Materials Science and Manufacturing Engineering Miscellaneous Easy Questions and Answers | Page - 49

Materials Science and Manufacturing Engineering Miscellaneous

Autogeneous 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

1. 27
1. 35
1. 45
1. 55

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Current = 500 A
Voltage = 20 V
V = 20 mm/min
η_HT = 0.9
Heat Input/length = η_HT V × I = 0.9 × 20 × 500
N 20/60

= 27 kJ/mm

Correct Option: A

Current = 500 A
Voltage = 20 V
V = 20 mm/min
η_HT = 0.9
Heat Input/length = η_HT V × I = 0.9 × 20 × 500
N 20/60

= 27 kJ/mm

Group-I
P. Arc welding
Q. Friction welding
R. Solid state Welding
S. Laser welding
Group-II
1. Diffusion
2. Polarity
3. Focusing
4. Kinetic energy

1. P Q R S
  4 1 3 2
1. P Q R S
  3 2 4 3
1. P Q R S
  1 2 4 3
1. P Q R S
  2 4 1 3

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Arc welding - Polarity
Friction welding - Kinetic energy
Solid state welding - Diffusion
Laser welding - Focusing

Correct Option: D

Arc welding - Polarity
Friction welding - Kinetic energy
Solid state welding - Diffusion
Laser welding - Focusing

Circular blanks of 35 mm dia are punched from a steel sheet of 2 mm thickness. If the clearance per side between the punch and die is to be kept as 40 microns. The sizes of punch and die should respectively be

1. 35 and 35.040
1. 34.92 and 35
1. 35 and 35.080
1. 35.040 and 34.92

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Dia of Die = 35 mm
Dia of Punch = 35 – 2 × 0.04 = 34.92mm

Correct Option: B

Dia of Die = 35 mm
Dia of Punch = 35 – 2 × 0.04 = 34.92mm

Direction: A cup is to be drawn to a diameter of 70 mm with 35 mm depth from a 0.5 mm thick sheet metal. The cup is drawn in one operation. Assume σ_u = 430 MPa.

The required blank diameter is

1. 86.7 mm
1. 119.5 mm
1. 121.24 mm
1. 169 mm

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√d² + 4dh
= √70² + (4 × 70 × 35)
D = 121.24 mm

Correct Option: C

√d² + 4dh
= √70² + (4 × 70 × 35)
D = 121.24 mm

A cylindrical cup of 48.5 mm diameter and 52 mm height has a corner radius of 1.5 mm. Cold rolled steel sheet of thickness 1.5 mm is used to produce the cup. Assume trim allowance as 2 mm per 25 mm of cup diameter. What is the blank size in mm?

1. 102.0
1. 115.4
1. 120.5
1. 128.5

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= √d² + 4dh
D = √(48.5)² + 4 × 48.5 × 52
D = 111.53 mm
Trim Allowance = 2/25 × 48.5 = 3.88 mm.
Total blank size = 111.53 + 3.88 = 115.41 mm

Correct Option: B

= √d² + 4dh
D = √(48.5)² + 4 × 48.5 × 52
D = 111.53 mm
Trim Allowance = 2/25 × 48.5 = 3.88 mm.
Total blank size = 111.53 + 3.88 = 115.41 mm