KS3 D&T Lesson Plastic products and manufacturing

Plastics are everywhere! Where have you found them today? 2

What are plastics are made from? Natural materials like cellulose, coal, crude oil, natural gas and salt. Plastics can also be made from renewable sources like corn, potatoes and sugar cane. 3

Plastics are Polymers 4 Polymers are very long molecules, made by joining many ‘building block’ molecules into a chain Different ‘building blocks’ create different chains – with different properties Polymers come in two forms, thermoplastics and thermosets 4

Thermoplastics 5 Thermoplastics soften when heated. All thermoplastics can be melted and reshaped many times. 5

Thermosets During moulding, thermoset molecules form a tightly woven 3D network. This means thermosets cannot be re-melted and changed in shape. 6

Types of Plastics 7 There are several hundred different Each has properties that make it suitable for specific uses. 7

High-Density Polyethylene HDPE For containers, toys, utensils, industrial wrapping film and gas pipes. 8

PET For bottles, textile fibres and film food packaging. 9

Polypropylene (PP) For transparent all-weather sheeting, electrical insulators, bathroom units and automotive parts. 10

Polystyrene – PS 11 For electrical appliances, insulation, cups and plates, and toys. 11

PVC For window frames, pipes, flooring, wallpaper, bottles, cling film, toys, guttering, cable insulation, credit cards, and medical products. 12

Low-Density Polyethylene (LDPE) For pallets, agricultural films, bags, toys, coatings, containers, pipes, wrappings. 13

ABS For general appliance mouldings. 14

How are Plastics formed? 15

Injection Blow Moulding Plastic granules are heated and then extruded into the first mould. This creates the ‘pre form’: a completed neck with a tube of thick plastic attached. This is moved into a second mould and air injected to ‘blow’ it into the shape of the final mould, to form the product. Link view icon with animation at http://www.bpf.co.uk/data/iframe/injectionBlowMoulding.html VIEW ONLINE 16

Extrusion Blow Moulding Plastic granules are heated and then extruded into a mould. When the plastic is the right length in the mould it is cut off and air injected to ‘blow’ it into the shape of the mould, to form the product. Link view online icon with animation at http://www.bpf.co.uk/data/iframe/extrusion-Blow-Moulding.html VIEW ONLINE 17

Extrusion Plastic granules are melted then injected at high pressure through a ‘die’ to make a continuous length of plastic with a constant cross section. This cross section is called the profile. No animation link on this slide 18

Injection Moulding 19 Plastic granules are melted then injected at high pressure into a hot mould to form the product. Link view online icon with animation at http://www.bpf.co.uk/data/iframe/injectionMouldingAnimation.html VIEW ONLINE 19

Thermoforming Plastic sheet is heated and formed using a press and / or vacuum to form the product. Link icon with animation at www.bpf.co.uk/data/iframe/Thermoforming_RPC_BPF.html VIEW ONLINE 20

Rotational Moulding Plastic granules are added to a heated mould which is then rotated to coat the inside and form a thick-walled, strong product. Link icon with animation at www.bpf.co.uk/data/content/images/1/1_rotational_moulding.swf VIEW ONLINE 21

ANSWERS 22 Builder Beams – Extrusion Bump’ems – Rotational moulding Easy Trays – Thermoforming Crystal Cashmere – Injection Blow Moulding One spoon at a time – Extrusion Blow Moulding Flatpack Friends – Injection Moulding 22