Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) on “Furnaces for Melting”.
1. For melting of cast iron, which of the following furnace is used?
a) Rotary furnace
b) Cupola furnace
c) Pit furnace
d) Electric furnace
Answer: b
Clarification: Cupola is a heavy furnace and has the capability to melt down heavy metals like cast iron. Hence, the Cupola furnace is mostly used to melt cast iron for casting purposes.
2. Why is sand bed prepared for melting of metal in Cupola furnace?
a) It provides a refractory bottom
b) It soaks the moisture from the metal
c) It conducts the heat faster and uniformly
d) None of the mentioned
Answer: a
Clarification: A sand bed needs to be prepared because it provides a necessary refractory bottom for molten metal and coke.
3. What is the function of slag hole in a cupola furnace?
a) To tap the slag generated
b) To generate the slag
c) To allow outflow of gases
d) All of the mentioned
Answer: a
Clarification: Slag hole is a tapping hole in a cupola furnace. Through which slag generated during the melting process is tapped.
4. Incoming air pressure and quantity in cupola furnace are controlled by which of the following element?
a) Tuyeres
b) Tapping spout
c) Wind box
d) Blast pipe
Answer: c
Clarification: The air enters the cupola through the tuyers. But the air blowers in the wind box controls the requisite pressure and quantity of air coming inside.
5. Which of the following chemical compound, is the most common flux added to the charge in a cupola furnace?
a) Coke
b) Methane
c) Carbon dioxide
d) Limestone
Answer: d
Clarification: Limestone (CaCO3) is used as Flux in cupola furnace in a proportion of about 2-4% of the metal charge.
6. Which of the following metal has a melting point of about 1537oC and latent heat of fusion 65.0 cal/g?
a) Nickel
b) Copper
c) Zinc
d) Iron
Answer: d
Clarification: Iron is the metal having a melting point of about 1537oC and latent heat of fusion of 65.0 cal/g. It has a mean specific heat of 0.141 cal/g-oC and heat required for melting 1 Kg of iron is 1168 kJ.
7. Electric arc furnaces are most suitable for which of the following type of material?
a) Ferrous
b) Non-Ferrous
c) Both ferrous and nonferrous
d) Neither ferrous nor nonferrous
Answer: a
Clarification: Electric furnaces are more suitable for ferrous material in a larger capacity.
8. There is no direct contact of flame and metal in which of the following type of furnace?
a) Cupola
b) Crucible
c) Electric arc
d) Induction
Answer: b
Clarification: In Crucible furnace, metal is placed in a crucible of refractory material. The crucible is heated with electric resistance.
9. What is hearth in a furnace?
a) The electrodes are often called hearth
b) The walls of the furnace
c) The bowl shaped bottom of the furnace
d) The dome shaped roof of the furnace
Answer: c
Clarification: The hearth is that bowl shaped bottom of the furnace. It is made up of a high refractory material (bricked and granular).
10. Why are flux added to the charge ( parent metal to be melted) during melting of a metal?
a) To increase carbon content
b) To increase refractoriness
c) To add specific oxides
d) To remove specific oxides