Respuesta :
Answer:
A) The value of the mold constant Cm in Chvorinov’s Rule is; Cm = 2.232 s/mm²
B) Time taken to solidify; Tts = 74.3 seconds
(A) Since a side is 50mm and all sides of a cube are equal, thus;
Volume of the cube is;
V = 50 x 50 x 50
V = 125,000 mm³
There are 6 faces of the cube, thus; Surface Area is;
A = 6 x (50 x 50)
A = 15,000 mm²
Thus;
Volume/Area is;
(V/A) = 125,000/15,000
(V/A) = 8.333 mm
Formula for mold constant Cm is given by the formula;
Cm = [Tts]/(V/A)²
where;
Tts is time taken to solidify and it's 155 seconds in the question. Thus;
Cm = 155/(8.333)²
Cm = 2.232 s/mm²
(B) We are told the Cylindrical casting has a diameter; D = 30 mm and Length; L = 50 mm.;
Volume of cylinder is;
V = (πD²L)/4
Thus;
V = (π × 30² × 50)/4 = 35,343mm³
Surface area of cylinder is;
A = (2πD²)/4 + (πDL)
Thus:
A = ((π x 30²)/2) + (π x 30 x 50)
A = 6126 mm²
Volume/Area is;
V/A = 35,343/6126 = 5.77
mm
Same alloy and mold type was used as in answer A above, thus, Cm is still 2.232 s/mm².
Since Cm = [Tts] /(V/A)²
Making Tts the subject, we have;
Tts = Cm x (V/A)²
Tts = 2.232 x (5.77)²
Tts = 74.3 seconds
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