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The plastic injection moulding process is one of the most widely used and counts for a significant proportion of all plastic products. There are numerous processes of moulding plastic into parts, each method has its own advantages and requires specific knowledge and skill to perform.


The Injection Moulding Process Explained

There are six fundamental steps in the injection moulding process and these have been identified below:


Step 1 – Clamping:

There are three parts to an injection moulding machine; the mould, the clamping units which hold the two halves of the injection mould together during the process and the injection units.


Step 2 – Injection:

Plastic material in the form of granules are fed into the injection moulding machine through various conveying systems. The granules are heated at high temperatures until soft and melted.  The softened granules are then injected, under pressure via a runner system into the mould cavity and the mould cavity defines the shape of the part.


Step 3 – Dwelling:

At this point, there is a pause in the injection moulding process and to ensure the mould cavities are completely filled, pressure is applied.


Step 4 – Cooling:

The plastic moulding is then cooled and hardened in the mould.


Step 5 – Mould Opening:

Once the plastic has cooled down and hardened the injection mould clamping units open, separating the two halves of the mould.


Step 6 – Ejection

The ejection rod and plate then eject the moulded part and the whole injection moulding process then repeats.


The injection moulding process produces a vast number of high quality parts, very quickly with great accuracy and precision. Other advantages include, minimal wastage and a range of material options. Find out more about tooling for the injection moulding process.


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Looking for more information? Check out our blog, News & Views for useful articles, tips and tricks on plastic injection moulding.