Manufacturing Engineering Questions & Answers – Introduction To Forging and Extrusion Process

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This set of Manufacturing Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Introduction To Forging”.

1. Shaping of metal by squeezing them in between two or more dies in order to obtain desire shape is done by?
a) Forming
b) Forging
c) Welding
d) Grinding
View Answer

Answer: b
Explanation: Forging is the term applied to a family of processes where deformation is induced by localized compressive forces. The forging material may be drawn out to increase its length and decrease its cross section upset to decrease the length and increase the cross section squeezed in closed impression dies to produce multidirectional flow.
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2. Forging is carried out at which temperature?
a) Below recrystallization temperature
b) Above recrystallization temperature
c) Below or above recrystallization temperature
d) Above melting point
View Answer

Answer: c
Explanation: Forging is the process of forming. It is of two types, hot and cold forging. Hot forging is done by heating a metal to about 60-65% of its melting temperature, thus above recrystallization temperature. Cold forging is generally used with soft metals, usually done at room temperature, thus below recrystallization temperature.

3. Which of the following is a type of forging?
a) Open die
b) Closed die
c) Impression dies
d) Hold dies
View Answer

Answer: d
Explanation: There are basically three methods (or processes) to make a forged part, i. Impression die forging, ii. Closed die fording, iii. Open die forging. Some people call impression die forging too as closed die forging, and it is acceptable to call the same sometimes. Impression die forging pounds or presses metal between two dies (called tooling) that contain a pre-cut profile of the desired part. In closed die forging the work piece is deformed between two die halves which carry the impression of the desired final shape. The open die forging is carried out between two flat dies or simple shapes.

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4. In which of the following forging metal is kept in the lower die?
a) Open die
b) Closed die
c) Impression dies
d) Hold dies
View Answer

Answer: a
Explanation: When shaping a solid piece of metal by closed die forging, the die is initially open. The work piece is placed in the lower die half, and the top die is then brought down to engage with the work piece The application of pressure between the slowly closing die halves causes the solid to flow plastically within the constrains of the die, being displaced to fill the outer sections of the die cavity.

5. In which of the forging process metal is kept in between a pair of dies and a gutter is provided in the lower die?
a) Open die
b) Closed die
c) Impression dies
d) Hold dies
View Answer

Answer: b
Explanation: In closed die forging process metal is kept in between a pair of dies and a gutter is provided in the lower die. In impression die forging process metal is kept in between a pair of dies and no gutter is provided in the lower die.
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6. In which of the forging process metal is kept in between a pair of dies and no gutter is provided in the lower die?
a) Open die
b) Closed die
c) Impression dies
d) Hold dies
View Answer

Answer: c
Explanation: Sometimes, the closed die forging is also termed as impression die forging. In this impression are made in a pair of dies. These impressions are transferred to the work piece during deformation. A small gap between the dies called flash gutter is provided, so that, the excess metal can flow into the gutter and form a flash.

7. The extra metal which settles down in the gutter is known as?
a) Flash
b) Slag
c) Flux
d) Barrelling
View Answer

Answer: a
Explanation: In impression die forging, the die surfaces contain a shape that is given to the work piece during compression, thus restricting the metal flow significantly. There is some extra deformed material outside the die impression which is called as flash. This will be trimmed off later.
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8. In which of the following forging process no flash is formed?
a) Open die
b) Closed die
c) Impression dies
d) Hold dies
View Answer

Answer: b
Explanation: In flashless forging, the work piece is fully restricted within the die and no flash is produced. The amount of initial work piece used must be controlled accurately so that it matches the volume of the die cavity.

9. In which of the following forging process poor material utilization occurs?
a) Open die
b) Closed die
c) Impression dies
d) Hold dies
View Answer

Answer: a
Explanation: In the case of open die forging, lower material utilization, machining of the final shape is necessary, slow production rate, low lead times, commonly used for one-offs and high usage of skilled labour.
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10. Cogging, which is also called as drawing out, is basically?
a) Open die forging operation
b) Closed die forging operation
c) Impression dies forging operation
d) Hold die forging operation
View Answer

Answer: a
Explanation: Cogging is an open die forging process in which flat or slightly contoured die are employed to compress a work piece, reducing its thickness and increasing its length.

11. In rolling operation, the roll rotates with surface velocity?
a) exceeding the speed of incoming metal
b) lower than the speed of incoming metal
c) equal to speed of the incoming metal
d) Very higher than the speed of incoming metal
View Answer

Answer: c
Explanation: The rolls rotate with a surface velocity exceeding the speed of the incoming metal, friction along the contact interface acts to propel the metal forward. The metal is squeezed and elongated and usually changed in cross section.

12. A round billet made of 70-30 brass is extruded at a temperature of 675°C. The billet diameter is 125 mm, and the diameter of the extrusion is 50 mm. Calculate the extrusion force required.
a) 4 MN
b) 5 MN
c) 5.6 MN
d) none of the mentioned
View Answer

Answer: c
Explanation: The extrusion force is calculated using
Eq. F = A0k ln(A0/Af)
in which the extrusion constant, k, is obtained.
For 70-30 brass, k = 250 MPa at the given extrusion temperature. Thus,
F = (3.14(125)2)/4 x (250) ln [(3.14(125)2)/(3.14(50)2)] = 4
= 5.6 MN.

13. In which type of extrusion, a billet is placed in a chamber?
a) forward
b) indirect
c) hydrostatic
d) impact
View Answer

Answer: a
Explanation: In forward extrusion, a billet is placed in a chamber and forced through a die opening by a hydraulically driven ram. The die opening may be round, or it may have various shapes, depending on the desired profile.

14. In which type of extrusion, the die moves toward the unextruded billet?
a) forward
b) indirect
c) hydrostatic
d) impact
View Answer

Answer: b
Explanation: In indirect extrusion, (also called reverse, inverted, or backward extrusion), the die moves toward the unextruded billet. Indirect extrusion has the advantage of having no billet-container friction, since there is no relative motion.

15. In which type of extrusion, the billet is smaller in diameter than the chamber?
a) forward
b) indirect
c) hydrostatic
d) impact
View Answer

Answer: c
Explanation: In hydrostatic extrusion, the billet is smaller in diameter than the chamber (which is filled with a fluid), and the pressure is transmitted to the fluid by a ram.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter