Category: Manufacturing Engineering Objective Questions

250+ TOP MCQs on Grinding-1 and Answers

Manufacturing Engineering Multiple Choice Questions on “Grinding-1”.

1. Grinding wheel is specified as “A 46 K 5 B 17”. Grain size of a wheel will be
a) Coarse
b) Medium
c) Fine
d) Very Fine
Answer: b
Clarification: ’46’ represents grain size, which is medium grain size. Second value in the specification represents grain size.

2. Grinding wheel is specified as “C 8 K 5 B 17”. Grain size of a wheel will be
a) Coarse
b) Medium
c) Fine
d) Very Fine
Answer: a
Clarification: ‘8’ represents grain size, which is coarse. Second value in the specification represents grain size.

3. Grinding wheel is specified as “A 600 K 5 B 17”. Grain size of a wheel will be
a) Coarse
b) Medium
c) Fine
d) Very Fine
Answer: d
Clarification: ‘600’ represents grain size, which comes under very fine grain size. Second value in the specification represents grain size.

4. Which of the following grinding wheel will have fine grain size?
a) A 46 K 5 B 17
b) C 600 K 5 B 17
c) C 8 K 5 B 17
d) A 80 K 5 B 17
Answer: d
Clarification: Second place of ISO designation of the grinding wheel represents grain size and “80” comes under fine rain size.

5. Which of the following grinding wheel will have fine grain size?
a) A 46 K 5 B 17
b) C 600 K 5 B 17
c) C 8 K 5 B 17
d) A 80 K 5 B 17
Answer: c
Clarification: Second place of ISO designation of the grinding wheel represents grain size and “600” comes under very fine rain size.

6. Which of the following specified grinding wheel will have Aluminum oxide abrasive?
a) Z 46 K 5 B 17
b) C 600 K 5 B 17
c) C 8 K 5 B 17
d) A 80 K 5 B 17
Answer: d
Clarification: First place of ISO designation of the grinding wheel represents grain type and “A” represents aluminum oxide.

7. Which of the following specified grinding wheel will have Zirconia abrasive?
a) Z 46 K 5 B 17
b) C 600 K 5 B 17
c) C 8 K 5 B 17
d) A 80 K 5 B 17
Answer: a
Clarification: First place of ISO designation of the grinding wheel represents grain type and “Z” represents Zirconia.

8. Which of the following specified grinding wheel will have Silicon carbide abrasive?
a) Z 46 K 5 B 17
b) C 600 K 5 B 17
c) A 8 K 5 B 17
d) A 80 K 5 B 17
Answer: b
Clarification: First place of ISO designation of the grinding wheel represents grain type and “C” represents silicon carbide.

9. Operation done to make periphery of grinding wheel concentric with its axis to recover its lost shape is known as
a) Loading
b) Glazing
c) Dressing
d) Trueing
Answer: d
Clarification: Trueing is done to make periphery of grinding wheel concentric with its axis and to recover its lost shape.

10. Removing dull grains in order to make grinding wheel sharp is known as
a) Loading
b) Glazing
c) Dressing
d) Trueing
Answer: c
Clarification: Dressing is done to make grinding wheel shaft by removing dull grains at the top.

250+ TOP MCQs on Resistance Welding and Answers

Tough Manufacturing Engineering Questions on “Resistance Welding”.

1. Which one of the following is the simplest type of resistance welding used in making lap welds?
a) Resistance spot
b) Resistance seam
c) Projection
d) Upset

Answer: a
Clarification: The simplest form of the process is spot welding for lap welds, where the pressure is provided by clamping two or more overlapping sheets between two electrodes. Up to a thickness of 12.7 mm we can go for it.

2. The time required for electrodes to align and clamp the work piece together under them is known as?
a) Hold time
b) Off time
c) Squeeze time
d) Weld time

Answer: c
Clarification: Squeeze time is the time interval between the initial application of the electrode force on the work and first application of current. Squeeze time is necessary to delay the weld current until the electrode force has attained the desired level.

3. Time of current flow through the work piece till they are heated to require temperature is known as?
a) Hold time
b) Off time
c) Squeeze time
d) Weld time

Answer: d
Clarification: Weld time is the time during which welding current is applied to the metal sheets. The weld time is measured and adjusted in cycles in cycles of line voltage as are all timing functions.

4. Time, when pressure is maintained on the molten metal without electric current, is known as?
a) Hold time
b) Off time
c) Squeeze time
d) Weld time

Answer: a
Clarification: Hold time is the period programmed into the weld controller, typically between the end of weld time and the command to open the electrode.

5. The time after which the pressure is released, and metal piece is removed for next cycle is known as?
a) Hold time
b) Off time
c) Squeeze time
d) Weld time

Answer: b
Clarification: Off time is the time after which the pressure is released, and metal piece is removed for next cycle. It begins automatically after hold time.[/

6. The spot formed between the interface of work piece, when strong current and pressure is applied is known as?
a) Joint
b) Nugget
c) Core
d) Tee

Answer: b
Clarification: The spot formed between the interface of work piece when strong current and pressure is applied is known as a nugget. It may be of any shape.

7. In which of the following welding process disc electrodes are used instead of the cylindrical electrode?
a) Resistance spot
b) Resistance seam
c) Projection
d) Upset

Answer: b
Clarification: In resistance seam welding disc electrodes are used instead of the cylindrical electrode. Disc are rotated for the welding operation.

8. In which of the following operation embossing is required before welding?
a) Resistance spot
b) Resistance seam
c) Projection
d) Upset

Answer: c
Clarification: In projection, welding embossing is required before welding. It is non-productive time used in preparation of welding.

9. In which of the following welding operation the pieces are joined by butt joint?
a) Resistance spot
b) Resistance seam
c) Projection
d) Upset

Answer: d
Clarification: Upset welding or resistance butt welding is a welding technique that produces coalescence simultaneously over the entire area of abutting surfaces or progressively along a joint, by the heat obtained from resistance to electric current through the area where those surfaces are in contact.

10. In which of the following operation it is possible to weld more than one spot at a given time?
a) Resistance spot
b) Resistance seam
c) Projection
d) Upset

Answer: c
Clarification: The advantage of projection welding include flexibility, as the welder can weld more than one spot at a time. Additionally, the welder can position welded spots more closely to each other than is possible with spot welding.

250+ TOP MCQs on Metal Casting Processes Equipment and Answers

Manufacturing Engineering Multiple Choice Questions on “Metal Casting Processes and Equipment”.

1. Which of the following are typically made of sand, plaster, ceramics and similar materials and generally are mixed with various binders?
a) Permanent molds
b) Expendable molds
c) Composite molds
d) Ceramic molds
Answer: b
Clarification: Expendable molds, which typically are made of sand, plaster, ceramics, and similar materials and generally are mixed with various binders (bonding agents) for improved properties whereas permanent molds, which are made of metals that maintain their strength at high temperatures.

2. Which of the following are made of metals that maintain their strength at high temperatures?
a) Permanent molds
b) Expendable molds
c) Composite molds
d) Ceramic molds
Answer: a
Clarification: Expendable molds, which typically are made of sand, plaster, ceramics, and similar materials and generally are mixed with various binders (bonding agents) for improved properties whereas permanent molds, which are made of metals that maintain their strength at high temperatures.

3. Which of the following expandable molds are less heat conductors than metallic molds?
a) metallic
b) nonmetallic
c) composite
d) ceramic
Answer: b
Clarification: Metal molds are better heat conductors than expendable non-metallic molds, hence, the solidifying casting is subjected to a higher rate of cooling, which in turn affects the microstructure and grain size Within the casting.

4. Which of the following are made of two or more different materials (combining the advantages of each material)?
a) Permanent molds
b) Expendable molds
c) Composite molds
d) Ceramic molds
Answer: c
Clarification: Composite molds, which are made of two or more different materials (such as sand, graphite, and metal) combining the advantages of each material.

5. The directional solidification in casting can be improved by using __________
a) chaplets and riser
b) chills and padding
c) chaplets and padding
d) chills and riser
Answer: d
Clarification: Directional solidification is solidification that occurs from farthest end of the casting and works its way towards the sprue. Chills and riser are used in improving directional solidification.

6. In permanent mold casting method __________
a) molten metal is poured in a metallic mold, retained in the mold long enough for the outer skin to solidify and finally mold is turned over to remove molten metal still in molten condition
b) molten metal is poured and allowed to solidify while the mold is revolving
c) Molten metal is forced into mold under high pressure
d) none of the mentioned
Answer: d
Clarification: Permanent mold castings are used repeatedly and are designed in such a way that the casting can be removed easily and the mold used for the next casting. Metal molds are better heat conductors than expendable non-metallic molds hence, the solidifying casting is subjected to a higher rate of cooling, which in turn affects the microstructure and grain size Within the casting.

7. In which of the following casting method, the molten metal is poured and allowed to solidify while the mold is revolving?
a) die casting method
b) slush casting method
c) centrifugal casting method
d) investment casting method
Answer: c
Clarification: A casting process in which the molten metal is poured and allowed to solidify while the mold is revolving, is called centrifugal process. The casting produced under this centrifugal force is called centrifugal casting. This process is especially designed for a casting of symmetrical shape.

8. In a hot chamber die casting machine __________
a) melting pot is separate from the machine
b) melting pot is an integral part of the machine
c) melting pot may have any location
d) there is no melting pot in die casting machine
Answer: b
Clarification: In a hot chamber die casting machine, the melting pot is an integral part of the machine. The molten metal is forced in the die cavity at a pressure from 7 to 14 MPa.

9. Cast iron and steel pipes are produced by __________
a) slush casting
b) investment casting
c) true centrifugal casting
d) die casting
Answer: c
Clarification: The method of Cast Iron pipe production used universally today is to form pipes by spinning or centrifugal action. Compared with vertical casting in sand molds, the spun process results in faster production, longer pipes with vastly improved metal qualities, a smoother inner surface and reduced thickness and consequent light weight.

10. Which of the following statement is wrong?
a) The hot chamber die casting machine is used for casting zinc, tin, lead and other low melting alloys
b) The cold chamber die casting machine is used for casting aluminum, magnesium, copper base alloys and other high melting alloys
c) The castings produced by centrifugal casting method have open and coarse grained structure
d) The castings produced by centrifugal casting method have fine grained structure
Answer: c
Clarification: The casting produced by centrifugal casting process have dense and fine grained structure.

11. The melting temperature of non-ferrous alloys, to be casted in a cold chamber die casting machine are of?
a) low melting temperature
b) high melting temperature
c) two eutectic points
d) three eutectic points
Answer: b
Clarification: In a cold chamber die casting machine, the melting pot is usually separate from the machine and the molten metal is not transferred to injection mechanism by ladle. The pressure on the casting metal may vary from 21 to 210 MPa and in some cases may reach 700 MPa.

12. The centrifugal casting method, is used for casting articles of __________
a) symmetrical shape about horizontal axis
b) symmetrical shape about vertical axis
c) irregular shape
d) sphere shape
Answer: a
Clarification: In centrifugal casting, because gravity force is applied in same in horizontal direction axis, so the material is distributed equally in all directions.

250+ TOP MCQs on Fluid Flow and Heat Transfer and Answers

Manufacturing Engineering Multiple Choice Questions on “Fluid Flow and Heat Transfer”.

1. The flow of fluid which is highly chaotic is called as?
a) Laminar
b) Turbulence
c) Reynolds
d) Irrotational flow
Answer: b
Clarification: Turbulent flow is chaotic. However, not all chaotic flows are turbulent. Turbulent flow is characterized by the irregular movement of particles of the fluid. In contrast to laminar the fluid does not flow in parallel layers, the lateral mixing is very high, and there is a disruption between the layers. Turbulence is also characterized by recirculation, eddies, and apparent randomness, in other sense, in turbulent flow-the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction.

2. The capability of molten metal to fill mold cavities is called ____________
a) viscosity
b) fluidity
c) turbulence
d) velocity
Answer: b
Clarification: Fluidity is the property of a fluid which allows fluid to flow. In general understanding, one can say, the fluidity is inversely proportional to viscosity. Factors affecting fluidity in casting are as follows.
i. Modulus: fluidity length increases as the modulus (volume/surface area) of the casting increases
ii. Section thickness: larger thickness of section results in higher fluidity
iii. Heat transfer coefficient: a reduction in the rate of heat transfer will increase fluidity
iv. Superheating: the temperature increment above the melting point increases fluidity
v. Mould temperature: higher mould temperature increases fluidity
vi. Pouring rate: lower pouring rates decrease fluidity because of larger cooling.

3. The liquid metal reduces its fluidity mainly due to?
a) high viscosity
b) high friction factor
c) high surface tension
d) high turbulence
Answer: c
Clarification: A high surface tension of the liquid metal reduces fluidity. Because of this, oxide films on the surface of the molten metal have a significant adverse effect on fluidity.

4. The slower the rate of pouring molten metal into the mold, the nature of fluidity will be?
a) lower
b) higher
c) constant
d) either higher or lower
Answer: a
Clarification: The slower the rate of pouring molten metal into the mold, the lower is the fluidity because of the higher rate of cooling when poured slowly.

5. With an increase in the thickness of insulation around a circular pipe, heat loss to surrounding due to ____________
a) convection increase, while that the due to conduction decreases
b) convection decrease, while that due to conduction increases
c) convection and conduction decreases
d) convection and conduction increases
Answer: b
Clarification: By increasing the thickness of insulation, the convection heat transfer co-efficient decreases and heat loss by the convection also decreases. These both cases are limited for the critical thickness of insulation.

6. For a given heat flow and for the same thickness, the temperature drop across the material will be maximum for ____________
a) copper
b) steel
c) glass-wool
d) refractory brick
Answer: c
Clarification: Q = -kA (dT/dx)
Qdx/A = -kdT
therefore, kdT = constant or dT ∞ 1/k.

7. In descending order of magnitude, the thermal conductivity of:
i. Pure iron,
ii. Liquid water,
iii. Saturated water vapour, and
iv. Pure aluminium
can be arranged as?
a) (i), (ii), (iii) and (iv)
b) (ii), (iii), (i) and (iv)
c) (iv), (i), (ii) and (iii)
d) (iv), (iii), (ii) and (i)
Answer: c
Clarification: Thermal conductivity of values at room temperature are tabulated below:

S.No. Material Thermal Conductivity (W/m-K)
1 Iron 79.5
2 Water 0.6
3 Water vapour 0.025
4 Aluminium 150

8. A copper block and an air mass block having similar dimensions are subjected to symmetrical heat transfer from one face of each block. The other face of the block will be reaching the same temperature at a rate is?
a) Faster in air block
b) Faster in copper block
c) Equal in air as well as copper block
d) Cannot be predicted with the given information
Answer: b
Clarification: Copper has a thermal conductivity of 400 W/m-K and air has an value of 0.026 W/m-K.

9. Consider the following statements:
The Fourier heat conduction equation Q = -kA(dT/dx) presumes
i. Steady-state conditions
ii. Constant value of thermal conductivity.
iii. Uniform temperatures at the wall surfaces
iv. One-dimensional heat flow.
Which of the above statements are correct?
a) (i), (ii) and (iii) are correct
b) (i), (ii) and (iv) are correct
c) (ii), (iii) and (iv) are correct
d) (i), (iii) and (iv) are correct
Answer: d
Clarification: Thermal conductivity may constant or variable.

10. The outer surface of a long cylinder is maintained at constant temperature. The cylinder does not have any heat source. The temperature in the cylinder will?
a) Increase linearly with radius
b) Decrease linearly with radius
c) Be independent of radius
d) Vary logarithmically with radius
Answer: d
Clarification: In case of cylinder, in Q = -kA (dT/dr), thus indicating the logarithmic change.

11. For conduction through a spherical wall with constant thermal conductivity and with inner side temperature greater than outer wall temperature, (one dimensional heat transfer), what is the type of temperature distribution?
a) Linear
b) Parabolic
c) Hyperbolic
d) Logarithmic
Answer: c
Clarification: Temp distribution would be t – t1.

250+ TOP MCQs on Electrochemical Grinding and Answers

Manufacturing Processes Multiple Choice Questions on “Electrochemical Grinding”.

1. In electro-chemical grinding, grinding wheel is used as a cathode.
a) True
b) False
Answer: a
Clarification: ECG is similar to electro-chemical machining, only difference is the abrasive grinding wheel is used as a cathode instead of a tool shaped like the contour to be machined.

2. ECG is suitable for which of the following materials?
a) Tungsten carbide
b) Polymers
c) Iron
d) Nickel
Answer: a
Clarification: ECG is used primarily to machine difficult to cut alloys such as stainless steel, hastelloy, inconel, monel, waspally and tungsten carbide, heat treated workpieces, fragile or therm-sensitive parts, or parts for which stress-free and burr free results are required.

3. In ECG, grinding action removes ____________
a) workpiece material from the surface
b) corroded surface layer making workpiece ready for electro-chemical process
c) oxide film formed on the surface
d) particles removed from surface after chemical action
Answer: c
Clarification: ECG removes metal by combination of electro-chemical and grinding actions. The grinding action removes the buildup of oxide film on the surface of the workpiece.

4. As compared to electrochemical machining (ECM), ECG consumes less power.
a) True
b) False
Answer: a
Clarification: Power required for ECG is less than for ECM since the machining area is smaller and the abrasive grinding wheel removes the oxide film, thus preventing the excess use of chemical/electrolyte.

5. Nozzles are used to _____________
a) spray coolant on the wheel
b) ensure proper wetting of the wheel
c) spray chemical directly on the work piece
d) nozzles are not used in ECG
Answer: b
Clarification: Nozzles are used to ensure proper wetting action of the wheel. Nozzle creates a partial vacuum and causes the electrolyte to be sucked up, filling the cavities around the grit. The rotation of the wheel carries the electrolyte into the area of contact.

6. In ECG, rate of formation of oxide film is faster than that in ECM.
a) True
b) False
Answer: a
Clarification: The electrolyte used in ECG is designed to enable faster formation of oxide films on the workpiece, whereas in ECM, the oxide film must dissolve at once in the electrolyte.

7. Electrolyte in ECG should provide _____________
a) lower chemical activity
b) allowance to stray currents
c) high stock removal efficiency
d) higher corrosion tendency
Answer: c
Clarification: Desirable electrolyte should provide: high conductivity, high stock removal efficiency, passivation to limit stray currents, good surface finishes and corrosion inhibition.

8. Which of the following is true for ECG?
a) Higher the grinding wheel rpm, higher is the MRR
b) Higher the current density, faster the removal rate
c) Stronger the electrolyte, poor surface finish
d) Higher the hardness of the workpiece, lower the current density required
Answer: b
Clarification: The removal rate for ECG is governed by the current density, just as in ECM: as with ECM, the higher the current density, the faster the removal rate and better the resulting surface finish.

9. Feed rates in ECG vary with a grinding method.
a) True
b) False
Answer: a
Clarification: In ECG. Feed rates vary with different parameters, depending on the grinding method: if the feed rate is running too slowly for the application, a large overcut will be produced that will result in poor surface finishes and tolerances and if the feed rate is too fast, the abrasive particles will be prematurely forced in too the workpiece, resulting in excessive wheel wear.

10. Which of the following is true about ECG?
a) Lower MRRs when grinding hard, heat sensitive materials
b) Machining of soft metals like aluminium can be easily done
c) Difficult to machine materials with high hardness like tungsten carbide
d) Burr-free sharpening of needles
Answer: d
Clarification: Applications of ECG are as follows;
(1) Single largest use for ECG is in the manufacturing and remanufacturing of turbine blades and vanes for aircraft turbine engines
(2) Grinding of tungsten carbide tool inserts
(3) Re-profiling worn locomotive traction motor gears
(4) Burr-free sharpening of hypodermic needles
(5) Grinding of surgical needles, other thin wall tubes, and fragile parts
(6) Machining of fragile or very hard and tough material – honey comb, thin walled tubes and skins
(7) High MRR’s when grinding hard, tough, stringy, work-hardenable or heat sensitive materials.

250+ TOP MCQs on Electrochemical Etching – 12 and Answers

Manufacturing Processes Multiple Choice Questions on “Electrochemical Etching – 12”.

1. Metal-assisted chemical etching approach is widely used to produce pSi structures with precisely defined geometric features.
a) True
b) False
Answer: a
Clarification: Metal-assisted chemical etching of silicon is considered a simple and cost-competitive alternative to conventional electrochemical methods. This approach has been used to produce pSi structures with precisely defined geometric features and characteristics not achievable by other fabrication approaches.

2. _____ can be controlled in metal-assisted etching.
a) Etching rate
b) Etching direction
c) Etching area
d) Etching temperature
Answer: b
Clarification: The etching direction in metal-assisted etching can be controlled on silicon (100) and non-(100) directions to produce pSi structures with slanted growth directions. 100, 110, 111, etc. are miller indices for the orientation of the Si structure.

3. Metal-assisted etching can produce pSi structures with high surface-to-volume ratio.
a) True
b) False
Answer: a
Clarification: Metal-assisted etching enables the fabrication of pSi structures with high surface-to-volume ratio, high crystalline quality and low level of defects.

4. It can be said that metal-assisted etching of silicon is an alternative approach to conventional electrochemical etching methods.
a) True
b) False
Answer: a
Clarification: Metal-assisted etching can produce pSi structures with high surface-to-volume ratio high crystalline quality and low level of defects. In addition, metal-assisted etching makes it possible to produce pSi structures within a broad range of feature sizes, which can range from 5 nm to > 1 μm. For these reasons, metal-assisted etching of silicon has become an alternative approach to conventional electrochemical etching methods.

5. Etching rate is affected by _____
a) temperature
b) pressure
c) coating on Si surface
d) material thickness
Answer: c
Clarification: When a silicon substrate is partly covered by a noble metal and it is immersed in an etchant solution composed of an oxidative agent (e.g. hydrogen peroxide) and HF, the silicon beneath the noble metal is etched at a faster rate than that of the uncovered silicon.

6. Geometric features of the pSi structure are determined by noble metal mask.
a) True
b) False
Answer: a
Clarification: Basically, the geometric features of the resulting pSi structures are established by the noble metal mask. The noble metal sinks into the silicon substrate, producing pores or pillars depending on the etching conditions and the metal features.

7. In metal-assisted etching of pSi, chemical reactions occur between _____
a) noble metal and etching agent
b) silicon and etching agent
c) noble metal and silicon
d) no such reactions occur in metal-assisted etching
Answer: c
Clarification: As far as the mechanisms and reactions involved in the formation of pSi structures produced by metal-assisted etching is concerned, it is well-known that chemical and electrochemical reactions occur near the interface between the noble metal and the silicon substrate when the system is immersed in an etchant composed of HF and H2O2.

8. In metal-assisted etching of pSi, the noble metal works as a cathode.
a) True
b) False
Answer: a
Clarification: In this system, the noble metal works as a cathode, where hydrogen peroxide is reduced at the metal surface following these electrochemical reactions while the silicon works as the anode:
H2O2 + 2H+ -> 2H2O + 2H+
2H+ -> H2 + 2 protons.

9. In the above mentioned method, charge transfer between noble metal and silicon occurs for the oxidation.
a) True
b) False
Answer: a
Clarification: In analogy with chemical etching of silicon, it is accepted that charge transfer between noble metal and silicon occurs for the oxidation and dissolution of the latter by hole injection mechanism.

10. In hole injection mechanism, holes are created in the noble metal.
a) True
b) False
Answer: a
Clarification: In that system, the noble metal plays the role of cathode, where the reduction of the oxidant takes place. Holes generated in the noble metal are then injected into the silicon substrate, oxidising silicon atoms, which subsequently are dissolved by reacting with HF.