Question 91-100

Mechanical engineering interview questions with answers which are asked by HR and in technical rounds.

91)   What is magnetostriction effect?
Ans) When a rod of ferromagnetic material such as iron or nickel is kept in a magnetic field parallel to
its length, the rod suffers a change in its length. This phenomenon is known as magnetostriction
effect.

92)   What is piezoelectric effect?
Ans) When mechanical force is applied to one pair of opposite faces of certain crystal like quartz,
tourmaline, etc equal and opposite electric charges appear across its other faces.

93)   What is inverse piezoelectric effect?
Ans) When an a.c. voltage is applied across the piezoelectric crystal, it starts vibrating at the
frequency of the applied voltage. Ultrasonic wave generation is based on inverse piezoelectric
effect.

94)   What is feed mechanism ?
Ans) Feed system is used to apply the static load between the tool and the workpiece during
ultrasonic machining operation.

95)   What are the types of feed mechanism?
Ans) Gravity feed mechanism
        Spring loaded feed mechanism
        Pneumatic or hydraulic feed mechanism.

96)   State tool wear ratio.
Ans) It is defined as the ratio of volume of material removed from the work to volume of material
eroded from tool.

97)   What is the effect of abrasive grain size on machining rate in USM?
Ans) Material removal rate and surface finish are greatly influenced by grit or grain size of the
abrasive. For roughing work operation, grit size of 200-400 are used and for finishing operation
800-1000 are used.

98)   What are the types of work materials used for USM?
Ans) Hard and brittle metals like tungsten carbide, boron carbide, tool sterl, germanium, etc are used.
        Non metal like glass and ceramics are also used.

99)   What are the abrasive used in USM process?
Ans) Boron carbide, silicon carbide, aluminum oxide and diamond.

100) What is abrasive slurry?
Ans) It is a mixture of abrasive grain and water of definite proportion. (20-30%).

((More questions are on the way...))

Question 81-90

Mechanical engineering interview questions with answers which are asked by HR and in technical rounds.

81)   What are the factors that affect the material removal rate in AJM process?
Ans) Mass flow rate
        Abrasive grain size
        Gas pressure
        Velocity of abrasive particles
        Mixing ratio
        Nozzle tip clearance


82)   What is water jet machining process?
Ans) In WJM process high pressure and high velocity stream of water is used to cut the relatively
softer and non metallic material like paper board, wood , plastic, etc.


83)   State the working principle of hydrodynamic jet machining process
Ans) In HJM process abrasive particles are added to the high velocity stream of water jet and the
material is removed from the workpiece due to the combined effect of abrasion and water
impact

84)   List the unique benefits offered by water jet machining process.
Ans) In this process water is used as energy transfer medium. It is cheap, non toxic and easy to
dispose.
        Low operating cost
        The work area remains clean and dust free.
        Low maintenance cost

85)   List the disadvantage of WJM process.

Ans) Initial cost of WJM process is high

        It is difficult to machine hard materials.

86)   List the applications of WJM process.

Ans) This process is very convenient for cutting relatively softer and non metallic material like paper board, plastic, wood, rubber, leather, etc.

87)   Differentiate abrasive jet machining process and sand blasting process.

Ans) AJM is basically meant for metal removal with the use of small abrasive particles whereas the sand blasting process is a surface cleaning process which does not involve any metal cutting.

88)   State the working principle of ultra sonic machining process.

Ans) In USM process a slurry of small abrasive particles are forced against the work piece by means of vibrating tool and it causes the removal of metal from the work piece in the form of extremely small chips.

89)   What is meant by transducer?

Ans) Transducer is a device which converts one form of energy into another form of energy.

90)   What are the types of transducers used in ultrasonic machining process?

Ans) There are two types of transducers used in ultrasonic machining process for the production of ultrasonic waves. They are:

                           # Magnetostriction transducer

                           # Piezoelectric transducer    

Question 71-80

Mechanical engineering interview questions with answers which are asked by HR and in technical rounds.

71)   What are the abrasives used in AJM process?
Ans) The various abrasive particles used in AJM process are aluminum oxide, silicon carbide, glass powder dolomite and specially prepared sodium bicarbonate.

72)   What are the materials used for nozzle manufacturing in AJM process?
Ans) Tungsten carbide
        Synthetic sapphire

73)   What is the average life of nozzle made by Tungsten carbide?
Ans) 12-20 hours

74)   What is the average life of nozzle made by synthetic sapphire?
Ans) 300 hours


75)   Name the carrier gases used in AJM process?
Ans) Nitrogen
        Carbon dioxide
        Helium
        Compressed air

76)   What are the desirable properties of carrier gas in AJM
Ans) It should be cheap
        It should be non toxic
        It should be easily available
        It should dry quickly

77)   What are the transfer medium in AJM?
Ans) Nitrogen
        Carbon dioxide
        Helium
        Compressed air

78).  List any four advantages of AJM process.

Ans) # This process is suitable for cutting all materials.

        # Even diamond can be cut.

        # Initial investment is low.

        # It can be used to cut intricate hole shapes in hard materials.

79).  List any two disadvantages of AJM.

Ans) # Material removal rate is slow.

        # Soft material cannot be machined.

80).  What are the applications of AJM process?

Ans) #Machining hard and brittle materials like quartz.

        # Fine drilling

        # Microwelding

        # Machining of semiconductors.

Question 61-70

Mechanical engineering interview questions with answers which are asked by HR and in technical rounds.

61)   For threading operation which process is best suited?
Ans) EDM

62)   What type of energy source is applied in the Ion beam machining process?
Ans) Ionised substance

63)   What type of energy source is applied in electro chemical machining process?
Ans) Electric current

64)   State the type of energy source applied in chemical machining process?
Ans) Corrosive agent

65)   What type of energy source is applied in electro chemical grinding process?
Ans) Electrical current and mechanical motion

66)   What type of energy source is applied in electrical discharge machining process?
Ans) Electrical spark

67)   State the type of energy source applied in electron beam machining process.
Ans) High speed electrons

68)   What type of energy source is applied in abrasive jet machining process?
Ans) Mechanical and fluid motion

69)   What type of energy source is applied in laser beam machining process?
Ans) Power radiation

70)   State the working principle of abrasive jet machining.
Ans) In AJM process a high speed stream of abrasive particle mixed with high pressure air or gas are
        injected through a nozzle on the work piece to be machined.

Question 51-60

Mechanical engineering interview questions with answers which are asked by HR and in technical rounds.

51)   Name the unconventional machining process for machining steel
Ans) ECM
        CHM
        EDM
        PAM

52)   For producing micro holes which process is best suited?
Ans) Laser beam machining LBM

53)   For machining small holes which process is best suited?
Ans) Electron beam machining EBM

54)   For machining deep holes which process is well suited?
Ans) Electro chemical machining ECM

55)   For producing shallow holes which process are best suited?
Ans) Ultrasonic machining USM
        Electro discharge machining EDM

56)   For precision through cavities in workpieces which processes are well suited?
Ans) USM
        EDM

57)   Name the unconventional machining processes which produce best surface finish
Ans) Abrasive jet machining AJM
        Electro chemical grinding ECG
        Electro chemical deburring ECD
        Ultrasonic machining USM


58)   For grinding operation which processes are best suited?
Ans) AJM
        EDM

59)   For honing operation which process is well suited ?
Ans) ECM

60)   For deburring operation which processes are best suited?
Ans) USM
        AJM

Question 41-50

Mechanical engineering interview questions with answers which are asked by HR and in technical rounds.

41)   List the unconventional machining process which uses thermal or heat energy
Ans) Laser beam machining LBM
        Plasma arc machining PAM
        Electron beam machining EBM
        Ion beam machining IBM

42)   List the unconventional machining process which uses electro chemical energy
Ans) Electro chemical machining ECM
        Electro chemical grinding ECG
        Electro chemical honing ECH
        Electro chemical deburring ECD

43)   Name the unconventional machining process which are used to remove maximum material
Ans) Electro chemical machining ECM
        Plasma arc machining PAM


44)   Name the unconventional machining process which is used to remove minimum material
Ans) Electron beam machining EBM

45)   Name the unconventional machining process which consumes maximum power
Ans) Laser beam machining LBM

46)   Name the unconventional machining process which consumes minimum power
Ans) Plasma arc machining PAM

47)   Name the unconventional machining process for machining non metals like ceramic, plastic and
        glass.
Ans) Ultrasonic machining USM
         Abrasive jet machining AJM
         Laser beam machining LBM
         Electron beam machining EBM

48)   Name the unconventional machining process for machining refractories.
Ans) USM
        AJM
        EBM
        Electro discharge machining EDM

49)   Name the unconventional machining process for machining titanium
Ans) EDM

50)   Name the unconventional machining process for machining super alloys
Ans) AJM
        EDM
        PAM
        Electro chemical machining ECM

Question 31-40

Mechanical engineering interview questions with answers which are asked by HR and in technical rounds.

31)   What is meant by conventional machining process?

Ans) In conventional machining processes, metals are removed by using some sort of tools which is harder than the work piece & is subjected to wear. In this process the tool & the work piece are in direct contact with each other.

32)   What is unconventional machining process (UCMP)?

Ans) The unconventional machining process do not employ a conventional machining tool for metal removal, instead they directly utilize some form of energy for metal machining.In this process there is no direct contact between the toll and the work piece.

33)   What is thermal energy methods of UCMP?

Ans) In these methods heat energy is concentrated on a small area of the work piece to melt & vaporize the tiny bit of work material.

34)   Give some examples for thermal energy method of UCMP.
Ans)  Laser beam machining (LBM)
        Plasma arc machining (PAM)
        Electron beam machining (EBM)

35)   What is electro chemical energy method of unconventional machining?
Ans) In this method material is removed by ion displacement of the work piece material in contact
with a chemical solution.

36)   Example for electro chemical energy method of unconventional machining.
Ans) Electro chemical machining ECM
        Electro chemical grindin g ECG
        Electro chemical honing ECH

37)   What is chemical energy method of unconventional machining?
Ans) The chemical energy method involve controlled etching of the work piece material in contact
with a chemical solution.

38)   Example for chemical energy method of unconventional machining.
Ans) Chemical machining CHM

39)   Example for chemical energy method of unconventional machining
Ans) Chemical machining CHM

40)   Example for mechanical energy method of unconventional machining?
Ans) Ultrasonic machining USM
        Abrasive jet machining AJM
        Water jet machining WJM