This blog outlines the process of Injection Moulding, but if you are doing your research you will come across the flowing processes too:

• Rotational Moulding
• Extrusions
• Blow Moulding
• Thermoforming
• Compression Moulding

Each process differs greatly and your individual needs will determine what is right for you. If you’re unsure get in touch, we can assist to help you achieve your individual needs.


Injection Moulding is suited for high volume production runs, a variety of complexities and sizes, consistency, high durability, high quality, thin walled products and low cost per unit. The process requires extreme precision to ensure products can be mass produced, with almost perfect accuracy. To achieve this level of precision, you should invest in quality moulds. You can expect the average price of a mould to be approximately $20,000 however, it is similar to asking how much is a car. The greater the complexity, the greater the cost and a necessary investment for serious businesses.


Injection Moulding Process:
  1. Raw material is feed into a hopper and drawn into the barrel of the injection unit using the barrel auger screw.
  2. Inside the barrel, the screw moves the raw material forward. While moving, the material is gradually melted and entirely molten by the time it reaches the front of the barrel/nozzle.
  3. Once enough molten plastic is in front of the screw, the screw stops and injects forward like a syringe in a matter of seconds.
  4. The molten plastic is injected into the empty part of the mould/cavity, filling every recess and creating the product.
  5. While the product now cools and solidifies thanks to cold water circulating within the tool. Simultaneously the injection barrel screw is reversing, ready for the next cycle.
  6. Next the mould opens and the solid product is ejected. At this point, sometimes robots are used to remove the product or insert a static in mould labels (IML). You can find out more about the IML process via Logan Print –
  7. Finally, the empty mould closes and the injection cycle repeats.
In summary, the machine has THREE parts:
  1. Injection unit/screw barrel
  2. Mould
  3. Clamp/press
With THREE key parts to the process:
  1. Melt the raw material
  2. Inject raw material into clamped mould
  3. Cool down and eject the finished part


There are many advantages to Injection Moulding such as speed, efficiency and quality. Injection Moulders can run large quantities and quickly multiple pieces being made at the same time. The most important aspects to the Injection Moulding process are the temperature, pressure and speed. If not set correctly, each aspect has the ability to create large problems while the machine is running.  All raw materials have different melting points so the machines temperature must be adjusted accordingly. In regards to pressure, if there is too much, extra material will be forced out causing flashing/ugly part lines. Equally as important, if there is too little pressure, the product will be incomplete or short filled. Finally, if the speed is incorrect, the most burning or deformities from inconsistent flow rates are common consequences.


Further issues that may arise are:

• Streaks caused by moisture in the raw material.
• Seams/breakpoints where the molten material freezes off as it comes together.
• Burn marks on the product because of air trapped in the mould or too much heat in the barrel.

Injection Moulding is responsible for many, many everyday products. Look around you right now, there is a high chance you are surrounded by them. Not sure if you can see one? If you are reading this blog on a desktop or laptop, you’re staring straight at one – the cases of these products are Injection Moulded!


Other common Injection Moulded items:

• Plastic bowls, plates, cups, cutlery
• Bottle caps/closures
• Car parts
• Storage containers/crates
• Toys
• Chairs & tables


In summary, Injection Moulded products are an integral part of our lives! If you have any questions, please get in touch with the Waipak Team today


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