This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Electromagnetic Forming”.
1. In electromagnetic forming, highly intense magnetic field is used for the forming process.
a) True
b) False
View Answer
Explanation: In electromagnetic forming, many components like capacitor bank, forming coil, field shaper, conductive material etc. are used to create intense magnetic fields. This magnetic is generally produced by the discharge of capacitors into a coil, which lasts only for a few microseconds. Then further processing is done to perform the metal forming.
2. The magnetic field interacts with metal to generate heat in the metal which causes forming process.
a) True
b) False
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Explanation: In the electromagnetic forming process, eddy currents are induced in a conductive material that is placed near to the coil. Then it interacts with a magnetic field to cause mutual repulsion between the metal and the forming coil. This force of repulsion is mainly responsible for inducing stresses in the metal beyond its yield strength which results in plastic deformation of metal.
3. Metal used for electroforming process absorbs energy from the magnetic field to get deform.
a) True
b) False
View Answer
Explanation: In the electromagnetic forming process, the conductivity of the metal and the eddy currents which makes contact with magnetic field creates a net pressure on the surface of the metal. Then the metal surface moves inward due to the effect of this pressure, this mainly occurs due to the transfer of energy from the magnetic field to the metal.
4. In the electromagnetic forming process, the forming pulse is kept longer to optimize the use of energy.
a) True
b) False
View Answer
Explanation: In the electromagnetic forming process, the metal absorbs energy from the magnetic field to get deformed. To utilize most of this energy to forming operation, and to reduce the energy loss due to resistance heating, the forming pulse is kept short for better optimization of energy produced by the magnetic field. In general, pulse has duration of between 10 and 100 second.
5. Which of the following methods of forming is not the part of electromagnetic forming?
a) Compression
b) Expansion
c) Shearing
d) Counter forming
View Answer
Explanation: In the electromagnetic forming process, electromagnetic formation mainly used for three forming methods which can be compression, expansion, and counter forming. For compression, a tubular metal is compressed by a coil, usually against a grooved tube. And shearing is a different process which is not a part of electromagnetic forming.
6. Electromagnetic forming cannot be used for materials of poor electrical conductivity.
a) True
b) False
View Answer
Explanation: The electromagnetic forming method uses a high intense magnetic field to deform the material. This process is primarily used for the forming of good conducting materials like copper, aluminum, silver etc. This method can also be used for materials of poor electrical conductivity such as stainless steel.
7. The efficiency of electromagnetic forming mainly depends on the resistivity of material being formed.
a) True
b) False
View Answer
Explanation: The electromagnetic forming method uses a capacitor and forming coil to create intense magnetic field. The efficiency of the magnetic pulse mainly depends on the resistivity of the material being formed. For better output, the resistivity of the material must be less than 15 micro-ohm-centimeters.
8. The process of electromagnetic forming does not require any kind of lubrication.
a) True
b) False
View Answer
Explanation: In most of the forming processes, tool contacts with the specimen to get the desired output. But in the case of electromagnetic forming, the magnetic field is used to apply the pressure on the surface of a metal, which normally does not require any kind of lubrication. And it leaves no any tool marks on the metal surface.
9. Which of the following is the main advantage of using the electromagnetic forming process?
a) High speed
b) Low maintenance
c) Applicable to all materials
d) No spring-back
View Answer
Explanation: In the electromagnetic forming process, the metal is loaded and achieve plastic region, which results in plastic or permanent deformation, so that the spring-back associated with the mechanical forming process is completely eliminated because no any mechanical contact is present during the process of metal forming.
10. The joints made by an electromagnetic forming process are much stronger than the parent material.
a) True
b) False
View Answer
Explanation: In the electromagnetic forming process, the joints made are much stronger than the parent material. This process also allows increased ductility for several alloys because of the lack of stresses and friction which normally encountered with the process. This method is widely used for a high rate of production.
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