Gas-assisted injection molding
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Gas-assisted injection molding is a molding process where an inert gas is injected into the melted plastic pushing it further into the mold and resulting in hollow parts.


Basic concept

The basic concept of the gas-assisted molding process is quite similar to the regular
injection molding Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...
process. In gas-assisted molding, the plastic material is injected into the mold cavities like the regular
injection molding Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...
process but only up to 70%~80% of the mold volume. The melted plastic in contact with the mold walls begins to solidify, then nitrogen gas is injected into the mold through strategically designed and placed gas inlets, providing pressure that pushes the plastic into the mold extremities. The path of the bubble is controlled by taking the path of least resistance through the hottest, least viscous plastic, which keeps it centered from the colder walls of the mold. Finally the
molded Molding (American English) or moulding (British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have ...
part is ejected like the regular injection molding process.


Advantages

This process forms hollow parts that are cheaper than traditionally
injection molded Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...
equivalents. Molded parts also cool faster in this process. There is also usually less shrinkage as the thicker wall sections are hollow. Some of the benefits of this process are: *Thicker parts *Low clamp force *Lightweight products *Reduced part deformation (warpage) *Minimal residual stresses *No sink marks *
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Disadvantages

This molding technique is very difficult to apply to multi-cavity molds, especially if the cavity sizes are dissimilar. Clear or transparent plastic materials are an inappropriate option for this technique as the cosmetic-appearance can deteriorate.


See also

* Molding (process) * Rotational molding *
Direct injection expanded foam molding Direct injection expanded foam molding (also known as ''injection molded foam'') is a manufacturing process that creates soft foam products direct from a compound into a final product. This process eliminates the steps normally required for die ...
* Fusible core injection molding * Metal injection molding *
Multi-material injection molding Multi-material injection molding (MMM) is the process of molding two or more different materials into one plastic part at one time. As is the case in traditional injection molding, multi material injection molding uses materials that are at or ...
* Reaction injection molding


References

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External links


Plastic Injection Mold Design & Manufacturing
Injection molding