15 Polymer Processes

Question 1

Vacuum forming

Products
Key features - moulds, cost effectiveness, scale?
Stock form

Answer 1

Lightweight trays, box inserts, yogurt pots

Moulds east to make, but need draft angle, air hole, rounded corners
Not cost effective for 1 off
Good for small scale batch and mass

Uses sheets up to 6mm

Question 2

Thermoforming

What process is it like
1 Adv and dis

Answer 2

Baths, food packaging like sandwich boxes

Similar to vacuum, but used additional mould to press into surface of polymer sheet at the same time as the vacuum is applied
Adv. Good affine details eg logos
Dis, slow process, used for industrial production

Used sheets

Question 3

Calendering

Uses what kind of rollers
Who is it used by

Answer 3

Makes thin polymer sheet and film

Heated rollers squash and stretch the polymer to make it thinner
Industrial production method only done by specialists
Used in continuous production

Uses pellets

Question 4

Line bending

What does it use
Dis
Used in

Answer 4

Makes acrylic boxes, shelves, point of sales displays

Uses electrically heated line
Slow & labour intensive, used in schools
Good for one off or limited batch production

Uses sheets

Question 5

(Lay up) Lamination

What tools does it require
Stock form of polyester?
How is pigment applied
What extra thing does CFRP require

Layers (shown in diagram)

Answer 5

Make boat hulls, kayaks, train carriages, theme park rides

Requires former to mould
Polyester resin used
Top gelcoat applied may contain pigment
CFRP requires autoclave for the p. to cure

Used for fibe based composited cfrp GRP
Uses roller and mould. Layers are

Resin
Mat
Release agent
Mould

Resin and mat combine

Question 6

Injection moulding

Adv
Dis

Answer 6

Electrical product casings, tv vacuum, calculator etc

Complex 3d shapes made easily
Fast
High tool cost
Used for large scale mass or continuous

Uses granules

Diagram - hydraulic motor, feed hopper, heaters, Archimedean screw, mould clamp and moving mould, ejector pins, guide bar and hydraulic ram

Question 7

Blow moulding

What it produce
Dis

Answer 7

Makes drinks bottles, shampoo, detergent etc

Produces hollow thin wall p.
High tooling cost
Used for continuous

Uses tube parison

Diagram - extruder, mould halves, screw thread can be moulded, air blow through here

Question 8

Rotational moulding

Type of p. it makes
How is it heated

Answer 8

Traffic cones, kayaks, water tanks, toys and kids equipment

Makes seamless hollow component with large thick walls.
Mould continuously rotated through heating + cooling
Large scale batch or mass

Uses powder or granules

Question 9

Extrusion

Answer 9

Make solid rods, angle sections, curtain tracks

Basically injection, but polymer forced through die
Industrial production method
Continuous

Uses granules

Question 10

Compression moulding

What special type of plastic stock form used
What’s special about the moulds in this

Answer 10

Make electrical light fittings, switches, plugs

Uses pre-weighed slug
Polymer is removed from moulds when still warm
Large scale batch production

Uses THERMOSET polymer charge ‘slug’
Which is placed in lower mould
Both moulds/dies are heated
Hydraulic press pushes it to form around it