This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Blow Moulding and Thermoforming “.
1. In blow molding, to inflate soft plastic, which medium is used?
a) Air
b) Water
c) Oil
d) Alcohol
View Answer
Explanation: Blow molding process is typically used for the blowing process of hollow plastics. While blow molding, the plastic has to be inflated, in order to do so, air has to be blown inside with a high amount of pressure.
2. Which of the following plastics is not used in blow molding?
a) Terephthalate
b) Polypropylene
c) Polythene
d) PVC
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Explanation: For blowing processes, there are certain plastics only which are properly suited for the operation, while any other material might fail. Hence, for operating through blow molding process, polypropylene, polythene and PVC are used.
3. What is the minimum air pressure required in blow molding process?
a) 350 kPa
b) 400 kPa
c) 450 kPa
d) 500 kPa
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Explanation: In blow molding process, there is some amount of pressure that has to be given to the air for blowing the bottles. The amount of pressure to be given depends on the material. The minimum pressure that can be given in this process is 400 kPa.
4. What can be the maximum pressure to be given to a plastic for blow molding process?
a) 700 kPa
b) 750 kPa
c) 800 kPa
d) 850 kPa
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Explanation: Air with an extreme amount of pressure, when is needed, it might mean the material is thicker and denser. The amount of pressure that can be provided depends totally on the material. The maximum pressure that can be provided in blow molding process is 800 kPa.
5. Which of the following is not a type of blow molding process?
a) Injection blow molding
b) Extrusion blow molding
c) Multi-smaller blow molding
d) Multi-larger blow molding
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Explanation: Blow molding basically is a process of inflation of air under pressure into the plastics inside the mold cavity. There are only three known types of blow molding, namely, injection blow molding, extrusion blow molding and multi larger blow molding.
6. What is the minimum thickness required by the plastic for vacuum forming?
a) 0.125 mm
b) 0.25 mm
c) 0.375 mm
d) 0.5 mm
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Explanation: Vacuum forming is one of the classifications of thermoforming processes. Around its circumference, a clamp is attached or which we need to know the minimum thickness. The minimum thickness that can be allowed for this operation is 0.125 mm.
7. Which of the following is not an application of blow molding process?
a) Toy bodies
b) Door liners
c) Bottles
d) Pipes
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Explanation: Among the following, only door liners is not an application of blow molding process. Internal door liners are made using thermoforming process, while toy bodies, bottles and pipes are made using blow molding process.
8. What is the maximum thickness that can be allowed for a plastics sheet in vacuum forming process?
a) 3 mm
b) 3.1 mm
c) 3.2 mm
d) 3.3 mm
View Answer
Explanation: Vacuum forming process is one of the important processes that are employed in thermoforming processes. The maximum thickness of the plastic sheet has to be noted, as a clamp is to be fitted around the plastic sheet. The maximum allowable thickness of this plastic sheet is 3.2mm.
9. The heater in vacuum forming process is heated up to 90°C.
a) True
b) False
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Explanation: In vacuum forming process, there is a clamp which has to be used for holding the plastic sheets. There is a heater employed for heating the mold cavity. The heater brings the polymer in a temperature range of 55°C to 90°C.
10. The initial cost in blow molding is low.
a) True
b) False
View Answer
Explanation: In blow molding, there is a mold cavity present inside the soft plastic, into which, the air with high amount of pressure has to be blown. The capital required for mold initially is quite less, making it a little inexpensive process.
Sanfoundry Global Education & Learning Series – Casting, Forming and Welding.
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