Polymers

Question 1

what are stock forms

Answer 1

standard sizes for a material, component or product

Question 2

examples of stock forms

Answer 2

• sheets (acrylic)
• granules (Polypropylene)

Question 3

how can polymers be fixed

Answer 3

with nuts,bolts, screws and rivets

Question 4

what is additive manufacturing

Answer 4

a method of shaping a form by building on top of a material

Question 5

what is subtractive manufacture

Answer 5

a method of shaping a form by the removal of a material

Question 6

what is a filament

Answer 6

a material in thread like form

Question 7

what do some polymer based fibres contain

Answer 7

different wood carbon and metal fibres

Question 8

what is a bespoke product

Answer 8

a one off product that matches the client requirements exactly

Question 9

what is a chinagraph pencil and what’s it used for

Answer 9

used to mark on the high gloss surface of acrylic
- if not available, an alcohol based permanent marker can also be used

Question 10

how can acrylic be cut

Answer 10

• coping saw
• hacksaw
• file

Question 11

what temperature does acrylic need to be heated to to be able to bend without cracking

Answer 11

150 - 170

Question 12

what is a vacuum former

Answer 12

a machine that heats a polymer so that it is malleable enough to be pulled over a former with a vacuum

Question 13

how does a vacuum former work (use HIPS in the example)

Answer 13

1. HIPS is heated
2. once hot, the solid former is pressed into the HIPS from a bed that can rise
3. the vacuum is turned on, removing all the air from around the former
4. the HIPS takes the form of the solid former

Question 14

what is talc

Answer 14

a clay mineral that can be dusted in the former so that it drops out of the mould with ease

Question 15

why should a former have a draft angle

Answer 15

so that it doesn’t fr stuck in the mould

Question 16

how else can polymers be shaped

Answer 16

• press moulding
• drape formung

Question 17

how does injection moulding work

Answer 17

1. granular plastic is held in a hopper
2. it’s moved via an Archimedean screw, along a heated tube called the heating chamber
3. once the polymer has been melted, it’s pushed into a mould with a hydraulic ram
4. the mould is then cooled so that the moulded plastic can be removed

Question 18

why does the mould have a hydraulic ram in injection moulding

Answer 18

to make sure just enough material is injected into the mould each time

Question 19

how does extrusion work

Answer 19

• first two steps the same as injection moulding
• once the polymer has been melted, it is pushed through a die mould, which will form the shape of the extrusion
• because there is no hydraulic ram, molten plastic can be fed through the die continuously

Question 20

how to apply a finish on a polymer

Answer 20

• file can be used to remove some of it
• abrasive paper then used to remove file marks, known as “rubbing down”
• once the file marks are removed, a fine abrasive paper can be used to achieve a matt finish
• it an electric buffer or car body can give it a glossy finish

Question 21

how are polymers made

Answer 21

from crude oul

Question 22

what is a digital vernier calliper

Answer 22

a digital device for measuring accuracy