Injection Moulding

Question 1

What is injection moulding?

Answer 1

Materials such as polystyrene, nylon, polypropylene and polythene can be used in a process called injection moulding. These are thermoplastics - this means when they are heated and then pressured in a mould they can be formed into different shapes.
The DVD Storage unit seen opposite has been made in one piece using this process

Question 2

Can you explain the stages of injection moulding?

Answer 2

1. Granules of plastic powder (note the plastics listed above) are poured or fed into a hopper which stores it until it is needed.
2. A heater heats up the tube and when it reaches a high temperature a screw thread starts turning.
3. A motor turns a thread which pushes the granules along the heater section which melts then into a liquid. The liquid is forced into a mould where it cools into the shape (in this case a DVD storage unit).
4. The mould then opens and the unit is removed.