Joining of Materials - Manufacturing Processes I - Production & Industrial Engineering Previous Year Questions

1

2007 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2007

The figure below shows the cross-section of circular fillet weld joining a cylindrical steel pin to a steel plate. If the pin is subjected to a pure torsional load, the shear stress (MPa) occurring at the throat of the weld is

A

2.5

B

5.0

C

7.0

D

10

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2

2007 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2007

The D.C. power source for arc welding has the characteristic \( 3V + I = 240 \), where V = Voltage and I = Current in amp. For maximum arc power at the electrode, voltage should be set at

A

20 V

B

40 V

C

60 V

D

80 V

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3

2008 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2008

Which pair among the following solid state welding processes uses heat from an external source?
P - Diffusion welding; Q - Friction welding; R - Ultrasonic welding; S - Forge welding

A

P and R

B

R and S

C

Q and S

D

P and S

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4

2008 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2008

Aluminium strips of 2 mm thickness are joined together by resistance spot welding process by applying an electric current of 6000 A for 0.15 sec. The heat required for melting aluminium is 2.9 J/mm³. The diameter and the thickness of weld nugget are found to be 5 mm and 2.5 mm, respectively. Assuming the electrical resistance to be 75 micro-ohms, the percentage of total energy utilized in forming the weld nugget is

A

28

B

35

C

65

D

72

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5

2009 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2009

Which of the following powders should be fed for effective oxy-fuel cutting of stainless steel ?

A

Steel

B

Aluminum

C

Copper

D

Ceramic

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6

2009 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2009

Autogenous gas tungsten arc welding of a steel plate is carried out with welding current of 500 A, voltage of 20 V, and weld speed of 20 mm/min. Consider the heat transfer efficiency from the arc to the weld pool as 90%. The heat input per unit length (in kJ /mm) is

A

0.25

B

0.35

C

0.45

D

0.55

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7

2009 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2009

Heat (in Joules) used for producing weld nugget will be (assuming 100% heat transfer efficiency)

A

324

B

334

C

344

D

354

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8

2009 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2009

Heat (in Joules) dissipated to the base metal will be (neglecting all other heat losses)

A

10

B

16

C

22

D

32

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9

2010 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2010

Two steel bars, each of diameter 10 mm, are coaxially friction welded, end to end, at an axial pressure of 200 MPa and at a rotational speed of 4000 rpm. The coefficient of friction between the mating faces of the rotating bars is 0.50. The torque is assumed to act at the 3/4th radius of the rotating bar. The power (in kW) consumed at the interface for welding is

A

12.33

B

16.44

C

18.50

D

24.66

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10

2010 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2010

During a steady gas metal arc welding with direct current electrode positive polarity, the welding current, voltage and weld speed are 150 A, 30 V and 6 m/min, respectively. A metallic wire electrode of diameter 1.2 mm is being fed at a constant rate of 12 m/min. The density, specific heat and melting temperature of the wire electrode are 7000 kg/m³, 500 J/kgK and 1530°C, respectively. Assume the ambient temperature to be 30°C and neglect the latent heat of melting. Further, consider that two-third of the total electrical power is available for melting of the wire electrode. The melting efficiency (in percentage) of the wire electrode is

A

39.58

B

45.25

C

49.38

D

54.98

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11

2010 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2010

During a steady gas metal arc welding with direct current electrode positive polarity, the welding current, voltage and weld speed are 150 A, 30 V and 6 m/min, respectively. A metallic wire electrode of diameter 1.2 mm is being fed at a constant rate of 12 m/min. The density, specific heat and melting temperature of the wire electrode are 7000 kg/m³, 500 J/kg°C and 1530°C, respectively. Assume the ambient temperature to be 30°C and neglect the latent heat of melting. Further, consider that two-third of the total electrical power is available for melting of the wire electrode. The melting efficiency (in percentage) of the wire electrode is

A

39.58

B

45.25

C

49.38

D

54.98

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12

2010 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2010

A 1 m long cylindrical shaft of diameter 100 mm is joined to the wall by means of fillet weld as shown in the following figure. The shaft is designed to carry a torque of 5 kNm at the free end. If the allowable shear stress of the weld material is 80 MPa, then the minimum value of the size, L (shown in the following figure), of the fillet (in mm) is

A

3.97

B

5.63

C

7.95

D

11.45

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13

2011 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2011

In resistance seam welding, the electrode is in the form of a

A

cylinder

B

flat plate

C

coil of wire

D

circular disc

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14

2012 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2012

In a DC arc welding operation, the voltage-arc length characteristic was obtained as \(V_{arc} = 20 + 5l\) where the arc length \(l\) was varied between \(5 mm\) and \(7 mm\). Here \(V_{arc}\) denotes the arc voltage in Volts. The arc current was varied from \(400 A\) to \(500 A\). Assuming linear power source characteristic, the open circuit voltage and the short circuit current for the welding operation are

A

45 V, 450 A

B

75 V, 750 A

C

95 V, 950 A

D

150 V, 1500 A

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15

2013 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2013 [Session 2]

A single riveted lap joint of two similar plates as shown in the figure below has the following geometrical and material details.
plate width \( w = 200 \, mm \)
plate thickness \( t = 5 \, mm \)
number of rivets \( n = 3 \)
rivet diameter \( d_r = 10 \, mm \)
rivet hole diameter \( d_h = 11 \, mm \)
allowable tensile stress of plate \( \sigma_p = 200 \, MPa \)
allowable bearing stress of rivet \( \sigma_c = 150 \, MPa \)
If the plates are to be designed to avoid tearing failure, the maximum permissible load \( P \) in \( kN \) is

A

83

B

125

C

167

D

501

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16

2014 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2014

Brazing and Soldering are

A

plastic joining methods

B

homogeneous joining methods

C

autogenous joining methods

D

heterogeneous joining methods

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17

2014 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2014

In an arc welding operation, carried out with a power source maintained at 40 volts and 400 amperes, the consumable electrode melts and just fills the gap between the metal plates to be butt-welded. The heat transfer efficiency for the process is 0.8, melting efficiency is 0.3 and the heat required to melt the electrode is 20 J/mm³. If the travel speed of the electrode is 4 mm/s, the cross-sectional area, in mm², of the weld joint is ______

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18

2016 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2016

In linear gas tungsten arc welding of two plates of the same material, the peak temperature \(T\) (in K) is given as \(T = \frac{C_1 q}{\alpha}\), where \(q\) is the heat input per unit length (in J/m) of weld, \(\alpha\) is the thermal diffusivity (in m²/s) of the plate materials and \(C_1\) is a constant independent of process parameters and material types. Two welding cases are given below. Case I: \(V = 15\) V, \(I = 200\) A, \(v = 5\) mm/s, \(k = 150\) W/mK, \(\rho = 3000\) kg/m³, \(C = 900\) J/kg·K Case II: \(V = 15\) V, \(I = 300\) A, \(v = 10\) mm/s, \(k = 50\) W/mK, \(\rho = 8000\) kg/m³, \(C = 450\) J/kg·K where, \(V\) is welding voltage, \(I\) is welding current, \(v\) is welding speed, and \(k\), \(\rho\) and \(C\) refer to the thermal conductivity, the density and the specific heat of the plate materials, respectively. Consider that electrical energy is completely converted to thermal energy. All other conditions remain same. The ratio of the peak temperature in Case I to that in Case II is

A

\(\frac{1}{3}\)

B

\(\frac{1}{2}\)

C

1

D

2

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19

2016 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2016

Two flat steel sheets, each of 2.5 mm thickness, are being resistance spot welded using a current of 6000 A and weld time of 0.2 s. The contact resistance at the interface between the two sheets is 200 μΩ and the specific energy to melt steel is 10×10⁹ J/m³. A spherical melt pool of diameter 4 mm is formed at the interface due to the current flow. Consider that electrical energy is completely converted to thermal energy. The ratio of the heat used for melting to the total resistive heat generated is ______.

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20

2017 · Production & Industrial Engineering · Manufacturing Processes I · Joining of Materials

Production & Industrial Engineering (PI) 2017

In gas tungsten arc welding process, the material coated on pure tungsten electrode to enhance its current carrying capacity is

A

Titanium

B

Manganese

C

Radium

D

Thorium

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