8/28/2011
GATE‐2003
IES‐2006
With a solidification factor of 0.97 x 106 s/m2, the solidification time (in seconds) for a spherical casting of 200 mm diameter is
According
(a) 539
(b) v
(b) 1078
(c) 4311
to
Chvorinov's
equation,
the
solidification time of a casting is proportional to: (a) v2
(d) 3233
(c) 1/v
[Ans. (b)]
(d) 1/v2 Where, v = volume of casting Compiled by: S K Mondal Made Easy
[Ans. (a)]
Compiled by: S K Mondal Made Easy
GATE‐2007 Volume of a cube of side 'l' and volume of a sphere of radius ‘r’ are equal. Both the cube and the sphere are solid and of same material. They are being cast. The ratio ti off the th solidification lidifi ti time ti off the th cube b to t the th same of the sphere is: (a )
3
⎛ 4π ⎞ ⎛ r ⎞ ⎜ 6 ⎟ ⎜l⎟ ⎝ ⎠ ⎝ ⎠
6
4π ⎞ ⎛ r ⎞ ⎟⎜ ⎟ ⎝ 6 ⎠⎝ l ⎠
( b ) ⎛⎜
2
2
4π ⎞ ⎛ r ⎞ ⎟ ⎜ ⎟ ⎝ 6 ⎠ ⎝l⎠
( c ) ⎛⎜
3
2
4π ⎞ ⎛ r ⎞ ⎟ ⎜ ⎟ ⎝ 6 ⎠ ⎝l⎠
( d ) ⎛⎜
4
Ans. (d) Compiled by: S K Mondal Made Easy
Compiled by: S K Mondal Made Easy
Modulus Method
Conventional Question ESE 2003:
y It has been empirically established that if the modulus
Compare the solidification time of two optimum side – risers of the same volume with one has cylindrical shape and other is i h h li d i l h d h i parallopiped. [30 Marks]
of the riser exceeds the modulus of the casting by a factor of 1.2, the feeding during solidification would be satisfactory. MR = 1.2 Mc y Modulus = volume/Surface area y In steel castings, it is generally preferable to choose a
riser with a height‐to‐diameter ratio of 1. Compiled by: S K Mondal Made Easy
Compiled by: S K Mondal Made Easy
Contd…
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