Gas-assisted injection molding (GAM or GAIM) is an injection molding technique that injects inert, high-pressure nitrogen gas at the appropriate time when the plastic is filled into the mold cavity. The gas propels the molten plastic to continue filling the cavity, while also using gas-holding pressure instead of traditional plastic-holding pressure.

Here's the Ultimate Guide to Gas-Assisted Injection Molding:
1. Process Principle
Injection Phase: A fixed amount of plasticized plastic is filled into the mold cavity. During the filling phase, it is important to ensure that the gas does not damage the part surface and produces the desired effect.
Filling Phase: At various points during or after the injection phase, gas is injected into the mold cavity. The pressure must be higher than the injection pressure to create a hollow interior.
Gas-Holding Phase: After the interior of the part is filled with gas, the pressure exerted by the gas on the hollow interior is called the holding pressure, which reduces shrinkage and deformation.
Demolding Phase: After the cooling cycle is complete, the gas pressure in the mold drops to atmospheric pressure, and the part is ejected from the mold cavity.
2. Technical Advantages
Reduced Stress and Deformation: Reducing residual stress in the part and preventing deformation. Eliminate Surface Sink Marks: This solves the problem of surface sink marks on products, suitable for products with large thickness variations.
Improve Production Efficiency: This shortens product molding cycles and improves production efficiency.
Save Raw Materials: This maximizes plastic raw material savings, with savings reaching up to 30%.
Reduce Equipment Wear: This reduces the clamping force of the injection molding machine, reducing machine wear and extending machine life. This also reduces pressure within the mold cavity, reducing mold wear and extending mold life.
Simplify Product Design: For certain types of plastic products, this allows the use of lightweight materials such as aluminum alloy in molds, simplifying complex product designs.

3. Common Defects and Solutions
Gas Penetration: This can be addressed by increasing pre-fill, increasing injection speed, or raising melt temperature.
No Cavity or Too Small Cavity: This can be addressed by reducing pre-fill, increasing melt temperature, and increasing gas pressure.
Sink Marks: This can be addressed by reducing pre-fill, increasing melt temperature, and increasing melt holding pressure.
Weight Instability: This can be addressed by reducing injection speed, increasing back pressure, and improving mold venting. Thin air passage walls: Reduce injection speed, barrel temperature, and gas pressure.
Fingering effect: Increase fill depth, reduce injection speed, and barrel temperature.
Gas entering the screw barrel: Increase melt holding pressure and hold time, reduce nozzle temperature and gas pressure.
Explosion after demolding: Reduce gas pressure and extend hold time.