Category: Manufacturing Engineering Objective Questions

Manufacturing Processes Multiple Choice Questions on “Annealing – 1”.

1. The metal is said to be cold worked if it is plastically deformed at temperatures lower than _____
a) sublimation point
b) critical point
c) melting point
d) saturation point
Answer: c
Clarification: When a metal is plastically deformed at temperatures that are low relative to its melting point, it is said to be cold worked. A rough rule-of-thumb is to assume that plastic deformation corresponds to cold working if it is carried out at temperatures lower than one-half of the melting point measured on an absolute scale.

2. The fraction of total energy stored in the material _____ with increasing deformation.
a) increases
b) decreases
c) first increases and then decreases
d) remains constant
Answer: b
Clarification: Most of the energy expended in cold work appears in the form of heat, but a finite fraction is stored in the metal as strain energy associated with various lattice defects created by the deformation. The stored energy increases with increasing deformation, but at a decreasing rate, so that the fraction of the total energy stored decreases with increasing deformation.

3. The amount of stored energy can be greatly increased by _____
a) lowering the deformation temperature
b) increasing the deformation temperature
c) increasing the purity of the metal
d) reducing the net volume
Answer: a
Clarification: The amount of stored energy can be greatly increased by,
• increasing the severity of the deformation
• lowering the deformation temperature
• changing the pure metal to an alloy.

4. A soft annealed metal can have dislocation densities of the order of _____
a) 10⁵ to 10⁶ m^-2
b) 10⁸ to 10¹⁰ m^-2
c) 10¹⁰ to 10¹² m^-2
d) 10¹⁰ to 10¹⁵ m^-2
Answer: c
Clarification: Cold working is known to increase greatly the number of dislocations in a metal. A soft annealed metal can have dislocation densities of the order of 10¹⁰ to 10¹² m^-2, and heavily cold-worked metals can have approximately 10¹⁶.

5. Strain energy of the metal _____ with increasing the dislocation densities.
a) increases
b) decreases
c) does not change
d) first decreases and then remains constant
Answer: a
Clarification: Since each dislocation represents a crystal defect with an associated lattice strain, increasing the dislocation density increases the strain energy of the metal. Cold working is able to increase the number of dislocations in metal by a factor as large as 10⁴to 10⁶.

6. Vacancies in the metal lattice will be formed in greater numbers than interstitial atoms during _____
a) plastic deformation
b) brittle deformation
c) heating over melting temperature
d) non-linear deformation
Answer: a
Clarification: Since the strain energy associated with a vacancy is much smaller than that associated with an interstitial atom, it can be assumed that vacancies will be formed in greater numbers than interstitial atoms during plastic deformation.

7. Which of the following relations is true?
a) ΔG = ΔH – TΔS
b) ΔH = ΔG – TΔS
c) ΔT = ΔH – GΔS
d) ΔG = TΔH – ΔS
Answer: a
Clarification: ΔG = ΔH – T ΔS, this equation is known as Gibb’s free energy equation. While plastic deformation certainly increases the entropy of a metal, the effect is small compared to the increase in internal energy (the retained strain energy). The term T∆S in the free energy equation may be neglected and the free-energy increase equated directly to the stored energy. Where ∆G is the free energy associated with the cold work, ∆H is the enthalpy or stored strain energy, ∆S is the entropy increase due to the cold work, and T is the absolute temperature.

8. Free energy of cold-worked metals is _____ than/as that of annealed metals.
a) greater
b) lower
c) same
d) greater of few metals
Answer: a
Clarification: Since the free energy of cold-worked metals is greater than that of annealed metals, they may soften spontaneously. Heating a deformed metal greatly speeds up its return to the softened state.

9. The anisothermal anneal method, the energy release is determined as a function of temperature.
a) True
b) False
Answer: a
Clarification: The anisothermal anneal method, the cold worked metal is heated continuously from a lower to a higher temperature and the energy release is determined as a function of temperature. One form of the anisothermal anneal measures the difference in the power required to heat two similar specimens at the same rate.

10. The one specimen form above mentioned specimen is cold worked.
a) True
b) False
Answer: a
Clarification: One specimen of the two is cold worked before the heating cycle, while the other serves as a standard and is not deformed. During the heating cycle, the cold-worked specimen undergoes reactions that release heat and lower the power required to heat it in comparison with that required to heat the standard specimen. Measurements of the difference in power give direct evidence of the rate at which heat is released in the cold-worked specimen.

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Manufacturing Processes Multiple Choice Questions on “CNC Machining”.

1. In machining of a workpiece, the material is removed by_____
a) drilling action
b) melting action
c) shearing acting
d) using brittleness of the material
Answer: c
Clarification: There are different machining processes, such as turning, milling, boring etc. In all these cases metal is removed by a shearing process, which occurs due to the relative motion between the workpiece and the tool. Generally, one of the two rotates at designated and generally high speed, causing the shearing of material (known as chips), from the workpiece. The other moves relatively slowly to effect removal of metal throughout the workpiece.

2. The depth that the tool is plunged into the surface is called as ______
a) feed
b) depth of cut
c) depth of tool
d) working depth
Answer: b
Clarification: The depth of cut, DOC is the depth that the tool is plunged into the surface. Feed defines the relative lateral movement between the cutting tool and the workpiece. Thus, together with the depth of cut, feed decides the cross section of the material removed for every rotation of the job or the tool.

3. Feed is measured in units of _____
a) length/revolution
b) degree/revolution
c) length
d) velocity
Answer: a
Clarification: Feed is the amount of material removed for each revolution or per pass of the tool over the workpiece and is measured in units of length/revolution, length/pass or other appropriate units for the particular process.

4. CNC machining centres do not include operations like ______
a) milling
b) boring
c) welding
d) tapping
Answer: c
Clarification: CNC machining centres are developed for machining prismatic components combining operations like milling, drilling, boring and tapping. Gradually machines for manufacturing cylindrical components, called turning centres are also developed.

5. In CNC systems multiple microprocessors and programmable logic controllers work ______
a) in parallel
b) in series
c) one after the other
d) for 80% of the total machining time
Answer: a
Clarification: In CNC systems multiple microprocessors and programmable logic controllers work in parallel for simultaneous servo position and velocity control of several axes of a machine for contour cutting as well as monitoring of the cutting process and the machine tool.

6. Which of the following is not the advantage of CNC machines?
a) Higher flexibility
b) Improved quality
c) Reduced scrap rate
d) Improved strength of the components
Answer: d
Clarification: CNC machines offer the following advantages in manufacturing:
• Higher flexibility
• Increased productivity
• Improved quality
• Reduced scrap rate
• Reliable and Safe operation
• Smaller footprint.

7. In how many ways CNC machine tool systems can be classified?
a) 2
b) 3
c) 4
d) 5
Answer: b
Clarification: CNC machine tool systems can be classified in various ways such as:
• Point-to-point or contouring: depending on whether the machine cuts metal while the workpiece moves relative to the tool
• Incremental or absolute: depending on the type of coordinate system adopted to parameterise the motion commands
• Open-loop or closed-loop: depending on the control system adopted for axis motion control.

8. Point-to-point systems are used for _____
a) reaming
b) parting
c) grooving
d) facing
Answer: a
Clarification: Such systems are used, typically, to perform hole operations such as drilling, boring, reaming, tapping and punching. In a PTP system, the path of the cutting tool and its feed rate while traveling from one point to the next are not significant, since, the tool is not cutting while there is motion.

9. In part programming, interpolation is used for obtaining _______ trajectory.
a) helicoidal
b) pentagonal
c) triangular
d) zig-zag
Answer: a
Clarification: Interpolation consists of the calculation of the coordinated movement of several axes using the programmed parameters, in order to obtain a resulting trajectory, which can be of various types, such as:
– Straight line
– Circular
– Helicoidal.

10. For CNC machining skilled part programmers are needed.
a) True
b) False
Answer: a
Clarification: The main disadvantages of NC systems are:
• Relatively higher cost compared to manual versions
• More complicated maintenance due to the complex nature of the technologies
• Need for skilled part programmers.

11. An absolute NC system is one in which all position coordinates are referred to one fixed origin called the zero point.
a) True
b) False
Answer: a
Clarification: An absolute NC system is one in which all position coordinates are referred to one fixed origin called the zero point. The zero point may be defined at any suitable point within the limits of the machine tool table and can be redefined from time to time.

Manufacturing Engineering Multiple Choice Questions on “Introduction To Plastics”.

1. The polymerization of two or more chemically similar monomers forming a long molecular chain is termed as ____________
a) addition polymerization
b) copolymerization
c) condensation polymerization
d) step-growth polymerization
Answer: a
Clarification: Addition polymerization (also called as chain-growth polymerization) involves addition of two or more ‘similar’ monomers to form a long chain molecule. In, addition polymerization, empirical formula is the same as that of monomer. Polyolefins are formed through addition polymerization.

2. The polymerization of two or more chemically different monomers forming a long molecular chain is termed as ____________
a) addition polymerization
b) copolymerization
c) condensation polymerization
d) chain growth polymerization
Answer: b
Clarification: Copolymerization involves polymerization of two or more different monomers to form a long chain molecule. A well-known ‘Nylon 66’ is a copolymer of hexamethylenediamine and adipic acid.

3. The polymerization of two or more chemically different monomers forming a cross link polymer along with a by-product (can be either water or ammonia) is termed as ____________
a) addition polymerization
b) copolymerization
c) condensation polymerization
d) chain-growth polymerization
Answer: c
Clarification: Condensation polymerization (also called as step-growth polymerization) involves condensation (losing small molecules as by-products, usually such as water, methanol and ammonia) of different monomers to form a cross linked polymer. In, condensation polymerization, empirical formula is different as that of monomer. Polymers like polyamides, polyacetals and proteins are formed through condensation polymerization.

4. Which of the following additive is used as an initiator in polymerization reaction?
a) Benzoyl peroxide
b) Mica
c) Glass powder
d) Hydrogen peroxide
Answer: d
Clarification: Addition polymerization involves three steps for form an addition polymer, known as initiation, propagation and termination. In the initiation step, an initiator like hydrogen peroxide, easily split to form two species with a free electron attached to each.

5. Thermosetting plastics have ____________
a) 1-Degree bond
b) 2-Degree bond
c) 3-Degree bond
d) 0-Degree bond
Answer: a
Clarification: A thermosetting plastic is a polymer which gets irreversibly hardened when heated. They have a three-dimensional network of ‘1-degree’ primary bond. A well-known example of this kind are bakelite, polyester and epoxy resin, etc.

6. Which of the following is a primary bond network of thermosetting plastics?
a) 1-Dimensional
b) 3-Dimensional
c) 2-Dimensional
d) 0-Dimensional
Answer: b
Clarification: Thermosetting plastics have a three-dimensional network of ‘1-degree’ primary bond.

7. Thermoplastics have _____________
a) 1-Degree bond
b) 2-Degree bond
c) 3-Degree bond
d) 0-Degree bond
Answer: b
Clarification: A thermoplastic is a polymer which gets softened when heated. They have a one-dimensional network of ‘2-degree’ secondary bond. A well-known example of this kind are PET (polyethylene terephthalate), PVC (polyvinyl chloride), and PP (polypropylene) etc.

8. Which of the following is a secondary bond network of thermoplastics?
a) 1-Dimensional
b) 3-Dimensional
c) 2-Dimensional
d) 0-Dimensional
Answer: a
Clarification: Thermoplastics have a one-dimensional network of ‘2-degree’ secondary bond.

9. Thermoplastics become softer upon heating.
a) True
b) False
Answer: a
Clarification: Thermoplastics have 1-dimensional secondary bond structure, due to this, when heated, their individual polymer chains can slide one over other, thus making them softer.

10. Thermosetting plastics become softer upon heating.
a) True
b) False
Answer: b
Clarification: Thermosetting plastics have 2-dimensioanl primary bond structure (strong covalent cross links), thus making them stronger upon heating.

Manufacturing Engineering Multiple Choice Questions on “Cutting Fluids and Turning Process”.

1. In machining cast iron, no cutting fluid is required.
a) True
b) False
Answer: a
Clarification: None

2. The cutting fluid mostly used for machining alloy steels is :
a) water
b) soluble oil
c) dry
d) sulphurised mineral oil
Answer: d
Clarification: None

3. Cutting fluids are used to:
a) cool the tool
b) improve surface finish
c) cool the workpiece
d) all of the mentioned
Answer: d
Clarification: Functions of cutting fluids are
a) to cool the cutting tool and the workpiece
b) to lubricate the chip, tool and workpiece
c) to help carry away the chips
d) to lubricate some of the moving parts of the machine tool
e) to improve the surface finish
f) to prevent the formation of built up ridge
g) to protect the work against rusting

4. The cutting fluid mostly used for machining steel is:
a) water
b) soluble oil
c) dry
d) heavy oils
Answer: b
Clarification: Soluble oils are used for machining metals of high machinability.

5. Functions of cutting fluids are
a) to cool the cutting tool and the workpiece
b) to lubricate the chip, tool and workpiece
c) to help carry away the chips
d) all of the mentioned
Answer: d
Clarification: Functions of cutting fluids are
a) to cool the cutting tool and the workpiece
b) to lubricate the chip, tool and workpiece
c) to help carry away the chips
d) to lubricate some of the moving parts of the machine tool
e) to improve the surface finish
f) to prevent the formation of built up ridge
g) to protect the work against rusting

6. ______________ form mixtures ranging from emulsions to solutions.
a) Water miscible fluids
b) Neat oils
c) Synthetics
d) None of the mentioned
Answer: a
Clarification: Water miscible fluids form mixtures ranging from emulsions to solutions, which due to their high specific heat, high thermal conductivity, and high heat of vaporisation, are used on about 90% of all metal cutting and grinding operations.

7. Advantages of chemical fluids are
a) a very light residual film that is easy to remove
b) heat dissipation is rapid
c) good detergent properties
d) all of the mentioned
Answer: d
Clarification: Advantages of chemical fluids are
a) a very light residual film that is easy to remove
b) heat dissipation is rapid
c) good detergent properties
d) an easy concentration to control with no interference from tramp oils

8. The methods of application of cutting fluids are
a) flooding
b) jet application
c) mist application
d) all of the mentioned
Answer: d
Clarification: None.

9. In _____________ a high volume flow of the cutting fluid is generally applied on the back of the chip.
a) flooding
b) jet application
c) mist application
d) all of the mentioned
Answer: a
Clarification: In flooding, a high volume flow of the cutting fluid is generally applied on the back of the chip while in a jet application the cutting fluid, which may be either a liquid or a gas is applied in the form of a fine jet under pressure.

10. In _________ the cutting fluid, which may be either a liquid or a gas is applied in the form of a fine jet under pressure.
a) flooding
b) jet application
c) mist application
d) all of the mentioned
Answer: b
Clarification: In flooding, a high volume flow of the cutting fluid is generally applied on the back of the chip while in jet application the cutting fluid, which may be either a liquid or a gas is applied in the form of a fine jet under pressure.

11. ______________ controls both direction of chip flow and the strength of the tool tip.
a) Side rake angle
b) Relief angle
c) Rake angle
d) None of the mentioned
Answer: c
Clarification: Rake angle is important in controlling both the direction of chip flow and the strength of the tool tip.

12. _______________ acts downward on the tool tip.
a) Cutting force
b) Radial force
c) Thrust force
d) None of the mentioned
Answer: a
Clarification: The cutting force, F_C, acts downward on the tool tip and thus tends to deflect the tool downward and the workpiece upward. The cutting force supplies the energy required for the cutting operation.

13. _________ acts in the longitudinal direction.
a) Cutting force
b) Radial force
c) Thrust force
d) None of the mentioned
Answer: c
Clarification: The thrust force, F_t, acts in the longitudinal direction. It also is called the feed force, because it is in the feed direction of the tool.

14. ____________ acts in the radial direction.
a) Cutting force
b) Radial force
c) Thrust force
d) None of the mentioned
Answer: b
Clarification: The radial force, F_r, acts in the radial direction and tends to push the tool away from the workpiece.

15. For turning a small taper on a long workpiece, the suitable method is
a) by a form tool
b) by setting over the tail stock
c) by a taper turning attachment
d) none of the mentioned
Answer: b
Clarification: None

Manufacturing Engineering Multiple Choice Questions on “Ultrasonic Machining”.

1. Which of the following is an unconventional process of machining?
a) Milling
b) USM
c) Drilling
d) None of the mentioned
Answer: b
Clarification: USM stands for ultrasonic machining process and it is an unconventional process of machining.

2. Ultrasonic machining process can be used for
a) Conductors
b) Insulators
c) Metals
d) All of the mentioned
Answer: d
Clarification: Ultrasonic machining is more versatile and can be used for the metal as well as non metal.

3. Which of the following is a conventional process of machining?
a) Electro chemical machining
b) Electron beam machining
c) Ultrasonic machining
d) None of the mentioned
Answer: d
Clarification: All of the mentioned are unconventional process of machining.

4. For machining of plastic material which of the unconventional process can be used effectively?
a) Electro chemical machining
b) Electron beam machining
c) Ultrasonic machining
d) None of the mentioned
Answer: c
Clarification: Ultrasonic machining is more versatile and can be used for the metal as well as non metal.

5. Material removal rate in USM increases with
a) Decrease in volume of work material per impact
b) Increase in volume of work material per impact
c) Decrease in frequency
d) Decrease in number of particle making impact per cycle
Answer: b
Clarification: Material removal rate in USM is proportional to the volume of work material per impact.

6. Material removal rate in USM increases with
a) Decrease in volume of work material per impact
b) Decrease in volume of work material per impact
c) Decrease in frequency
d) Increase in number of particle making impact per cycle
Answer: d
Clarification: Material removal rate in USM is proportional to the number of particle making impact per cycle.

7. Material removal rate in USM increases with
a) Decrease in volume of work material per impact
b) Decrease in volume of work material per impact
c) Increases in frequency
d) Decreases in the number of particle making impact per cycle
Answer: c
Clarification: Material removal rate in Ultrasonic machining is proportional to frequency.

8. Element of machine which is used to convert high frequency electrical impulse into mechanical vibration in USM is known as
a) Tool
b) Feeding unit
c) Transducer
d) None of the mentioned
Answer: c
Clarification: Transducer is a device which is used to convert one form of energy to other.

9. Which of the following elements of USM is used to apply working force during machining operation?
a) Tool
b) Feeding unit
c) Transducer
d) None of the mentioned
Answer: b
Clarification: Feeding unit is used to apply working force during a machining operation.

10. Material removal rate in USM increases with
a) Decrease in amplitude
b) Decrease in grain size of abrasives
c) Decrease in frequency
d) Increase in amplitude
Answer: d
Clarification: Material removal rate in ultrasonic machining is proportional to amplitude.