This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Extrusion in Polymers”.
1. Which of the following material is not used in extrusion?
a) Wax
b) Granules
c) Powder
d) Pellets
View Answer
Explanation: Extrusion is a process of forcing plastic which is at a very high temperature, through the dies, and gets opened at a required shape. The raw materials used for extrusion with polymers contain granules, powder and thermoplastic pellets.
2. In extrusion process, extra shearing occurs in which part of the system?
a) Feed section
b) Pumping section
c) Collapse section
d) Transition section
View Answer
Explanation: The section where an additional amount of melting and shearing occurs is called a pumping section.
3. Melting section is another name for which section?
a) Feed section
b) Transition section
c) Pumping section
d) Collapse section
View Answer
Explanation: Melting section is one of the types of extrusion in polymers. Extrusion is a process of forcing plastic which is at a very high temperature, through the dies, and gets opened at a required shape. Melting section is another name for transition section.
4. How are extruded materials cooled?
a) Water
b) Contact with chilled surface
c) Air
d) Oil
View Answer
Explanation: On completion of extrusion, the material is very hot and has to be cooled down. There are various agents which are used cooling these materials down, such as, air or water or its direct contact with a very cold surface.
5. Which of the following is not an important factor of cooling in extrusion?
a) Reduction in shrinkage
b) Reduction in distortion
c) Ease of adding colours
d) Rate of cooling
View Answer
Explanation: There are various factors of cooling, a few of them are, reduction in shrinkage, reduction in distortion and the rate of cooling too has to be considered.
6. Which of the following is not an application of polymer extrusion?
a) Door insulation seals
b) Chewing gums
c) Cables
d) Circuit boards
View Answer
Explanation: Circuit boards is not an application of polymer extrusion. Door insulation seals, chewing gums and cables are the applications of polymer extrusion.
7. Film extrusion process, best involves film having a thickness below what length?
a) 0.2 mm
b) 0.3 mm
c) 0.4 mm
d) 0.5 mm
View Answer
Explanation: Extrusion of films is one of the most important processes in extrusion. For the films having a thickness below 0.5 mm, these films are best suited for extrusion and can be further applied for making various bags.
8. In the cable extrusion process, what is the speed of product winding?
a) 40 m/sec
b) 50 m/sec
c) 60 m/sec
d) 70 m/sec
View Answer
Explanation: For the insulation purpose, the coating of any wire or cable is one of the most vital polymer extrusion process. The wire is cooled and then it is wound to large spools at a speed of 50 meters per second.
9. Calendering is mostly suited for making PVC.
a) True
b) False
View Answer
Explanation: Calendering process is considered to be one of the most important sheet forming process. Calendering has many products like phenyl, cellulose or vinyl floor tiles. It is most suited for making PVCs.
10. Tubes having U shape cannot be manufactured by polymer extrusion process.
a) True
b) False
View Answer
Explanation: Polymer extrusion has a variety of applications such as candy canes, chewing gums, window frames, solid rods, pipes or tubes having U or J sections.
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