Manufacturing Processes Multiple Choice Questions on “Friction Welding – 1”.
1. Friction welding produces welds due to ______
a) electrode melting
b) workpiece melting
c) relative motion between workpieces
d) adhesive force between workpiece particles
Answer: c
Clarification: Friction Welding (FRW) is a solid state welding process which produces welds due to the compressive force contact of workpieces which are either rotating or moving relative to one another.
2. In friction welding, material is deformed due to_____
a) elastic deformation
b) plastic deformation
c) ductile deformation
d) brittle deformation
Answer: b
Clarification: In friction welding the heat required to produce the joint is generated by friction heating at the interface. This heat displaces material plastically from the faying surfaces.
3. Which of the following is true about friction welding?
a) One workpiece is held stationary while the other is moving
b) Both the workpieces are moving
c) Both the workpieces are stationary and filler is added in the space between them
d) The material is deformed elastically
Answer: a
Clarification: The components to be joined are first prepared to have smooth, square cut surfaces. One piece is held stationary while the other is mounted in a motor driven chuck or collet and rotated against it at high speed.
4. During friction welding, initially low pressure is applied. Why?
a) For slowly increasing the surface temperature
b) For melting the surface coating on the materials
c) To check weldabilty of two materials
d) For initial cleaning of the surface
Answer: d
Clarification: A low contact pressure may be applied initially to permit cleaning of the surfaces by a burnishing action. This pressure is then increased and contacting friction quickly generates enough heat to raise the abutting surfaces to the welding temperature.
5. After the welding temperature is reached _____
a) rotation is stopped
b) speed of rotation is increased
c) rotation of first workpiece is stopped and second workpiece starts rotating
d) filler material is added
Answer: a
Clarification: As soon as the welding temperature is reached, rotation is stopped and the pressure is maintained or increased to complete the weld. The softened material is squeezed out to form a flash. If desired, the flash can be removed by subsequent machining action.
6. By friction welding, steel bars upto _____ mm diameter can be welded.
a) 10
b) 50
c) 100
d) 210
Answer: c
Clarification: During friction welding, a forged structure is formed in the joint. Friction welding has been used to join steel bars upto 100 mms in diameter and tubes with outer diameter upto 100 mm.
7. Inertia welding is a modified form of friction welding.
a) True
b) False
Answer: a
Clarification: Inertia welding is a modified form of friction welding, where the moving piece is attached to a rotating flywheel. The flywheel is brought to a specified rotational speed and is then separated from the driving motor.
8. Which of the following is not true about inertia welding?
a) Weld is formed when the flywheel stops
b) The process is difficult for automation
c) Weld quality is consistent
d) Parts remain in contact even after the weld is completed
Answer: b
Clarification: The weld is formed when the flywheel stops its motion and the pieces remain pressed together. Since the conditions of the inertia welding are easily duplicated, welds of consistent quality can be produced and the process can be easily automated.
9. During friction welding, shielding gases are needed.
a) True
b) False
Answer: a
Clarification: Following are the advantages of friction welding;
• No filler material is needed
• No shielding gases or flux is needed
• It is smoke free process
• The process is in solid state with a narrow heat affected zone.
10. Which of the following is not true?
a) Oxides can be removed after the welding process
b) Automation is possible
c) Rapid welds are made
d) Process can be used for limited materials
Answer: d
Clarification: Following are the advantages of friction welding;
• Oxides can be removed after the welding process
• In most cases, the weld strength is stronger that the weaker of the two materials
• The process can be easily automated for mass production
• The process is very efficient and comparatively very rapid welds are made
• Wide variety of metals and combinations can be welded.