Injection moulding is a critical method of manufacturing, one which has been in use for many years – with the first machines appearing in the 1930s, in fact!  The screw-drive method that is still in use today was developed in 1946 and which forms a critical component of the process. Plastic injection moulding can be used to produce items such as packaging, wire spools, automotive components, toys and so much more.


What is injection moulding?

Injection moulding is the process of heating raw material to its melting point before forcing the material into a mould. Once in the mould, the material is allowed to cool into a hardened shape. Modern injection moulding generally makes use of fully automated, closed-loop, microprocessor-controlled machines.

Injection moulded products can be used for virtually every product and industry.

A brief overview of the injection moulding process

There are a number of steps involved in the process, however here is a brief overview of the general steps:

  1. The part is designed, and prototypes made and tested
  2. A durable aluminium or steel mould is designed and build.
  3. The raw material is fed into the hopper
  4. The mould closes and is held shut by hydraulics to withstand the pressure of the incoming material.
  5. The material is fed into a heated barrel, where it becomes viscous.
  6. The heated plastic is injected into the mould
  7. The part is allowed to cool in the mould for a predetermined amount of time
  8. The part is ejected
  9. Quality assurance checks are performed on the part
  10. In the meantime, the mould is closed again for the next processing cycle.

The materials

Plastic injection moulding can be implemented with a large number of plastic resin types. Each resin has its own characteristics and benefits. Polyethene, polycarbonate, polyamide and polypropylene are some of the plastic types commonly used during the injection moulding process.

The advantages of Injection Moulding:

  • High-output production
  • Injection moulding produces low scrap rates
  • Low labour costs
  • Design flexibility
  • Can be used to produce very small parts
  • Good colour control
  • Complex part design
  • Reduced requirements for finishing
  • Multiple materials can be used at the same time
  • Good dimensional control

The disadvantages of Injection moulding:

  • High initial tooling and machinery cost
  • Small runs can be expensive
  • Part design restrictions


Plastic & Chemical Trading is a valuable technical partner that supports your manufacturing needs. Contact us today to ask how we can streamline and improve your business!