polymer processes

Question 1

how many polymer processes are there

Answer 1

10

vacuum forming
calendaring
injection moulding
blow moulding
compression moulding
line bending
thermoforming
lamination/lay up
rotational moulding
extrusion

Question 2

vacuum forming process

Answer 2

1. thermoplastic placed between mould and heater
2. heater turned on, thermoplastic softens and platen is raised
3. thermoplastic moulds over the mould on the platen whilst air is being ‘vacuumed’ out
4. platen removed once polymer is cooled

Question 3

vacuum forming polymer stock form

Answer 3

usually HIPS, or other thermoplastic sheet 6mm thick

Question 4

vacuum formed products

Answer 4

lightweight trays
takeaway coffee cups
yoghurt pots
plastic packaging

Question 5

vacuum forming key features

Answer 5

• mould needs draft angle and air holes and rounded corners
• not cost effective for one off manufacture
• best for batch or mass production

Question 6

thermoforming process

Answer 6

1. thermoplastic heated and softened then placed between positive and negative mould
2. positive mould pressed into the surface of the polymer so that polymer fits into the negative mould
3. air is vacuumed out

Question 7

thermoforming polymer stock

Answer 7

thermoplastic sheet 6mm thick

Question 8

thermoforming products

Answer 8

bathtubs
cake / sandwich boxes

Question 9

thermoforming key features

Answer 9

good for fine detail like moulding in logos
slow process

Question 10

calendaring process

Answer 10

1. thermoplastic pellets feed through heated feed rollers
2. feed rollers squash and feed the polymer to make it thinner
3. polymer is also feed through tension feeders to ensure the polymer doesn’t sag
4. if required, polymer can be feed through embossing/cooling rollers for final details/textures

Question 11

calendaring polymer stock form

Answer 11

thermoplastic pellets

Question 12

calendaring products

Answer 12

thin polymer sheets ie cling film

Question 13

calendaring key features

Answer 13

continuous/ batch production

Question 14

line bending/ strip heating process

Answer 14

1.strip is heated
2. thermoplastic sheet placed over the heated strip and is softened
3. thermoplastic is then bent to desired shape maybe over a jig?

Question 15

line bending polymer stock form

Answer 15

thermoplastic sheet
usually acrylic

Question 16

line bending products

Answer 16

acrylic boxes, shelves, point of sale displays

Question 17

line bending key features

Answer 17

slow, labour intensive
one off or limited batch production

Question 18

lay up lamination process

Answer 18

1. release agent and resin added to the mould with the fibre based composite
2. roller rolls out the fibre based composite in the shape of the mould

Question 19

lay up lamination polymer stock form

Answer 19

fibre based composite sheets
GRP, CFRP

Question 20

lay up lamination products

Answer 20

boat hulls
film props
water park slides
theme park rides
train carriages

Question 21

injection moulding process

Answer 21

1. thermoplastic powder placed into hopper
2. the heater melts the powder
3. the Archimedean screw rotates pulling melted powder through the chamber
4. hydraulic motor pushes hot powder through the mould
5. moulded polymer cooled and and mould opens
6. ejection pins push product out
7. product is trimmed

Question 22

injection mould polymer stock form

Answer 22

thermoplastic granules or powder
maybe ABS, PMMA??

Question 23

injection mould products

Answer 23

electrical product casings eg
tvs, computers, vacuum cleaners?

Question 24

injection moulding key features

Answer 24

complex 3D shapes easily made
fast industrial production method
high initial cost
large mass or continuous production

Question 25

blow moulding process

Answer 25

1. parison (thermoplastic tube) is extruded between the two mould halves
2. hot air is blown into the parison as the mould close into each other
3. parison takes shape of the mould

Question 26

blow moulding polymer stock

Answer 26

thermoplastic tube (parison)
granules

Question 27

blow moulding products

Answer 27

drink bottles
shampoo bottles
watering cans
detergent bottles

Question 28

blow moulding key features

Answer 28

continuous/ mass production
high initial cost

Question 29

rotational moulding process

Answer 29

1. mould filled with thermoplastic powder/granules
2. mould is then heated in an oven and then rotated slowly so that plastic coats the insides of the mould
3. mould is then cooled and removed

Question 30

rotational moulding polymer stock form

Answer 30

thermoplastic granules/powder

Question 31

rotational moulding products

Answer 31

kayaks
traffic cones
children’s play equipment
water tanks
heavy duty hollow products

Question 32

rotational moulding key feature

Answer 32

mass/ batch production

Question 33

extrusion process

Answer 33

1. thermoplastic granules/powder placed into hopper
2. Archimedean screw rotates and pulls the heated thermoplastic granules through the chamber
3. hydraulic motor forces the melted granules through the steel die

Question 34

extrusion polymer stock form

Answer 34

thermoplastic granules and powder

Question 35

extrusion products

Answer 35

solid rods, tubing
curtain track

Question 36

extrusion key features

Answer 36

mass/ batch production
expensive initially

Question 37

compression moulding process

Answer 37

1. preheated thermoset slug placed between heated upper and lower mould
2. hydraulic press pushes heated upper mould into the slug to force the slug into the shape of the lower mould
3. product removed while still warm

Question 38

compression mould polymer stock form

Answer 38

thermoset slug

Question 39

compression moulding products

Answer 39

electrical light fittings
plugs
switches
picnic plates and cups

Question 40

compression moulding features

Answer 40

batch/mass production