POLYMERS

Thermoplastics

can be repeatedly softened by heating and hardened by cooling

• acrylic

• LDPE

• HDPE

• PET

• PVC

• uPVC

• PP

• ABS

Acrylic

• tough

• lightweight

• good chemcial resistance

• used for car lights, cnc laser cut items, lighting units, lighting covers and baths

LDPE

• very tough

• good chemical resistance

• weather proof

• low level of rigidity

• used for squeezy detergent bottles, toys, carrier bags, bin lines, general packaging, food wrap film, food trays

HDPE

• weatherproof

• tough

• good chemical resistance 

• used for chemical drums, toys, household and kitchenware, long life carrier bags, buckets, bowls

PET

• tough

• flexible

• hard

• lightweight

• used for packaging, clothes,drink bottles, food packaging, detergent bottles and shampoo bottles

PVC

• tough

• rigid

• good weather and chemical resistance

• flexible

• used for pipes, electrical insulation

uPVC

• rigid

• opaque

• tough

• hard

• good weather, chemical resistance 

• used for window frames, external doors, guttering and downpipes, water service pipes, bank cards

PP

• tough

• flexible

• good fatigure resistance 

• resistant to chemicals 

• used for food packaging, medical equipment, rope, folders

ABS

• tough

• hard

• good impact strength

• used for saftey helments, suitcases, computer housing, handles

Thermosetting

can only be heated and shaped once

• Epoxy resin

• UF

• Polyester resin

Epoxy resin

• tough

• rigid

• hard

• good chemical resistance 

• encapsulating electrical components, adhesives, surface coating, pacemakers, aerospace applications

UF

• good electrical insulation

• hard

• heat resistance

• resistant to deformation 

• used for electrical casings, sockets, switches 

Polyester resin

• resistant to water, heat, and chemicals 

• ridid

• brittle

• used for bath tubs, boat hulls, chair seats, boat hulls

Vaccum Forming Method 

• materials used: HIPS, Polyester, ABS, Acrylic

• used for plastic yogurt, pots, bath tubs

1. the mould is created from mdf/plywood

2. The mould is placed into vacuum former

3. plastic sheet placed into vacuum former and heated until pliable 

4. mould is raised up into the sheet and air is removed to seal it

5. plastic takes shape of mould and allowed to cool

6. remove mould once cooled

Injection Moulding Method 

• Materials - ABS, Acrylic, PVC

1. Beads, pellets, granites are placed into hopper

2. they are fed through and archimedes screw drag granules through melting it

3. once pass through heater and become liquid, hydraulic piston forces it into mould

4. plastic cools and takes shape of mould

5. removes mould using ejector pins

Blow Moulding method

• Materials - HDPE, PP, LDPE, PET

• water bottles, toys, bins

1. plastic is heated and extruded to create a piston 

2. piston is placed in the mould, which closes on it and pinches the end of plastic 

3. heated compressed air is blown into piston

4. plastic fills in the mould with hollow interior

5. plastic is cooled using water

6. once cooled, remove mould and trim excess plastic

Rotational moulding method

• Materials - HDPE, PP

1. plastic is weighed depending on desired thickness and put into mould

2. mould is placed on rig in huge oven and heated

3. as its heated it is rotated on 2 axes to allow polymer coat evenly

4. once desired thickness reached mould is cooled

5. remove from mould

Line Bending method 

• materials - Acrylic 

1. mark out line that requires bending 

2. preheat the strip heater to right temperature 

3. add the plastics in heater on marked out line 

4. once heated bend plastic to desired angle 

Elastomer

• materials which at room temp can be deformed under pressure and then upon release of the pressure return to their original shape

Natural rubber

• high tensile strength 

• low elongation 

• good hardness

• tough

• electrical insulator 

• good cold resistance 

• used for automotive industry, tires, tubes, hoses, gaskets, belts, balloons, toys, footwear

Neoprene

• good thermal resistance

• toughness 

• good oil and chemical resistance 

• excellent weather resistance 

• good abrasion resistance 

• electrical insulator 

• used wet suits, laptop cases, industiral wire insulation, automotive applications

Polymers

• made via fractional distillation of crude oil

• takes hundreds of years to degrade

• polymers are self finishing.

Resin casting method

1. Pour the polymer resin into a pre-made mould and then allow the resin to set into shape

2. The mould is then gently vibrated to expel any air bubbles from the casting 

3. this is done at room temperature, where the moulds are made using mdg 

• materials - acrylic, polyester, epoxy 

• products - toys, jewellery, prototype models, dentistry

Blow moulding process 

• used for drink bottles, shampoo, detergent

1. heated plastic is extruded into parison tube

2. mould closes, parison is gripped in place

3. compressed air blown into parison tube which inflates

4. parison fills

5. screw threat in the neck of the bottle is formed during the process

6. mould cools

7. product trimmed

Injection moulding

• used for electrical casings

1. thermoplastic granules are fed into a hopper

2. hopper feeds an archimedes screw that drags the granules past a heater where they are plasticized

3. when the soft, pliable plastic reaches the end of the screw a hydraulic piston forces it into the mould

Vacuum forming

• used for lightweight trays, box inserts and liners, takeaway coffee cups, yogurt pots

1. mould created out of mdf

2. mould Is placed into a vacuum former

3. plastic sheet placed into vacuum former and heated until bendable

4. mould is raised up to the sheet and air is removed to seal it

5. plastic takes shape of mould and allowed to cool

6. remove mould once cooled

Extrusion

• similar to injection moulding but the polymer is forced through a die at the end

• used for solid rods, angle section, curtain track
  

Rotational moulding method

• used for traffic cones, kayaks, water tankes, childrens play equiprment 

1. polymer granules or powder weighed depending on wall thinking and put into mould

2. mould placed on rig in a huge oven and heated

3. as it heats its rotated slowly in two axes allowing the polymer to coat the inside of the mould evenly

4. once desired thickness reached mould is cooled

Blow moulding features

• for making hollow thin walled components

• high inital tooling cost

• used for continous production

Injection moulding features

• complex 3D shapes made quickly, easily

• fast industrial production method

• high inital tooling cost

• used for large scale mass or continous

Rotational moulding features

• produces seamless hollow components with large wall thickness

• used in large-scale batch or mass production