Manufacturing Engineering objective Questions with Answers - Set 05

Practice Test: Question Set - 05

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1. The hardness of a grinding wheel is determined by the

(A) Hardness of abrasive grains

(B) Ability of the bond to retain abrasives

(C) Hardness of the bond

(D) Ability of the grinding wheel to penetrate the work piece

Answer: Option B
Explanation: Because each abrasive grain usually removes only a very small amount of material at a time, high rates of material removal can be achieved only if a large number of these grains act together. This is done by using bonded abrasives, typically in the form of a grinding wheel. The abrasive grains are held together by a bonding material which acts as supporting posts or brace between the grains and also increases the hardness of the grinding wheel.

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2. The cutting force in punching and blanking operations mainly depends on

(A) The modulus of elasticity of metal

(B) The shear strength of metal

(C) The bulk modulus of metal

(D) The yield strength of metal

Answer: Option B
Explanation: The blanking force is given by the relation,
Fb = τ × d × t
Where, τ = shear strength of material.

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3. In ECM, the material removal is due to

(A) Corrosion

(B) Erosion

(C) Fusion

(D) Ion displacement

Answer: Option D
Explanation: In ECM, the principal of electrolysis is used to remove metal from the work-piece. The material removal is due to ion displacement. The principal of electrolysis is based on Faraday’s law of electrolysis.

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4. Allowance in limits and fits refers to

(A) Maximum clearance between shaft and hole

(B) Minimum clearance between shaft and hole

(C) Difference between maximum and minimum sizes of hole

(D) Difference between maximum and minimum sizes of shaft

Answer: Option A
Explanation: Allowance is an intentional difference between the maximum material limits of mating parts. For shaft, the maximum material limit will be its high limit and for hole, it will be its low limit. So, allowance refers to maximum clearance between shaft and hole.

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5. Green sand mould indicates that

(A) Polymeric mould has been cured

(B) Mould has been totally dried

(C) Mould is green in colour

(D) Mould contains moisture

Answer: Option D
Explanation: A green sand mould is composed of a mixture of sand (silica sand, SiO₂), clay (which acts as binder) and water. The word green is associated with the condition of wetness or freshness and because the mould is left in the damp condition, hence the name “green sand mould”.

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6. In a gating system, the ratio 1: 2: 4 represents

(A) Sprue base area: runner area: ingate area

(B) Pouring basin area: ingate area: runner area

(C) Sprue base area: ingate area: casting area

(D) Runner area: ingate area: casting area

Answer: Option A
Explanation: Gate Ratio is defined as the ratio of sprue base area, followed by the total runner area and the total ingate area. The sprue base area is taken is unity.
So, 1: 2: 4 = Sprue base area: Runner area: Total ingate area

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7. Two streams of liquid metal which are not hot enough to fuse properly result into a casting defect known as

(A) Cold shut

(B) Swell

(C) Sand wash

(D) Scab

Answer: Option A
Explanation: Two streams of liquid metal which are not hot enough to fuse properly result into a casting defect known as cold shut. This defect is same as in sand mould casting. The reasons are:-
(i) Cooling of die or loss of plasticity of the metal.
(ii) Shot speed less.
(iii) Air-vent or overflow is closed.

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8. Which of the following engineering materials is the most suitable candidate for hot chamber die casting?

(A) Low carbon steel

(B) Titanium

(C) Copper

(D) Tin

Answer: Option D
Explanation: The hot chamber die casting process is used for low melting temperature alloys. Tin is a low melting temperature alloy.

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9. Volume of a cube of side ‘l’ and volume of a sphere of radius ‘r’ are equal. Both the cube and the sphere are solid and of same material. They are being cast. The ratio of the solidification time of the cube to the same of the sphere is

(A) (4π/6)³ × (r/l)⁶

(B) (4π/6) × (r/l)²

(C) (4π/6)² × (r/l)³

(D) (4π/6)² × (r/l)⁴

Answer: Option D
Solution:
According to Canine’s relation
Solidification time, (T) = q × (V/A)²
Where: V = Volume, A= Surface area, Q= Flow rate
q = constant of proportionality depends upon composition of cast metal
Using the subscript ‘c’ for the cube and subscript‘s’ for the sphere.
Given: Vc = Vs So, T ∝ 1/A²
So, Tc/Ts = (As/Ac)² = (4πr²/6l²)² = (4π/6)² × (r/l)⁴

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10. An expendable pattern is used in

(A) Slush casting

(B) Squeeze casting

(C) Centrifugal casting

(D) Investment casting

Answer: Option D
Explanation: Investment casting uses an expandable pattern, which is made of wax or of a plastic by moulding or rapid prototyping techniques. This pattern is made by injecting molten wax or plastic into a metal die in the shape of the pattern.

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11. Match the items of List-I (Equipment) with the items of List-II (Process) and select the correct answer using the given codes.

List-I (Equipment)	List-II (Process)
P. Hot Chamber Machine	1. Cleaning
Q. Muller	2. Core making
R. Dielectric Baker	3. Die casting
S. Sand Blaster	4. Annealing
	5. Sand mixing

(A) P-2, Q-1, R-4, S-5

(B) P-4, Q-2, R-3, S-5

(C) P-4, Q-5, R-1, S-2

(D) P-3, Q-5, R-2, S-1

Answer: Option D
Explanation: The correct pairs are, P-3, Q-5, R-2, S-1

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12. Misrun is a casting defect which occurs due to

(A) Very high pouring temperature of the metal

(B) Insufficient fluidity of the molten metal

(C) Absorption of gases by the liquid metal

(D) Improper alignment of the mould flasks

Answer: Option B
Explanation: Two streams of liquid metal which are not hot enough to fuse properly result into a casting defect, known as Misrun/cold shut. It occurs due to insufficient fluidity of the molten metal.

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13. Hardness of green sand mould increases with

(A) Increase in moisture content beyond 6 percent

(B) Increase in permeability

(C) Decrease in permeability

(D) Increase in both moisture content and permeability

Answer: Option C
Explanation: Permeability or porosity of the moulding sand is the measure of its ability to permit air to flow through it. So, hardness of green sand mould increases by restricted the air permitted in the sand i.e. decrease its permeability.

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14. The primary purpose of a sprue in a casting mould is to

(A) Feed the casting at a rate consistent with the rate of solidification

(B) Act as a reservoir for molten metal

(C) Feed molten metal from the pouring basin to the gate

(D) Help feed the casting until all solidification takes place

Answer: Option C
Explanation: From the pouring basin, the molten metal is transported down into the mould cavity by means of the sprue or down-gate. It is a vertical channel that connects the pouring basin with runners and gates.

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15. Shrinkage allowance on pattern is provided to compensate for shrinkage when

(A) The temperature of liquid metal drops from pouring to freezing temperature

(B) The metal changes from liquid to solid state at freezing temperature

(C) The temperature of solid phase drops from freezing to room temperature

(D) The temperature of metal drops from pouring to room temperature

Answer: Option C
Explanation: Since metal shrinks on solidification and contracts further on cooling to room temperature, linear dimensions of patterns are increased in respect of those of the finished casting to be obtained. This is called the “shrinkage allowance”. So, the temperature of solid phase drops from freezing to room temperature.

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View All Answers

(1) Answer: Option B
(2) Answer: Option B
(3) Answer: Option D
(4) Answer: Option A
(5) Answer: Option D
(6) Answer: Option A
(7) Answer: Option A
(8) Answer: Option D
(9) Answer: Option D
(10) Answer: Option D
(11) Answer: Option D
(12) Answer: Option B
(13) Answer: Option C
(14) Answer: Option C
(15) Answer: Option C

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