Gray cast iron blocks 200 x 100 x 10 mm are to be cast

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Gray cast iron blocks 200 x 100 x 10 mm are to be cast in sand moulds, Shrinkage allowance for pattern making is 1%. The ratio of the volume of pattern to that of the casting will be

1. 0.97
2. 0.99
3. 1.61
4. 1.03

Correct Option: A

1% shrinkage allowance
⇒ 200 × 0.01 = 2mm
⇒ 100 × 0.01 = 1 mm
⇒ 10 × 0.01 = 0.1 mm
Gray cast iron expands after solidification.
Vp = pattern volume = (200 – 2) × (100 – 1)
Vc = Casting volume = (200 × 100 × 10)

V_p	=	(200 – 2) × (100 – 1) × 999
V_c		200 × 100 × 10

V_p	= 0.97
V_c