Moulding Processes

Plastic Processes

- Injection moulding uses granulated plastic

- Granulated plastics heat quicker
- The mould is the most important part of manufacturing

Injection Moulding

- No waste material

- Lots of detail to the finished product (e.g Bottle lids)
- Quick Process
- Quiet
- Granulated Plastics (Thermoplastics)

The stages of injection moulding:

1. Granulated plastic is fed from the hopper into the injection moulding machine
2. It is then fed onto the rotating screw (Archemidial Screw), the screw carries the plastic along the barrel to the mould. Heaters surround the barrel so it melts the plastic as it travels along the screw.
3. Once the melted plastic has reached the end the screw pushes the melted plastic into the mould
4. It is then left to cool, and is then removed from the mould.

Compression Moulding

- Tolerance
- Hydraulic Press

- Powdered plastic

- Used to make anything with a slight indentation in

The stages of compression moulding

1. The mould is heated
2. The piece of plastic is placed into the mould as it heats up
3. The hydraulic press begins to move down once the plastic has reached the correct temperature
4. As the upper and lower mould meet, the plastic is compressed into the shape of the mould
5. The upper mould is then removed and the plastic is left to cool

Rotational Moulding

Stages of rotational moulding:

1. The hollow mould is filled with powdered plastic which has to be weighed correctly to avoid the product being too thick
2. The mould is then closed and begins to be heated up
3. Once the mould is heated fully it begins to rotate
4. Whilst rotating centrifugal force means that the plastic forms a layer around the edge of the mould
5. This is then cooled and removed from the mould to form a hollow shape.