Gas Assist Molding Process

Gas assist is a process used in injection molding whereby a nitrogen bubble is injected into the melt stream to core out the part and leave a hollow tube-like cross section.

cross section showing hollow

Benefits Include:
Strength - Increased strength and rigidity through the creation of tubular structures in the part geometry.

Weight Reduction - Thick sections can be cored out with gas to reduce weight.

Design Flexibility - Ability to add thick sections as required and core them using gas assist technology.

Surface Finish - Better surface finish than structural foam . . . more like standard injection molding.

gas assist diagram

gas assist component

gas assist component

Materials Used in Gas Assist Molding

As with structural foam, most any thermoplastic material can be used in a gas assist application including:
• Polycarbonate
• Polyphenylene Oxide - PPO (Noryl)
• Polybutylene terephthalate - PBT (Valox)
• Acrylonitrile Butadiene Styrene – ABS
• High Impact Polystyrene - HIPS
• Polypropylene
• High Density Polyethylene - HDPE

Materials Benefits

• Thermoplastic materials can be recycled. At the molding stage the material can be ground to a small particle size and added in limited portions to virgin resin for molding use.
• Thermoplastic materials can also be ground and used for other post processing applications.
• Post molding finishing such as painting, shielding, decorating impacts the ease of recycling.
• Most common thermoplastics used today are RoHS compliant. Many of these are sold in a global market and are used in consumer products.

Gas Assist Design Considerations

• Gas entry and exit locations: The layout of the gas channels relative to the sprue or gates and flow of the material is critical to the success of the process.
• Typical geometries
• Avoid sharp corners

Avoid sharp corners

Typical Geometries

injection molding press

injection molding press

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