The toy train shown below has been manufactured using a plastic called HDPE High Density Polyethylene. The coupling rod is of great importance as it is linked to both of the main wheels.

The manufacturing process is called injection moulding. In the space below draw a labelled sketch showing this process. Add explanatory notes.

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.
4. The liquid is forced into a mould where it cools into the shape (in this case a coupling).
5. The mould then opens and the coupling is removed.