This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Rocking Furnace”.
1. Which of the following material is not melted by an indirect electric arc furnace?
c) Cast iron
Explanation: An indirect electric arc furnace cannot be used for melting zinc, but for melting steel, cast iron or copper and its alloys, this method can be used.
2. What is the maximum capacity of a rocking furnace?
a) 0.5 ton
b) 1 ton
c) 2 tons
d) 3 tons
Explanation: An indirect arc furnace or a rocking furnace has its capacity ranging from a few kilograms to up to 2 tons. It is generally used for smaller melts.
3. Which of the following factors keeps the liquid metal level below the pouring sprout?
a) Angle of rocking furnace
b) Velocity of rocking furnace
c) Mounting distance
d) Temperature of the metal
Explanation: In the operation of indirect electric arc furnace, the liquid metal level has to be kept below the pouring sprout level. To accomplish this, the angle of rocking adjusts itself in different manners and maintains the liquid level.
4. How does the heat transfer take place in the rocking furnace?
d) Only radiation
Explanation: In a rocking furnace, the heat is first radiated from the hot refractory walls and the arc and conduction when the furnace starts rocking from the wall lining.
5. Which of the following is not valid for rocking furnace operation?
a) Causes overheating
b) Uniform composition of melt
c) Damage to the refractory lining
d) Fast melting
Explanation: In an indirect electric arc furnace, the rocking of furnace causes the melting to speed up, it also causes uniform composition of melt and does some damage to the refractory lining. This process does not cause overheating, instead it avoids it.
6. Which metal is charged before the actual operation in a rocking furnace begins?
a) Gray iron
c) Pig iron
Explanation: Inside the furnace, before beginning the actual process, the pig iron is charged. Above this charged pig iron, the scrap is then placed.
7. The electrodes used in the rocking furnace are typically made up of which material?
Explanation: In an indirect electric arc furnace, the electrodes are made up of graphite generally. When the scrap is placed, these electrodes are brought near for the current to jump.
8. Where does the diameter of the electrode, in rocking furnace become low?
a) Near cathode
b) Near anode
c) In the middle
d) Between cathode and the mid
Explanation: The graphite electrode is designed in such a way that its diameter gets reduced at the middle of the electrode. This reduction in diameter causes a high amount of resistance in the electrode, hence generating large amount of heat.
9. Low cost scrap metal can be used for rocking furnace.
Explanation: It is one of the advantages of the indirect electric arc furnace, that it does not essentially need a costly metal, but can operate even on low cost scrap metal.
10. The rocking furnace operation is expensive.
Explanation: The rocking furnace operation or the indirect electric arc furnace operates without making noise. There are electrodes needed for this operation and some amount of electricity, making it costly.
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