This set of Manufacturing Processes Multiple Choice Questions & Answers (MCQs) focuses on “Friction Welding – 3”.
1. In friction welding process, materials are joined by _____ motion between materials.
Explanation: Friction welding is a solid-state joining process that produces coalescence in materials, using the heat developed between surfaces through a combination of mechanically induced rubbing motion and applied load. The resulting joint is of forged quality.
2. All metallic engineering materials which are _____ can be friction welded.
Explanation: As a rule, all metallic engineering materials which are forgeable can be friction welded, including automotive valve alloys, maraging steel, tool steel, alloy steels and tantalum. In addition, many castings, powder metals and metal matrix composites are weldable.
3. Friction welding is _____ process.
b) cost saving
c) time consuming
d) highly material selective
Explanation: Since dissimilar materials can be joined, a significant cost savings are possible because engineers can design bimetallic parts that use expensive materials only where needed. Expensive forgings and castings can be replaced with less expensive forgings welded to bar stock, tubes, plates and the like.
4. Friction welding produces quality joints, with a 100% _____ weld.
a) lap joint
c) butt joint
d) edge joint
Explanation: Friction welding produces forged quality joints, with a 100% butt joint weld through the contact area. Furthermore, in friction welding heat affected zone is much narrower as compared to other welds, which indeed reduces the cost of post-weld heat treatments (stress relieving processes).
5. Which of the following is not true about friction welding?
a) Dissimilar metals cannot be joined
b) This technique is relatively faster as compared to the other techniques
c) This technique is suitable for any parts of shape or size
d) Sheared surfaces can also be joined by the process
Explanation: Following are the few advantages of friction welding over other techniques:
• Dissimilar metals are joined, even some considered incompatible or unweldable.
• The process is at least twice— and up to 100 times—as fast as other welding techniques.
• Friction welders are versatile enough to join a wide range of part shapes, materials and sizes.
• Joint preparation isn’t critical… machined saw cut, and even sheared surfaces are weldable.
6. Which of the following holds true for friction welding?
a) Hazardous fumes are generated during the process
b) Argon is used as a shielding gas
c) It is a power consuming process
d) There are no solidification defects in the welded parts
Explanation: Following are the few reasons to consider friction welding over other techniques:
• The machine-controlled process eliminates human error, and weld quality is independent of operator skill.
• It’s ecologically clean—no objectionable smoke, fumes, or gases are generated that need to be exhausted.
• No consumables are required— no flux, filler material, or shielding gases.
• Power requirements are as low as 20% of that required of conventional welding processes.
• Since there is no melting, no solidification defects occur, e.g. gas porosity, segregation or slag inclusions.
7. In inertia friction welding ______ energy of welding machine is used.
Explanation: Inertia Friction Welding is a variation of friction welding in which the energy required to make the weld is supplied primarily by the stored rotational kinetic energy of the welding machine.
8. In inertia friction welding, one workpiece is connected to _____
b) the pin tool
Explanation: In Inertia Welding, one of the workpieces is connected to a flywheel and the other is restrained from rotating. The flywheel is accelerated to a predetermined rotational speed, storing the required energy. The drive motor is disengaged and workpieces are forced together by the friction welding force.
9. Weld strength in inertia friction welding is more than direct drive friction welding.
Explanation: Inertia Friction Welding has the following advantages over the Direct Drive Friction Welding process:
• Helical flow lines and hot working at end of weld cycle can help in weld strength
• Ease of monitoring, given only two variables for welding: energy (RPM) and pressure. Energy can be monitored before a signal is given to weld reducing the variables during welding to one
• Weld torque is measured indirectly by measuring the rate of spindle speed change.
10. In direct drive friction welding, lower weld forces are generated.
Explanation: Following are the advantages of direct drive friction welding over inertia friction welding:
• Lower weld force for solid parts. Larger parts can be welded on same tonnage machine
• Lower weld torque if brake is applied at end of weld cycle. Tooling requirements are, therefore, less rigid
• Lower RPM for solid parts
• No flywheel change between setups.
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