The casing for the games controller shown is to be manufactured in a large scale production run, using a thermoplastic material - Leaving Cert Engineering - Question a - 2014

Injection moulding involves the following steps:

1. Feeding: Plastic granules are fed from a hopper into a heated barrel.
2. Melting: The granules are heated until they become a molten plastic liquid.
3. Injection: A motor-driven screw injects the molten plastic into a split mould cavity under high pressure.
4. Cooling: The plastic cools and hardens within the mould.
5. Ejection: The mould is opened, and the finished product is ejected.

A diagram illustrating this process is shown below:

    +--------------------------+
    |       Split Mould        |
    |         Cavity          |
    +--------------------------+
            /
           / Injection
          /
         +-----------+ 
         |           |
         |  Hopper   | 
         |           |
         +-----------+ 

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Plasticisers are added to polymers to increase their flexibility. They work by weakening the intermolecular forces between polymer chains, allowing them to move more freely.

Stabilisers help maintain the integrity of polymers by preventing degradation caused by environmental factors such as heat and UV light. They enhance the longevity and durability of the material.

The addition of glass or carbon fibre significantly increases the strength of plastics. These materials reinforce the polymer matrix, resulting in stronger and more rigid composites.

Lamination involves layering materials together, enhancing strength and flexibility. High strength plastics can be produced through layers of polymer and resin, bonded under heat and pressure.

1. Thermosetting plastics provide excellent heat resistance, making them suitable for applications involving high temperatures, such as in electric kettles.
2. They maintain their rigidity and shape under stress, ensuring durability in use.

Condensation polymerisation involves the reaction of monomers that contain functional groups. As they bond to form a polymer, a small molecule, often water, is eliminated as a by-product. This process creates a structure with strong cross-links, increasing the polymer's strength and thermal stability. An example of a polymer formed this way is phenol formaldehyde.