15. Polymer processes

Question 1

What are the polymer processes?

Answer 1

• vacuum forming
• thermoforming
• calendering
• line bending
• lamination
• injection moulding
• blow moulding
• rotational moulding
• extrusion
• compression moulding

Question 2

What is the polymer stock form used for vacuum forming?

Answer 2

thermoplastic sheet up to about 6mm thickness

Question 3

What are the key features of vacuum forming?

Answer 3

• moulds relatively easy to make
• moulds need a draft angle, air holes and rounded corners
• not cost effective for one off manufacture
• small scale batch and mass production

Question 4

What products are made by vacuum forming?

Answer 4

• lightweight trays
• box inserts and liners
• takeaway coffee cups
• yoghurt pots

Question 5

Draw the process diagram for vacuum forming, with labels.

Answer 5

See in person flashcards with pics on.

Question 6

What is the polymer stock form used for thermoforming?

Answer 6

thermoplastic sheet about 6mm thickness

Question 7

What are the key features of thermoforming?

Answer 7

• like vacuum forming, but additional mould is pressed onto the surface of the polymer sheet at the same time as the vacuum is applied
• good for fine detail such as moulding in logos
• slow process
• used in industrial production

Question 8

What products are made by thermoforming?

Answer 8

• bath
• food packaging (fruit punnets, cake boxes, sandwich boxes)

Question 9

Draw the process diagram for thermoforming, with labels.

Answer 9

See in person flashcards with pics on.

Question 10

What is the polymer stock form used for calendering?

Answer 10

thermoplastic pellets

Question 11

What are the key features of calendering?

Answer 11

• heated rollers squash and stretch the polymer to make it thinner
• industrial production method, carried out by specialist manufacturers
• used for continuous production

Question 12

What products are made by calendering?

Answer 12

thin polymer sheet and film

Question 13

Draw the process diagram for calendering, with labels.

Answer 13

See in person flashcards with pics on.

Question 14

What is the polymer stock form used for line bending?

Answer 14

thermoplastic sheet

Question 15

What are the key features of line bending?

Answer 15

• uses an electrically heated element that provides heat along a line
• quite slow and labour intensive
• used in school or college workshops
• suitable for one-off or limited batch production

Question 16

What products are made by line bending?

Answer 16

acrylic boxes, shelves or point-of-sale displays

Question 17

Draw the process diagram for line bending, with labels.

Answer 17

See in person flashcards with pics on.

Question 18

What is the polymer stock form used for lamination?

Answer 18

fibre based composite sheets (GRP, CFRP)

Question 19

What are the key features of lamination?

Answer 19

• requires a former to mould around
• polyester resin used as the polymer
• top gelcoat is applied which may contain pigment
• CFRP requires an autoclave for the product to cure

Question 20

What products are made by lamination?

Answer 20

• boat hulls
• kayaks
• train carriages
• theatre and film props
• theme park rides

Question 21

Draw the process diagram for lamination, with labels.

Answer 21

See in person flashcards with pics on.

Question 22

What is the polymer stock form used for injection moulding?

Answer 22

thermoplastic granules

Question 23

What are the key features of injection moulding?

Answer 23

• complex 3D shapes can easily be made
• fast industrial production method
• high initial tooling cost
• used for large scale mass or continuous production

Question 24

What products are made by injection moulding?

Answer 24

electrical product casings (computers, TVs, vacuum cleaners, calculators)

Question 25

Draw the process diagram for injection moulding, with labels.

Answer 25

See in person flashcards with pics on.

Question 26

What is the polymer stock form used for blow moulding?

Answer 26

thermoplastic tube 'parison'

Question 27

What are the key features of blow moulding?

Answer 27

- produce hollow thin walled components - high initial tooling cost - used for continuous production

Question 28

What products are made by blow moulding?

Answer 28

- drinks bottles - shampoo bottles - detergent bottles, etc

Question 29

Draw the process diagram for blow moulding, with labels.

Answer 29

See in person flashcards with pics on.

Question 30

What is the polymer stock form used for rotational moulding?

Answer 30

thermoplastic powder or granules

Question 31

What are the key features of rotational moulding?

Answer 31

- seamless hollow components with a large wall thickness - mould continuously rotated through heating and cooling - large scale batch or mass production

Question 32

What products are made by rotational moulding?

Answer 32

- traffic cones - kayaks - water tanks - kerosene tanks - children's play equipment

Question 33

Draw the process diagram for rotational moulding, with labels.

Answer 33

See in person flashcards with pics on.

Question 34

What is the polymer stock form used for extrusion?

Answer 34

thermoplastic granules

Question 35

What are the key features of extrusion?

Answer 35

- like injection moulding, except polymer is forced through a die - industrial production method - continuous production

Question 36

What products are made by extrusion?

Answer 36

- solid rods - tubing - angle sections - curtain track

Question 37

Draw the process diagram for extrusion, with labels.

Answer 37

See in person flashcards with pics on.

Question 38

What is the polymer stock form used for compression moulding?

Answer 38

thermoset polymer charge 'slug'

Question 39

What are the key features of compression moulding?

Answer 39

- uses a pre-weighed 'slug' of polymer - polymer removed from moulds while still warm - large scale batch production

Question 40

What products are made by compression moulding?

Answer 40

- electrical light fittings - switches - plugs - picnic plates and cups