fusant injection, the plastic fusant is quantitatively injected into the mold cavity. In this stage, it is very similar with traditional injection molding. We often call a gas-assisted injection as “ underfeeding injection”, because in this stage, the injection volume takes up only 55%–80% of the volume of mold cavity. Whereas the specific injection volume varies with different molding products to ensure that the surface of sufant will not be blown through upon the injection of high-pressure gas and thereby acquiring an ideal aeration volume.