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151.

Carbon picks up can be of what order?(a) 10%(b) 15%(c) 20%(d) 25%I had been asked this question in exam.My query is from Air Requirements and Metallurgical Control for Cupola in section Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Right option is (b) 15%

EASY explanation: In carbon pick up, there is an increase in the carbon content because of absorption from COKE, but there is a REDUCTION ALSO, because of oxidation. The order of carbon pick up can be of 15%.
Discussion
152.

Given: cupola diameter = 53cm, mass of bed charge = 465kg, height of groove = 7.2m. Find coke density.(a) 372.72 kg/m^3(b) 292.73 kg/m^3(c) 223.62 kg/m^3(d) 390.57 kg/m^3I have been asked this question during an interview.Question is taken from Coke Bed Charge Calculations topic in portion Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Correct option is (b) 292.73 kg/m^3

The best EXPLANATION: Here, d = 53cm = 0.53m, W = 465kg, HEIGHT of groove, H = 7.2m. Therefore, according to the formula, W = π/4 X d^2 x h x w => w= 465 / (π/4 x 0.53^2 x 7.2) => w = 292.73 kg/m^3.
Discussion
153.

What is the range of efficiency of cupola?(a) 20% to 40%(b) 30% to 50%(c) 40% to 60%(d) 50% to 70%I got this question in exam.Enquiry is from Zones and Efficiency of Cupola in chapter Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

The correct choice is (b) 30% to 50%

To ELABORATE: The EFFICIENCY of cupola is decided by factors LIKE heat USED in preheating, heat used in coke, heat used in oxidation and heat in the air blast. The efficiency of a cupola varies from 30% to 50%.
Discussion
154.

The volume of air passing in cupola is calculated using which device?(a) Area meter(b) Surface meter(c) Volume meter(d) Pressure meterI have been asked this question during an interview.Question is from Cupola topic in section Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Correct choice is (C) Volume METER

The explanation: The air flows in the CUPOLA, passing through the combustion ZONE. This volume of air can be calculated using a device called as Volume meter.
Discussion
155.

What is the amount of silica used in a slag?(a) 20% to 30%(b) 30% to 40%(c) 40% to 50%(d) 50% to 60%The question was asked during an interview.My question is based upon Zones and Efficiency of Cupola topic in portion Metal Furnace and Practice of Casting-Forming-Welding II

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Right choice is (c) 40% to 50%

To ELABORATE: Slag is KNOWN to be acidic in NATURE and it is found to have some amount of silica content in TERMS of percentage composition of about 40% to 50%.
Discussion
156.

What should the height of a cupola furnace?(a) 5m(b) 6m(c) 7m(d) 8mThe question was asked by my college professor while I was bunking the class.I'm obligated to ask this question of Cupola in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Right CHOICE is (B) 6m

Easiest explanation: The HEIGHT of a cupola furnace COMMONLY about 6m, WHEREAS the cupolettes have a height of approximately 2.5m to 4m. There is a spark arrester attached to the top of the cupola.
Discussion
157.

What is the amount of loss suffered by an induction heating furnace?(a) 1%(b) 2%(c) 3%(d) 4%This question was addressed to me in my homework.Enquiry is from Induction Furnace in chapter Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Correct choice is (a) 1%

Easy 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%.
Discussion
158.

What is the minimum frequency accepted for the motor, used in current production of high frequency induction furnace?(a) 430 cycles/second(b) 500 cycles/second(c) 550 cycles/second(d) 600 cycles/secondThe question was asked in my homework.Query is from Induction Furnace topic in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

The correct option is (b) 500 cycles/second

For explanation I WOULD say: In HIGH frequency induction furnace, motors which are equipped for the PRODUCTION of high frequency CURRENT can have a MINIMUM frequency of 500 cycles every second.
Discussion
159.

What would be the amount of current carried by the electrode for a direct arc furnace having capacity 50 tons?(a) 25 kilo amperes(b) 25 mega amperes(c) 25 micro amperes(d) 25 nano amperesI got this question by my college director while I was bunking the class.My query is from Direct Arc Furnace in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Correct answer is (a) 25 kilo amperes

Best EXPLANATION: For a direct arc furnace having a capacity of around 50 tons, the ELECTRODE would CARRY a current of approximately 25,000 amperes, which is 25 kA. These electrodes can be moved upwards and downwards.
Discussion
160.

What is typically the diameter of a direct arc furnace?(a) Up to 5m(b) Up to 6m(c) Up to 7m(d) Up to 8mThis question was addressed to me by my college professor while I was bunking the class.Asked question is from Direct Arc Furnace in portion Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

The correct answer is (b) Up to 6m

For EXPLANATION I would say: The direct ARC furnace is widely used in the STEEL FOUNDRIES for remelting steels of various compositions. In general, the DIAMETER of a direct arc furnace is found to be only up to 6 meters.
Discussion
161.

Heat loss through the sides of the crucible furnace does not affect the efficiency of the furnace.(a) True(b) FalseI got this question by my college professor while I was bunking the class.My query is from Crucible Furnaces topic in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Correct answer is (b) False

The best explanation: REDUCTION in heat loss through the sides of the crucible furnace can increase the efficiency of the furnace. It is generally estimated that the technology used like pre-fired RADIANT panels can IMPROVE the efficiency of crucible furnace by 30 % and also improves the melting rates of material used in the furnace.
Discussion
162.

Silicon carbide can be used as a liner for the crucible furnaces.(a) True(b) FalseThe question was asked during an interview for a job.This intriguing question originated from Crucible Furnaces topic in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Correct option is (a) True

To explain I would say: The LINERS USED in the crucible furnaces mainly are casted bricks which are mostly made by using the silicon carbide. Alumina CERAMIC can also be used as a liner, or SOMETIMES high temperature refractory materials like clay or cement are used as liners which are rammed on the crucible furnaces.
Discussion
163.

In the given figure of a side blown converter, what does the question mark represent?(a) Shell(b) Tuyeres(c) Wind box(d) Refractory liningThe question was asked in an interview for job.My question is taken from Converter in section Metal Furnace and Practice of Casting-Forming-Welding II

Answer» RIGHT choice is (d) REFRACTORY lining

To explain I would say: NONE.
Discussion
164.

In the given figure of a rotary melting furnace, what does the question mark depict?(a) Steel shell(b) Exhaust box(c) Refractory lining(d) Molten metalI had been asked this question during an online interview.I'm obligated to ask this question of Rotory Melting Furnace topic in chapter Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

The CORRECT answer is (a) Steel shell

To explain: The question MARK is depicting the steel shell, which is the OUTER body of the FURNACE.The shape of this furnace is TYPICALLY cylindrical.
Discussion
165.

In the following figure of the air furnace, what does the question mark represent?(a) Firing door(b) Firing place(c) Firing bridge(d) Firing barsI got this question in an interview for job.The doubt is from Reverberatory Furnace topic in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Right choice is (a) Firing door

Best explanation: The GIVEN FIGURE is that of an air FURNACE or a reverberatory furnace. The question mark in the picture is DEPICTING a firing door. Air and fuel are flown through this door only.
Discussion
166.

Height of the groove is inversely related to the diameter of the cupola.(a) True(b) FalseThe question was posed to me by my school principal while I was bunking the class.My enquiry is from Coke Bed Charge Calculations topic in chapter Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Correct ANSWER is (a) True

The EXPLANATION is: ACCORDING to the FORMULA, W = π/4 x d^2 x h x w, the height of the groove is inversely proportional to the diameter of the cupola, that is, with an INCREASE in the height there is a decrease in the diameter of the cupola.
Discussion
167.

Given: cupola diameter = 35cm, mass of bed charge = 300kg, coke density = 505kg/m^3. Find height of groove.(a) 6.1 m(b) 5.8 m(c) 3.6 m(d) 7.2 mI got this question in homework.This intriguing question comes from Coke Bed Charge Calculations topic in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

Right answer is (a) 6.1 m

Easy EXPLANATION: In this question, d = 35cm = 0.35m, w = 505 kg/m^3, W = 300kg. Therefore, ACCORDING to the formula, W = π/4 x d^2 x H x w, => h= 300 / (π/4 x 0.35^2 x 505) => h = 6.1m.
Discussion
168.

Which of the following is not considered under metal charge?(a) Steel scrap(b) Zinc scrap(c) Cast iron scrap(d) Pig ironThe question was asked in exam.This key question is from Zones and Efficiency of Cupola topic in section Metal Furnace and Practice of Casting-Forming-Welding II

Answer» CORRECT answer is (b) Zinc scrap

For explanation: AMONG the following, metal charge is found to consist of steel scrap, CAST iron scrap and PIG iron, but not zinc scrap.
Discussion
169.

Which of the following furnaces is mainly used for re-melting the steel metal?(a) Blast furnace(b) Electric arc furnace(c) Rotary furnace(d) Cupola furnaceThis question was posed to me in an online interview.Query is from Selection of Remelting Furnace in division Metal Furnace and Practice of Casting-Forming-Welding II

Answer»

The correct answer is (b) ELECTRIC arc furnace

Easy explanation: A furnace is a tool used for MELTING the ferrous and nonferrous materials for the production of castings; DIFFERENT furnaces are used for melting and re-melting the ferrous and nonferrous materials. A blast furnace basically used for melting the iron ORE to get pig iron, cupola furnace is used to produce cast iron metal and an electric arc furnace is used for re-melting the steel metal.
Discussion