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M1# - Manufacturing of a Plastic Injection Mould

Project No.: M17

Project Title: Manufacturing of a Plastic Injection Mould


Plastic injection moulding is a manufacturing process in which molten plastics are injected into a steel mould with a hollow cavity at high pressure. The plastics fill up the cavity and solidify after cooling. A moulded plastic part is then ejected from the mould after mould open. This is a mass production process in which plastic parts are made in low cost and high speed.

The steel mould is vital in this process; therefore mould making is a very challenging job and is hi-tech.


Generally, a plastic mould consists of the following parts:

  1. Mould base
    The mould base is a standard part purchased from the mould base suppliers. It holds all the other mould components together. Trainees are required to open up pockets for the mould inserts by CNC machining.
  2. Cavity and Core inserts
    The core and cavity are the main part of the mould. The trainees are required to decide the parting line of the product and machine the mould cavities into these two steel blocks. Trainees are required to used different machining methods that they had learnt in the training to produce the parts. It includes, basic machining, EDM, wire-cut, CNC machining, High speed machining, hand fitting and mould polishing.
  3. Cooling system
    Trainees are required to design and make a suitable cooling system to cool down the mould during moulding.
  4. Running and gate system
    Suitable runner and gate system is required to feed the plastic material into the mould. Trainees can make use of the flow simulation software to facilitate the design of the gate location.
  5. Ejection system
    Trainees are required to design and make a suitable ejection system to remove the molded parts from the mould.
  6. Testing
    The mould produced will be trail run in an injection-moulding machine in the Plastic workshop. It is required to complete 10 good shots from the moulds, otherwise, modifications will be required until a satisfactory result is obtained.


In this project, the trainees are required to design and manufacture a plastic mould for a new product. The design must bear the identity of the PolyU. The size of the product should not larger than 150 mm x 150 mm and should be within the capacity of the injection moulding machine.


Trainees are required to:

  • Design and manufacture the plastic mould based on the given outline and specifications;
  • Schedule the manufacturing processes;
  • Prepare a bill of materials and a budget estimation for the whole project; and
  • Conduct commissioning and testing.

Upon completion of the project, a group presentation and a group report are also required.