Gas-assist injection molding (GAIM) uses pressurized nitrogen gas to hollow out thick sections of molded parts. This technique reduces weight, eliminates sink marks, and improves dimensional stability.

How it works:
1. Plastic is injected into the mold at 70-95 percent of full shot volume
2. Nitrogen gas at 100-300 bar is injected through nozzles or gas pins
3. Gas displaces the molten core, pushing plastic against cavity walls
4. Gas pressure is maintained during cooling to prevent shrinkage
5. Gas is vented before mold opens

When to use gas-assist:
- Parts with thick sections and thin walls transitioning
- Components requiring internal channels (handles, frames)
- Large flat parts prone to warpage
- Structural parts needing high stiffness-to-weight ratio

Typical applications:
- Automotive: Door handles, dashboard frames, steering wheels
- Consumer: Furniture arms, tool handles, appliance frames
- Industrial: Pipe fittings, valve bodies

Advantages over conventional molding:
- Reduces clamp tonnage by 30-50 percent
- Eliminates sink marks without increasing cycle time
- Reduces part weight by 10-30 percent
- Lower residual stress means less warpage

Equipment needed:
- Nitrogen generator or gas cylinders
- Gas injection unit with pressure control
- Modified mold with gas seals and venting
- Special nozzle design or gas pins

Design guidelines:
- Gas channel thickness should be 1.5-3x adjacent wall thickness
- Channel geometry should provide smooth g