Materials Science and Manufacturing Engineering Miscellaneous Difficult Questions and Answers

Materials Science and Manufacturing Engineering Miscellaneous

Solidification time of a metallic alloy casting is

α =	K	, α → Thermal Diffusivity
	ρC_P

as ↑ t (Solodification time)↓

Correct Option: D

α =	K	, α → Thermal Diffusivity
	ρC_P

as ↑ t (Solodification time)↓

In sand casting of hollow part of lead, a cylindrical core of diameter 120 mm and height 180 mm is placed inside the mould cavity. The densities of core material and lead are 1600 kg/m³ and 11300 kg/m³ respectively. The net force (in N) that tends to lift the core during pouring of molten metal will be

Net Buoyancy force, F
F = (11300 - 1600) × 9.81 × π/1 × (120)² × 180 × 10^-3
= 193.71 N

Correct Option: C

Net Buoyancy force, F
F = (11300 - 1600) × 9.81 × π/1 × (120)² × 180 × 10^-3
= 193.71 N

The mould filling time is seconds is

Mould filling time =	Volume
	Flow rate

=	100 × 100 × 100
	1.739 × 10⁵

= 5.75 sec

Correct Option: B

Mould filling time =	Volume
	Flow rate

=	100 × 100 × 100
	1.739 × 10⁵

= 5.75 sec

A cast Steel slab of dimension 30 × 20 × 5 cm is poured horizontally using a side riser. The riser is cylindrical in shape with diameter and height, both equal to D. The freezing ratio of the mould is

Correct Option: A

The shape factor for a casting in the form of an annular cylinder of outside diameter 30 cm, inside diameter 20 cm and height 30 cm (correction factor k = 1.0) will be

Shape factor =	L + W
	Thickness

W = πD_mean = π		30 + 20
		2

= 78.53 cm

t =	30 - 20	= 5 cm.
	2

Shape factor =	30 + 78.53	= 21.72
	5

Correct Option: A

Shape factor =	L + W
	Thickness

W = πD_mean = π		30 + 20
		2

= 78.53 cm

t =	30 - 20	= 5 cm.
	2

Shape factor =	30 + 78.53	= 21.72
	5