This set of Metal Casting Multiple Choice Questions & Answers (MCQs) focuses on “Low Frequency”.
1. A low frequency induction furnace works on what frequency current?
a) 40 cycles/second
b) 50 cycles/second
c) 60 cycles/second
d) 70 cycles/second
View Answer
Explanation: A low frequency induction furnace works on an alternating current supply. This alternating current possess a frequency of 60 cycles every second.
2. Which of the following can be controlled by a core type furnace for any material?
a) Pressure
b) Volume
c) Temperature
d) Rate of production
View Answer
Explanation: Any core type furnace can be used as a holding furnace for die casting as well as for permanent mold, as these furnaces are able to control the temperature of the metal.
3. What is the thermal efficiency of a low frequency induction furnace?
a) 60%
b) 70%
c) 80%
d) 90%
View Answer
Explanation: Any core type induction surface has a high amount of thermal efficiency. A low frequency induction furnace has a thermal efficiency of 80%.
4. What is the maximum capacity of a low frequency induction furnace in general?
a) 4 tons
b) 5 tons
c) 6 tons
d) 7 tons
View Answer
Explanation: The maximum capacity observed normally in a low frequency induction furnace is about 5 tons, which means, the furnace is able to operating on metals and alloys up to the mass of 5 tons.
5. What is the maximum power which can be provided for a low frequency induction furnace?
a) 350 kW
b) 400 kW
c) 450 kW
d) 500 kW
View Answer
Explanation: The maximum power which can be provided to a low frequency induction furnace is about 500000 watts, which is 50 kW. The minimum power which can be provided to it is approximately 60W.
6. What is the rate of melting of a low frequency induction furnace per kW rating?
a) 2 – 3 kg/hr
b) 2 – 3.5 kg/hr
c) 3 – 4 kg/hr
d) 3 – 4.5 kg/hr
View Answer
Explanation: The rate of melting of a low frequency induction furnace is around 2 to 3.5 kg per hour per kilo watt rating of the furnace.
7. A low frequency induction furnace works only on a primary coil.
a) True
b) False
View Answer
Explanation: A primary coil is employed in the working of a low frequency induction furnace. The coil is wound on laminated steel core and the secondary coil has one turn which is a channel or a loop.
8. What is the amount of loss suffered by an induction heating furnace?
a) 1%
b) 2%
c) 3%
d) 4%
View Answer
Explanation: In the melting of steel, there are losses suffered in the operation. In an induction heating furnace, the losses suffered are only about 1%.
9. Cast iron castings cannot be produced by melting which of the following materials?
a) Pig iron
b) Steel scrap
c) Iron
d) Copper
View Answer
Explanation: Cast iron castings can be produced by melting of pig iron, steel scrap, foundry returns such as risers or gates and iron contained alloys, but not copper.
10. Low frequency induction furnace are used for the production of malleable cast irons.
a) True
b) False
View Answer
Explanation: Any core type furnace is primarily used for remelting of non-ferrous metals and their respective alloys. But a low frequency induction furnace may be used if malleable cast irons are to be produced.
Sanfoundry Global Education & Learning Series – Metal Casting, Forming and Welding.
Practice 1000+ Multiple Choice Questions and Answers on Metal Casting and Metal Forming and Welding.
