. In a _________ the molten metal is poured and allowed to solidify while the mold is revolving.
a) die casting method
b) slush casting method
c) centrifugal casting method
d) none of the mentioned
Answer
Answer: c [Reason:] A casting process in which the molten metal is poured and allowed to solidify while the mold is revolving, is called centrifugal process. The casting produced under this centrifugal force is called centrifugal casting. This process is especially designed for casting of symmetrical shape.
8. In a hot chamber die casting machine
a) melting pot is separate from the machine
b) melting pot is an integral part of the machine
c) melting pot may have any location
d) none of the mentioned
Answer
Answer: b [Reason:] In a hot chamber die casting machine, the melting pot is an integral part of the machine. The molten metal is forced in the die cavity at pressure from 7 to 14 MPa.
9. Cast iron and steel pipes are produced by
a) slush casting
b) investment casting
c) true centrifugal casting
d) none of the mentioned
Answer
Answer: c [Reason:] The method of Cast Iron pipe production used universally today is to form pipes by spinning or centrifugal action. Compared with vertical casting in sand molds, the spun process results in faster production, longer pipes with vastly improved metal qualities, a smoother inner surface and reduced thickness and consequent light weight.
10. Which of the following statement is wrong?
a) The hot chamber die casting machine is used for casting zinc, tin, lead and other low melting alloys.
b) The cold chamber die casting machine is used for casting aluminum, magnesium, copper base alloys and other high melting alloys.
c) The castings produced by centrifugal casting method have open and coarse grained structure.
d) None of the mentioned
Answer
Answer: c [Reason:] The casting produced by centrifugal casting process have dense and fine grained structure.
11. In a cold chamber die casting machine, only non-ferrous alloys with ___________ are casted.
a) low melting temperature
b) high melting temperature
c) all of the mentioned
d) none of the mentioned
Answer
Answer: b [Reason:] In a cold chamber die casting machine , the melting pot is usually separate from the machine and the molten metal is not transferred to injection mechanism by ladle. The pressure on the casting metal may vary from 21 to 210 MPa and in same cases may reach 700 MPa.
12. The centrifugal casting method, is used for casting articles of
a) symmetrical shape about vertical axis
b) symmetrical shape about horizontal axis
c) irregular shape
d) none of the mentioned
Answer
Answer: a [Reason:] The centrifugal casting method, is used for casting articles of symmetrical shape about vertical axis.
Set 4
1. Grains created when a metal solidifies rather slowly in the presence of a steep temperature gradient fall in the category of
a) equiaxed grains
b) columnar grains
c) all of the mentioned
d) none of the mentioned
Answer
Answer: b [Reason:] Columnar grains are long, thin, coarse grains created when a metal solidifies rather slowly in the presence of a steep temperature gradient. Relatively few nuclei are available when columnar grains are produced.
2. Vacancies are
a) planer defects
b) line defects
c) point defects
d) volume defects
Answer
Answer: c [Reason:] The simplest point defects is the vacancy, an atom site from which an atom is missing.
3. Scanning tunneling microscope is a tool usually used to analyze an image at
a) sub-atomic level
b) atomic level
c) micro level
d) macro level
Answer
Answer: b [Reason:] STM allow mapping of the surface of a material at the atomic level.
4. Examples of line defect are
a) vacancies
b) dislocations
c) twins
d) stacking faults
Answer
Answer: b [Reason:] Line imperfections, or dislocations, in crystalline solids are defects that cause lattice distortion centered around a line.
5. A mixture of a metal(s) and a non-metal(s) is called
a) composite
b) alloy
c) dislocation
d) none of the mentioned
Answer
Answer: b
6. If there are 930 grains per mm2 on a photomicrograph of a metal at 2X, what is the ASTM grain size number of the metal?
a) 6
b) 7
c) 7.92
d) 8.91
Answer
Answer: d [Reason:] If there are 930 grains per mm2 at 2X, then at 1X we will have
N‘ = (2/1)2 (930 grains/mm2) = 3720
therefore, N = N‘/15.5 = 3720/15.5 = 240
240 = 2n-2
log 240 = (n-1)(log 2)
2.380 = (n-1)(0.301)
n = 8.91.
7. An ASTM grain size determination is being made from a photomicrograph of a metal at a magnification of 1X. What is the ASTM grain size number of the metal if there are 992 grains per square mm?
a) 6
b) 7
c) 7.92
d) 8.91
Answer
Answer: b [Reason:] N = 2n-1
where, N = no of grains per square inch at 100X
n = ASTM grain size number
and N is obtained using the following expression:
N = N‘/15.5 where N‘ = no. of grains per square mm at 1X
Thus, N = 992/15.5 = 64
or, 64 = 2n-1
log 64 = (n-1)(log 2)
n = 7.
8. Risers are also called
a) spure
b) runners
c) feeders
d) none of the mentioned
Answer
Answer: c [Reason:] Risers also called feeders serve as reservoirs of molten metal to supply any molten metal necessary to prevent porosity due to shrinkage during solidification.
9. In a free falling liquid, the cross sectional area of the stream
a) increases
b) decreases
c) remains constant
d) none of the mentioned
Answer
Answer: b [Reason:] In a free falling liquid, the cross sectional area of the stream decreases as the liquid gains velocity downward.
10. If the pouring basin has a much larger cross sectional area than the sprue bottom, then the velocity of the molten metal is
a) low
b) high
c) normal
d) none of the mentioned
Answer
Answer: a [Reason:] The molten metal flows through a sprue to a runner and a gate and fills the mold cavity. If the pouring basin has a much larger cross sectional area than the sprue bottom, then the velocity of the molten metal at the top of the pouring basin is very low and can be taken to be zero.
Set 5
1. Maximum deviation in size of shaft or hole is known as
a) Tolerance
b) Fundamental deviation
c) Clearance
d) Interference
Answer
Answer: a [Reason:] Tolerance is the maximum deviation in size of shaft or hole.
2. Nearest deviation between hole and shaft from the basic value is known as
a) Tolerance
b) Fundamental deviation
c) Clearance
d) Interference
Answer
Answer: b [Reason:] Tolerance is the maximum deviation in size of shaft or hole.
3. When size of smallest hole is more than size of biggest shaft then it is
a) Clearance fit
b) Interference fit
c) Transition fit
d) None of the mentioned
Answer
Answer: a [Reason:] When size of smallest hole is more than size of biggest shaft then it is clearance fit.
4. Value of minimum clearance is given by
a) Size of smallest hole – size of biggest shaft
b) Size of smallest hole + size of biggest hole
c) Size of smallest shaft – size of biggest shaft
d) None of the mentioned
Answer
Answer: a [Reason:] Minimum clearance is the difference between size of smallest hole and size of biggest shaft.
5. Value of maximum clearance is given by
a) Size of smallest hole – size of biggest hole
b) Size of smallest shaft + size of biggest hole
c) Size of smallest shaft – size of biggest shaft
d) None of the mentioned
Answer
Answer: b [Reason:] Maximum clearance is given by sum of size of biggest hole and smallest shaft.
6. When size of smallest shaft is more than size of biggest hole then it is
a) Clearance fit
b) Interference fit
c) Transition fit
d) None of the mentioned
Answer
Answer: b [Reason:] When size of smallest shaft is more than size of biggest hole then it is interference fit.
7. Value of maximum Interference is given by
a) Size of smallest hole – size of biggest shaft
b) Largest of shaft size hole – smallest hole size
c) Size of smallest shaft – size of biggest shaft
d) None of the mentioned
Answer
Answer: b [Reason:] Maximum Interference is the difference between size of largest haft size and smallest hole size.
8. Value of minimum interference is given by
a) Size of smallest hole – size of biggest hole
b) Size of smallest shaft + size of biggest hole
c) Size of smallest shaft – size of biggest hole
d) None of the mentioned
Answer
Answer: c [Reason:] Minimum interference is the difference between size of smallest shaft and size of biggest hole.
9. For manufacturing of certain amount of hole, maximum hole size was found to be 50.14 mm and minimum hole size was found to be 49.98. Tolerance in mm will be
a) 0.12
b) 0.13
c) 0.16
d) 0.20
Answer
Answer: c [Reason:] Tolerance is the maximum deviation in size of shaft or hole.
10. In manufacturing of hole and shaft, maximum shaft diameter was 49.88 mm and minimum hole diameter was found to be 49.94 mm. It is a
a) Clearance fit
b) Interference fit
c) Transition fit
d) None of the mentioned
Answer
Answer: a [Reason:] When size of smallest hole is more than size of biggest shaft then it is clearance fit.