 Basic concept diagram of gas-assisted injection molding | |
| Process type | Injection molding process |
|---|---|
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 process. In gas-assisted molding, the plastic material is injected into the mold cavities like the regular injection molding 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 part is ejected like the regular injection molding process.
Advantages
This process forms hollow parts that are cheaper than traditionally injection molded 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
- Greener
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
- Rotational molding (also produces hollow parts)
- Direct injection expanded foam molding
- Fusible core injection molding
- Metal injection molding
- Multi-material injection molding
- Reaction injection molding
References
- Seong-Yeol Han, Jin-Kwan Kwag, Cheol-Ju Kim, Tae-Won Park, Yeong-Deug Jeong. "A new process of gas-assisted injection molding for faster cooling". ScienceDirect.
{{cite web}}: CS1 maint: multiple names: authors list (link) - "Real-time diagnostics of gas/water assisted injection molding using integrated ultrasonic sensors". NRC Publications Archive, from National Research Council Canada. Retrieved November 9, 2020.
- "What is gas assisted injection moulding?". Dienamics. Retrieved November 9, 2020.
- "External Gas Molding Squeezes Out Sinks". Plastics Technology. Retrieved November 10, 2020.
- "New Methods Expand Roles of Gas-Assist Molding". Plastics Technology. Retrieved November 9, 2020.