Moulding Process'

Question 1

Positives and negatives of injection moulding

Answer 1

+complex shapes made fast and accurately

• high set up cost
• only solid shapes can be made

Question 2

What is compression moulding used for?

How does it work?

Answer 2

Main way of forming thermosetting polymers

Placed in mould, heated, former compresses with 5 tonnes

Question 3

Steps of line bending

2

Answer 3

1. lay sheet of acrylic over the heating element at the point you want the plastic to bend
2. Wait until hot then bend over a mould or jig

Question 4

Steps of vacuum forming

4

Answer 4

A piece of thermoplastic like polystyrene is heated about a mdf mould
Once heated the wooden mould is moved to the level of the plastic
The air is sucked out so the plastic takes the shape of the mould
This sets its shape, it has to have a 5* draft angle.

Question 5

Steps of blow moulding

3

Answer 5

The machine used for injection moulding is used to push a plastic tube into the mould
Air is then blown into the plastic causing it the expand and take the shape of the mould
The mould is opened and the product is taken out
Has to have a big opening

Question 6

Steps of extrusion moulding

Answer 6

Plastic granules are poured into a hooper
The Archimedes screw rotates and therefore moves the granules over the heater
The plastic is molten and pushed though a die
This is an infinite process That can be cut to any length

Question 7

Steps of injection moulding

5

Answer 7

Plastic granular in a hooper along with any additives
The Archimedes screw revolves, moving the polymer past the heaters
At this stage the plastic is molten-200
Inject the polymer into a two part mould
Water cool the mould then opens, pushing out the product.