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Injection Moulding Process

    • Clamp the mould tool in the press, between the moveable platern and stationary platern.
    • Ensure that the tool is suitably lubricated to function.
    • Mix the thermoplastic material with masterbatch in the hopper to achieve the required colour (If the material is compounded to the finished colour this is not necessary).
    • Set the guide process parameters including temperature control.
Injection moulding process
    • The material funnels down into the screw due to gravity from the hopper onto a turning screw inside the barrel.
    • The barrel is heated at staged temperatures along its length to allow the material to solidify and to move along the screw.
    • The screw rotates which moves the material forward with the pressure and speed, forcing the plastic through the gate into the mould tool cavity which forms the shape of the finished product.
    • The mould tool is held at a constant temperature to draw out the heat from the product after injection, so, the material sets off to a solid form.
  • After a predetermined cooling time the mould tool opens, with the product held in the ejection half of the tool.
  • The automatic ejection system then moves forward to release the product from the mould tool into a collection box. The unused spru and runner can be recycled for use again.
  • After we get the manufactured piece, the mould tool is closed and clamped and the process begins again.

The method of plastic injection moulding begins with using a raw material polymer, such as Polystyrene, Polypropylene, ABS or Nylon. There are many more polymers but these are the most common. The polymer can be coloured by adding Master Batch to match any colour desired.

The machinery varies in size from very small machines with clamp forces from 1 tonne, this would be for very small injection mouldings weighing a few grams, up to machines with a clamp force of 3000 tonnes plus, for boats and other large injection mouldings.

This is a 600 tonne machine producing a chair shell. The mould inside the machine comprises of two halves, one half male and the other female. When the machine closes this enables molten plastic to inject into the mould and the cycle time also allows the moulding to cool. Inside the tool are water circuits to reduce the material temperature from about 200 degrees C to about 60 degrees C. When the mould opens the product is then ejected and a robot will then lift the moulding onto a conveyor belt.

Settings, temperatures and timings are very important factors in the process. BSA has an excellent quality control system, where production is checked every two hours.

The product can then be packed and despatched to the customer