Quiz: Mechanical Engineering
Exam: UPPSC Lecturer
Each question carries 1 mark
Negative marking: 1/4 mark
Time: 6 Minutes
Q1. Match List – I with List – II and select the correct answer using the code given below the List:
List – I List – II
A. Connecting rods 1. Welding
B. Pressure vessels 2. Extrusion
C. Machine tool beds 3. Forging
D. Collapsible tubes 4. Casting
A B C D
(a) 2 1 4 3
(b) 3 1 4 2
(c) 2 4 1 3
(d) 3 4 1 2
Q2. Which of the following is the correct statement about an indirect hot extrusion process?
1. Billet remains stationary
2. There is no friction force between billet and container walls
3. The force required on the punch is more in comparison to direct extrusion
4. Extruded parts have to be provided a support
(a) 1, 2, 3 and 4
(b) 1, 2 and 3 only
(c) 1, 2 and 4 only
(d) 2, 3 and 4 only
Q3. The diameter of a hole is 20 mm is to be punched in a sheet metal of thickness t and ultimate shear strength 100 MPa, using punching force of 44 kN.
The maximum value of ‘t’ is
(a) 7.5 mm
(b) 10 mm
(c) 7 mm
(d) 0.7 mm
Q4. In wire – drawing operation, the maximum reduction per pass for perfectly plastic material in ideal condition is
(a) 68 %
(b) 63 %
(c) 58 %
(d) 50 %
Q5. Rotary swaging is a process for shaping
(a) round bars and tubes
(d) rectangular blocks
Q6. Scab is a
(a) sand casting defect
(b) machining defect
(c) welding defect
(d) forging defect
Sol. Connecting rods are made by forging process
Pressure vessels are made by welding
Machine tool bed are made by casting
Collapsible tubes are made by extrusion
Welding is a process of joining metals either by melting or by the plastic deformation of with or without the application of pressure.
Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn through a hole of the desired cross-section. The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections and work materials that are brittle as well as ductile, because the material only encounters compressive and shear stresses.
Casting is a manufacturing process by which a liquid material is usually poured into a mold cavity, of the desired shape, and then allowed to solidify it.
Sol. The following points are the advantages of indirect extrusion
1. As compare to direct extrusion, 25 – 30% reduction in maximum load.
2. Extrusion pressure is not a function of billet length.
3. No friction between billet and container in indirect extrusion.
4. Tool has higher service life in indirect extrusion.
Sol. τ_ult = F/πdt
∴ t = F/(πdτ_ult ) =(7×44×10^3 )/(22×20×100) = 7 mm
Sol. Maximum possible reduction per pass in wire drawing process is 63.2%.
Sol. Rotary swagging is a process for shaping round bars and tubes.
Sol. Scab is a sand-casting defect.