Manufacturing Science - Casting
Exam Duration: 45 Mins Total Questions : 20
Process of pouring molten metal under high pressure into mould is called
- (a)
permanent mould casting
- (b)
die casting
- (c)
investment casting
- (d)
centrifugal casting
A cube of side a and a solid has diameter d. They are made from same material. The ratio of their solidification time is
- (a)
a2d2
- (b)
\(\frac { { d }^{ 2 } }{ { a }^{ 2 } } \)
- (c)
\(\frac { { a }^{ 2 } }{ { d }^{ 2 } } \)
- (d)
\(\frac { a }{ d } \)
During cooling, a cubical casting of side 40 mm undergoes 3%, 4% and 5% volume shrinkage during liquid state, phase transition and solid state respectively. The volume compensated from riser is
- (a)
2%
- (b)
8%
- (c)
7%
- (d)
12%
If shrinkage allowance are 0.3 mm/mm, then the internal diameter of the pattern is (given, the cross-sectional area of sprue at the base = 1 cm2, in figure actual size of casting is given)
- (a)
20.6 mm
- (b)
40.6 mm
- (c)
20.12 mm
- (d)
19.4 mm
Time taken to fill the cavity is
- (a)
169.16 s
- (b)
180 s
- (c)
175 s
- (d)
184 s
The area of sprue at the base is 5 cm2. The time taken by sprue to fill the cavity is
- (a)
7.31 s
- (b)
6.32 s6.78
- (c)
6.78 s
- (d)
6.9 s
A sprue for avoiding aspiration to deliver liquid iron at a rate of 20 kg/so The density of iron is 7800 kg/m3. The height of pouring basin is 9 cm and height of sprue is 25 cm. The diameter of sprue base is
- (a)
3.55 cm
- (b)
4.55 cm
- (c)
3.75 cm
- (d)
4.75 cm
Gray cast iron blocks 100 cm x 50 cm x 40 cm are to be cast in sand moulds. Shrinkage allowance pattem making is 1% The ratio of volumes of pattern to that of casting will be
- (a)
1.03
- (b)
1.02
- (c)
1.10
- (d)
1.20
A casting of 50 cm x 40 cm x 10 cm size solidifies in 20 min. The solidification time for 40 cm x 30 cm x 5 cm, casting under similar condition is
- (a)
4 min
- (b)
4.02 min
- (c)
4.01 min
- (d)
3.15 min
For a riser \(\frac{d}{h}\)= 1, it is used to feed a casting 20 cm x 20 cm x 10 cm. Volume shrinkage on solidification is 3% for steel and that the volume of riser is 3 times that dictated by shrinkage considerations alone. The riser diameter or height is
- (a)
14 cm
- (b)
13 cm
- (c)
15 cm
- (d)
17 cm
Draft on pattern for casting is
- (a)
shrinkage allowance
- (b)
taper to facilitate its removal from mould
- (c)
for machining allowance
- (d)
All of the above
In order to facilitate withdrawal of pattern
- (a)
allowances are made on pattern
- (b)
draft is provided on pattern
- (c)
Both (a) and (b)
- (d)
All of the above
Cores are used to
- (a)
make desired recess in castings
- (b)
support loose pieces
- (c)
remove pattern easily
- (d)
All of the above
Shrinkage allowance is made up by
- (a)
adding to external and internal dimensions
- (b)
subtracting from external and internal dimensions
- (c)
Both (a) and (b)
- (d)
adding to external dimensions and subtracting from internal dimensions
The purpose of chaplets is to
- (a)
support the core
- (b)
compensate shrinkage
- (c)
provide binding
- (d)
None of the above
The purpose of gate is to
- (a)
feed the casting at a rate consistent with the rate of solidification
- (b)
feed the casting until all solidification takes place
- (c)
act as reservoir for molten metal
- (d)
None of the above
The purpose of sprue is to
- (a)
act as a reservoir for molten metal
- (b)
feed the casting until the solidification takes place
- (c)
feed molten from pouring basin to gate
- (d)
All of the above
The purpose of riser is to
- (a)
feed the casting at a rate consistent with the rate of solidification
- (b)
act as a reservoir for molten metal
- (c)
feed the casting until the solidification takes place
- (d)
None of the above
The ratio between the pattern shrinkage allowance of steel and cast iron is about
- (a)
2:1
- (b)
1:2
- (c)
1:1
- (d)
3:1
Investment casting uses pattern made of
- (a)
metal
- (b)
wood
- (c)
wax
- (d)
polymer