NHPC JE'21 ME: Daily Practices Quiz. 23-Sep-2021

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NHPC-JE’21 ME: Daily Practices Quiz

NHPC-JE’21 ME: Daily Practices Quiz 23-Sep-2021

Quiz: Mechanical Engineering
Exam: NHPC JE
Topic: Casting

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 6 Minutes

Q1. The use of chaplets in foundry practice are
(a) to align the mould boxes
(b) to ensure directional solidification
(c) to support the core
(d) to provide efficient venting

Q2. The casting process which is used for production of hollow pipes?
(a) Centrifugal casting
(b) Investment casting
(c) Sand casting
(d) Die casting

Q3. In casting, while designing Gating system, the formula of choke is (A) is
where, m = mass of casting, ρ = density of molten metal, H = effective metal height, ɳ = efficiency factor, t = pouring time
(a) A=m/(ρtɳ √2gH)
(b) A=mρt/(ɳ √2gH)
(c) A=2m/(ρtɳ √2gH)
(d) A=(mtɳ )/(ρ√2gH)
Q4. Which of the following is (are) the casting defect?
(a) Hot spot
(b) Blow holes
(c) Fusion
(d) All of these

Q5. What is the purpose of tuyeres in cupola furnace?
(a) To air blasting
(b) To collecting slag
(c) To collecting liquid metal
(d) To filling in the charge

Q6. Which of the following is not a part of gating system?
(a) Skim bob
(b) Splash core
(c) Ceramic filter
(d) All of these

Solutions

S1. Ans. (c)
Sol. The use of chaplets in foundry practice are to support the core inside the mould cavity overcome the metallostatic forces and take care of self-weight.

S2. Ans. (a)
Sol. The casting process which is used for production of making bigger size hollow symmetrical pipes is Centrifugal casting.
Centrifugal casting is the process in which the mould is rotated rapidly about its central axis as the molten metal is poured into it.

S3. Ans. (a)
Sol. Choke area (A)
A=m/(ρtɳ √2gH)
S4. Ans. (d)
Sol. Casting defects are blow holes, open blow, pin hole porosity, cuts and washes, metal penetration, fusion, runout, misrun and cold shut, slag inclusion hot tear and hot spot.

S5. Ans. (d)
The purpose of tuyeres in cupola furnace is to supply of air for combustion in cupola with the help of blower.

S6. Ans. (d)
All the listed components are the part of gating system.