gasassisted

Gas-assisted injection molding, commonly referred to as gas-assisted molding, is a manufacturing process that uses an inert gas, typically nitrogen, injected into the molten polymer within the mold. The gas forms hollow sections and helps push the melt to fill the cavity, producing lightweight parts with improved surface finish and reduced sink marks.

In operation, the mold is filled with conventional plastic melt, after which the gas is introduced through a dedicated valve and nozzle into the molten material. The gas creates a hollow core near the molded surface while the core remains relatively solid, supporting the part as it cools. Once the part is filled and subsides, the gas pressure is maintained to stabilize the shape, and the gas is vented before ejection. The result is a part with a thin external shell and a hollow interior.

Equipment and materials for gas-assisted molding include a standard injection molding machine equipped with a gas supply system, including a gas control valve, manifolds, and appropriate nozzles integrated into the mold. Process parameters such as gas pressure, timing, and amount of gas are closely controlled to achieve the desired wall thickness and dimensional accuracy.

Advantages of gas-assisted molding include reduced part weight, lower material usage, minimized warp and sink marks, and the ability to produce complex geometries with hollow sections. Limitations include higher equipment and mold costs, additional process control requirements, and potential for gas-related defects if venting or timing is not properly managed.

Common applications span automotive components (intricate bezels, handles, and interior trim), appliance housings, consumer electronics enclosures, and other parts that benefit from thin skins and hollow interiors.