Pros And Cons Of Gas Assisted Injection Moulding


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What is Gas-assisted injection moulding? What are the pros and cons of gas-assisted injection moulding? Do you know the involved in Gas-assisted injection moulding? This article will explain in details all you need to know about Gas-assisted injection moulding.

a diagram showing the processes involved in gas-assisted injection moulding

Gas-assisted injection moulding is a manufacturing process used primarily in the plastic industry. Gas-assisted injection moulding, or GAIM as it’s more commonly referred to, operates on the same basic principle as conventional injection moulding.

However, instead of using air pressure to force molten plastics into a mold cavity, GAIM uses a mix of compressed air and nitrogen gas (or an inert gas like argon) that is injected directly into the molten plastics to create enough pressure for them to be forced through the nozzle.

The main benefits of this process are increased production rates and material properties that are enhanced by better heat transfer from the nozzle into the extruded material.

What Is Gas Assisted Injection Moulding?

Gas-assisted injection moulding is a manufacturing process that uses compressed air and an inert gas to mold plastic parts. Gas-assisted injection moulding takes place inside high pressure, large capacity machines that can fill and handle the enhanced pressures of GAIM.

In conventional injection moulding, air pressure is used to force molten plastics into a mold cavity. This same principle can be applied in GAIM.

In GAIM, a process called homogenizing air works in conjunction with a special nozzle to blow or “homogenize” a mixture of heated air and nitrogen into the molten plastic that is to be injected into the mold.

The pressure of homogenized air forces the plastic into the mold cavity. The turbulently stirred plastic then cools rapidly in the eventide through an internal cooling jacket.

The best material for GAIM is polystyrene (PS) because it has very low shrinkage, excellent dimensional stability and it can be shaped with no solvent. Other materials would work but they would need to be softened by additional additives to reduce their higher resistance to heat transfer (shrinkage).

Gas-assisted injection moulding is a highly technical form of injection moulding, that uses both plastic and gas (usually nitrogen) to fill an injection mould under pressure. It is a specific type of injection moulding that is a popular choice for manufacturing high-performance plastic parts.

Gas-assisted injection moulding can produce parts at a much higher speed than traditional injection moulding. The process also allows for the creation of plastic parts that have better pressure resistance, as well as improved heat transfer in comparison to conventional processes.

Gas-assisted injection moulding, while it has been in use since the 1960’s, is still best suited to the manufacturing of small to large quantities of a specific plastic part. This is because it is not as economical as traditional methods. It requires heavier machinery and more time-consuming setup operations.

The filling time of a Gas-assisted injection moulding machine can be around 10 times faster than that of a conventional injection moulding machine. And by performing this task so quickly, the cooling time is also shortened exponentially.

This is a major benefit for manufacturers, as pipes and equipment can be kept hot for a longer period of time. This makes them more efficient.

A further benefit is that Gas-assisted injection moulding allows for the creation of parts that are stronger and more resistant to damage than conventional methods. The parts tend to have improved dimensional stability, thus allowing for greater tolerance to various weather conditions, as well as superior heat transfer characteristics.

The main drawback of Gas-assisted injection moulding is that it is an extremely expensive process to set up and operate. It requires specialized machinery and tools, so it can be considered an investment on behalf of the manufacturer.

a diagram showing the inflow and outflow of gas in a gas-assisted injection moulding

Process Involved In Gas Assisted Injection Moulding

Gas-assisted injection moulding works by injecting pressurised nitrogen gas into the interior of a mould, forcing the molten plastic material against the outer surfaces of the mould. The heat of the molten material is then transferred to the mould, allowing it to cool and solidify without shrinking.

Conventional injection moulding uses air pressure to inject the molten plastic material into a mould. In gas-assisted injection moulding, compressed air is combined with nitrogen gas and injected at high pressure into a pressurized vat. The mixture of gases inflates the vat like a balloon.

Molten plastic is injected into this pressurized vat in high volumes and at high speeds, which then forces it out of an ejector nozzle that sits inside of the vat. The outside of the nozzle is cooled as it exits the vat by ambient air, but the inside of the nozzle is still at a high temperature.

As this air cools, it creates a vacuum, which pulls the plastic inwards towards the hot area inside of the nozzle.

The plastic then gets forced through an injection tip and is directly injected into a cavity that sits in many injection moulding machines, forming the finished part.

Moving forward, now that we have had a well detailed understanding of what gas-assisted injection moulding is and the processes involved in gas-assisted injection moulding, let’s move on to the next topic which states the advantages and disadvantages of gas-assisted injection moulding.

Pros And Cons Of Gas-Assisted Injection Moulding

Here, we will be looking into the pros and cons of gas-assisted injection moulding but firstly, we will take a look at the pros of gas-assisted injection moulding and then later the cons.

Pros Of Gas-Assisted Injection Moulding

Some of the advantages of gas-assisted injection moulding are as follows:

1. Environmentally Friendly

Gas-assisted injection moulding is a lot more environmentally friendly than some other molding methods, specifically water-assisted injection moulding and slush moulding. It reduces the energy used in the production process by switching from hot water to cold nitrogen, which cuts down on the amount of heat that is produced.

That would then help to reduce the heat that is generated during the cooling process. This has been a huge problem in industries around the world, and can be reduced with gas-assisted injection moulding.

It also helps to reduce the waste produced by cutting down on how much water that is needed in the production process. In addition to this, it also reduces waste by using a more effective cooling mechanism than standard technology does.

2. Increase In Dimensional Stability

The dimensional stability of the final part produced has been greatly improved by the use of gas-assisted injection moulding. The design and shape of the finished product is better because these parts have fewer shrinkage issues, which means that making these parts is more accurate.

And in some cases, the production cost can be reduced because of this. The better finish effect also improves productivity by improving the surface finish on the finished part. This will then allow for less time spent on production and make a great difference for manufacturers around the world.

3. Reduces Warpage And Shrinkage

The use of gas-assisted injection moulding can reduce warping and shrinkage that is common in some cases. This is because of the way that the molten plastic flows through the nozzle – instead of being forced into a mould, it flows into the cavity and stays in place.

These parts are also more resistant to shrinkage as they have a lower tendency to change dimensions throughout the cooling process. This helps to make them more accurate, give them better shape retention, as well as resisting warping.

Cons Of Gas-Assisted Injection Moulding

Some of the disadvantages of gas-assisted injection moulding are as follows:

1. Costly

The equipment and tools required for gas-assisted injection moulding cost a lot of money to purchase, set up and maintain. This is often an investment for the manufacturer and does not directly affect the end product.

This is only one concern though. The costs can increase even more by having to replace components that stop working or by replacing defective parts during production.

2. Requires High Level Of Expertise

The process of gas-assisted injection moulding is highly complex and requires a lot of skill and expertise to perform. This can make it difficult for anyone that wants to use this technology, specifically smaller manufacturers and new companies.

Because of the amount of skill required, it can be very specialized and not cost effective, so only larger companies are able to use gas-assisted injection moulding with ease.


Gas-assisted injection moulding is an economical and environment-friendly method of producing plastic parts in a very high rate. It also produces more accurate and stable parts, as well as reducing waste.

This technology can be highly specialized, requiring entry level or higher levels of skill to operate it. It is also very costly – you need a lot of capital to get started, but the bigger your company gets the higher it will set you back.

Nonetheless, gas-assisted injection moulding is a great option for companies that have the money and skills to set up the system. The technology is used in several industries and has helped many followers to improve their production processes.

It is used in various industries, such as the medical sector where it is used to make bone screws, and also in the automotive industry where gas-assisted injection moulding is used to make plastic parts for vehicles.

Gas-assisted injection molding is a great technology that has improved production facilities around the world. It is constantly being used and improved upon so that it can be more efficient and effective for users.

a diagram showing the movement and principles involved in gas-assisted injection moulding

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