1. Which of the following is not a type of overwrap?
a) Decorative wrap
b) Paper wrap
c) Stretch wrap
d) Shrink wrap
Discussion
Explanation: Stretch wrap is not a type of overwrap. An overwrap is also known as a polywrap. Shrink wrap is a polymer plastic film, which shrinks on the application of heat. Paper wrap, like Kraft paper is used to overwrap items in a package or to overwrap a package. Decorative packaging is the quaternary packaging, which aims to enhance the looks of the good.
2. In thermoforming, plastic sheets are heated to ________
a) Boiling point
b) Tg point
c) Sag point
d) Melting point
Discussion
Explanation: In thermoforming, plastic sheets are heated to Sag point. It is the temperature at which the plastic softens and extends under its own weight, i.e., when the plastic begins to sag.
3. From which of the following processes, canopies for racing vehicles are made?
a) Drape forming
b) Mechanical forming
c) Pressure forming
d) Free blowing
Discussion
Explanation: Canopies for racing vehicles are made from drape forming. Drape forming is the process by which the plastic sheet is heated, such that it can be bent and shaped into any form without using a vacuum.
4. SPPF in thermoforming stands for ____________
a) Soluble peer pressure forming
b) Soluble phase pressure forming
c) Solid peer pressure forming
d) Solid phase pressure forming
Discussion
Explanation: SPPF in thermoforming stands for solid phase pressure forming. The SPPF process is primarily used to thermoform PP, a crystalline polymer that is difficult to thermoform uniformly in melt phase machines due to the sharp decrease in melt strength (viscosity) at its melting point.
5. APET is stable till 230°C.
a) True
b) False
Discussion
Explanation: The given statement is false. CPET (Crystalline PET) is stable till 230°C. Whereas, APET (Amorphous PET) softens over 63°C. The CPET process is based on conventional reheat thermoforming where an extruded PET sheet containing nucleating agents to speed up and maximize crystallization is reheated to around 170°C where it softens. After this, it is transferred in a hot mold and held so the crystallinity develops. Then it is transferred to a second mould for cooling.
6. In drape forming technique _______ is used for forming.
a) Vacuum
b) High pressure
c) High Temperature
d) Low pressure
Discussion
Explanation: In drape forming technique vacuum is used for forming. In vacuum forming, vacuum is heated below the preheated plastic sheet to draw sheet into cold mold cavity. The steps include heating the plastic sheet, placing the softened sheet is placed over a concave activity. Vacuum draws the sheet into cold cavity. The final product is then cooled.
7.Which of the following material is not thermoformed?
a) HIPS & ABS
b) POM & Nylon
c) PVC
d) PMMA
Discussion
Explanation: Among the given options, POM & Nylon is not thermoformed. Whereas, HIPS- High Impact Polystyrene, ABS- Acrylonitrile Butadiene Styrene, PVC- Polyvinyl Chloride and PMMA- Poly(methyl methacrylate) are thermoformed.
8. Bath tubs are made by __________ technique.
a) Free forming
b) Pressure thermoforming
c) Match die thermoforming
d) Drape forming
Discussion
Explanation: Bath tubs are made by drape forming technique. Drape forming is the process by which the plastic sheet is heated, such that it can be bent and shaped into any form without using a vacuum.
9. Thermoforming can be generally classified as ________ and _______ thermoforming.
a) pressure, temperature
b) vacuum, pressure
c) Thick gauge, thin gauge
d) Temperature, vacuum
Discussion
Explanation: Thermoforming can be generally classified as Thick gauge and thin gauge thermoforming. Thick gauge thermoforming is a term used for making heavy duty parts, such as- plastic pallets, refrigerator liners, etc. Whereas, thin-gauge thermoforming is the term used to describe the manufacturing of lighter and smaller things, such as disposable cups, containers, trays, lids, and other products for the food, medical, and general retail industries.
10.Which of the following is not a mold used in thermoforming?
a) Aluminium mold
b) Steel mold
c) Wooden mold
d) Plastic mold
Discussion
Explanation: Steel mold is not used in thermoforming. The mould used in thermoforming should be such that the plastic polymer to be thermoformed isn’t affected by it. The mold used in thermoforming are- aluminium mold, plaster of paris mold, plastic mold and wooden mold.