Plastic injection moulding is one of the most widely used manufacturing processes worldwide. It’s superbly well-suited for the mass production of high-quality, low-cost plastic parts.

But how does plastic injection moulding work in practice? What steps are involved in bringing ideas to life?

Read on to find out.

Step 1: Clamping – Securing the Mould

The first step in the plastic injection moulding process is clamping. A clamping unit closes and holds the two halves of the mould tool tightly together, keeping it shut against the high pressures produced in the mould when plastic is injected.

This is essential to ensure the molten plastic is injected into a secure, closed environment, preventing any leaks or defects in the final product.

The clamping unit applies substantial pressure to keep the mould shut during the injection process.

Step 2: Injection – Filling the Mould with Molten Plastic

Once the mould is securely clamped, the injection phase begins.

Plastic granules are fed into a hopper above the moulding machine. As these move down from the hopper into the barrel below, rotating screw transfers the pellets to the forward heated part of the barrel.

A hydraulic ram injects the molten plastic into the mould tool under very high pressure, ensuring that it fills up the entirety of the cavity, creating a detailed and accurate representation of the desired part.

Step 3: Cooling – Allowing the Plastic to Set

After the molten plastic has been injected into the mould, it needs time to cool and solidify. The cooling stage allows the plastic to set into its final shape.

The cooling time can vary depending on factors such as the type of plastic used, the wall thickness of the moulded part, and the presence of cooling channels within the mould tool.

In many cases, the cooling phase is the most time-consuming step in the injection moulding process. Still, it’s essential to ensure the final product’s quality and structural integrity.

Step 4: Ejection – Removing the Moulded Part

Once the plastic has cooled and solidified, it’s time to remove the newly moulded part from the tool. This is known as the ejection step.

There are several methods for ejecting the part, including pins, blades, bars, sleeves, or lifters. The most common approach is to use ejector pins strategically placed within the mould tool to push the part out once it has cooled.

The ejection process must be carefully designed to remove the part without any damage or deformation.

Step 5: Inspection – Ensuring Quality Control

The final step in the plastic injection moulding process is inspection.

After the moulded part has been ejected, it undergoes a quality control check to ensure it meets the required specifications and standards.

Inspectors look for common defects such as warping, weld lines, sink marks, or flashing, indicating that the injection moulding machine settings needs to be fine-tuned to produce better-quality parts.

Some moulded components may also require additional trimming or assembly before they’re ready for use in their intended application.

Summing Up

Understanding the five key steps of plastic injection moulding – clamping, injection, cooling, ejection, and inspection – is essential for anyone involved in designing, developing, or producing plastic parts.

As a leading provider of plastic injection moulding services, BEC Group has mastered this art over decades.

We offer the expertise and state-of-the-art facilities to bring plastic injection moulding projects to life, from concept to completion.

Contact us today to learn more about how we can help you benefit from the power of plastic injection moulding for your next project.