Computer simulation and experimental verification of gas-assisted injection molding

A CAE software has been developed to simulate the gas-assisted injection molding process. The software considers polymer compressibility in both filling and post-filling stages. It includes features such as packing from the polymer entrance, valve gate close/open option, overflow design, and multiple gas pressure or volume controls. Gas penetration is studied in terms of different shot sizes, delay time and gas pressure by numerical simulation. Experimental verification has also been carried out, which shows that the CAE software can simulate the gas penetration pattern quite well. The fingering can also be predicted. A common technique for modeling gas channels is discussed. This paper will show that improper modeling can cause artificial fast cooling in the gas channels, which will hinder the gas penetration in the numerical simulation.