Gas-Assist Injection Molding: Process, Benefits and Uses

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Gas-assist injection molding (GAIM) injects nitrogen gas into the melt during injection to create hollow sections and reduce sink marks.

How It Works:

1. Short shot of plastic is injected into the cavity
2. Nitrogen gas (usually 100-350 bar) is injected through gas pins
3. Gas pushes the melt forward, filling the cavity completely
4. Gas pressure is held during cooling to prevent sink marks
5. Gas is vented before mold opens

Key Benefits:

• 20-40% material savings on thick parts
• Eliminates sink marks without long cooling time
• Reduces clamp tonnage requirement by 30-50%
• Shorter cycle times (15-30% faster)
• Better surface quality - no witness lines on A-surface

Common Applications:

• Automotive: Door handles, mirror housings, dashboards
• Appliances: Vacuum cleaner handles, washing machine panels
• Consumer: Power tool housings, chair armrests

Design Guidelines:

• Wall thickness: 2-4mm for gas channel areas
• Gas channel should follow natural fiber flow path
• Gas pin location should be downstream of gate
• Use CAE simulation to predict gas penetration

GAIM is especially cost-effective when consolidating multi-part assemblies into single molded components.

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