5. Plastics Flashcards

Question

List the three steps in injection ion moulding

Answer 1

1. Plastic powder is fed into hopper 2. A motor turns a thread which pushes the granules along the heated section, melting it to a liquid. 3. Liquid is forced into a mould where it cools into the shape.

Answer 2

``` Complex shapes Accuracy Mass manufacture - fast production rates Texture can be applied High quality surface finish - no further finish required Fine detail - integral parts Material flexibility Low waste ```

Answer 3

``` Sprue Marks Draw Angles Mould Split Lines Ejection Pin Marks Webs for Strength ```

Answer 4

1. A motor turns a thread which feeds granules of plastic through a heater. 2. The granules melt into a liquid which is forced through a die, forming a long 'tube like' shape. 3. The extrusion is then cooled and forms a solid shape.

Answer 5

``` Uniform cross section Availability in length repeatability Accuracy High quality surface finish ```

Answer 6

Smooth Walled Long Sections Uniform Thickness and Shape Line Texturisation

Answer 7

1. Plastic sheet is placed above the mould and clamped securely 2. Electric heater switched on to heat up plastic sheet until it becomes flexible 3. Shelf is raised and vacuum is switched on so air is removed from area below the plastic to wrap around the mould 4. Vacuum is turned off, shelf lowered and the product will then be ready for trimming

Answer 8

Economies of scale- large numbers can be produced Low cost- thin large sheets of plastic, large quantities Low quality design for throw away products

Answer 9

Material is usually thin Patterns/texture are transferred from mould Tapers are pronounced/obvious Thinning on sides

Answer 10

Polypropylene High density polythene Polystyrene

Answer 11

Polypropylene High density polythene PVC

Answer 12

High density polythene

Answer 13

1. A piece of plastic is placed in the mould and heated up until soft and malleable 2. The hydraulic press moves down and the plastic is compressed into the shape of the mould

Answer 14

Melamine formaldehyde | Urea formaldehyde

Answer 15

``` Products withstand heat/electrical damage High volume produced Complex shapes Little material waste Accuracy Repeatability Thermosetting plastics only quality surface finish/detail ```

Answer 16

Walls have uniform thickness (usually 3-6mm) | Quality surface finish

Answer 17

1. The plastic is heated until soft and malleable and put into the mould. The plastic is placed around the mould at the top. 2. The plastic is then blown I not the shape using compressed air. 3. Plastic cools on contact with mould surface. The mould is reopened and shape ejected.

Answer 18

Low density polythene

Answer 19

``` Accuracy Repeatability Smooth Surface Finish Hollow Products (with hole) One piece construction- don't have to join parts together ```

Answer 20

Hollow product with an opening at the top Mould separation lines almost any type of bottle Uniform wall thickness Webs for strength

Answer 21

1. Mould is filled with plastic powder and heated 2. The mould is rotated allowing plastic to be distributed over the hot mould surface 3. Mould surface is cooled and plastic retains the shape of the mould. Product is removed.

Answer 22

Polypropylene | Polystyrene

Answer 23

``` Symmetrical designs can be formed Complex one piece mouldings Tough rigid shapes Lightweight products Quality assured- repeatability No weak areas due to consistent thickness Good quality surface finish/ texture Relatively cost effective- hollow therefore less material used ```

Answer 24

Excellent surface detail No sharp concave sections/corners Uniform wall thickness Hollow products (with no opening)

Answer 25

Prototypes out of plastic.

Answer 26

They are made using CAD software and then printed

Answer 27

Testing and advertising before mass manufacturing starts

Answer 28

Sheets | Tubes

Answer 29

Line bender

Answer 30

The plastic would be heated in an oven.

Answer 31

It can be used to cut or engrave sheets of plastic | You can use these [plastic pieces to create 3D or 2D shapes.