Abstract: The diffused feature of gas penetration polymer melt during gas-assisted injection molding is studied. Results show the degree that gas lashed polymer melt is severe, and there are some complex fluid patterns and diffused feature near the point of gas injection. When there is some distance between the point to which the gas bubble penetrated the polymer melt and the point of gas injection, the gas bubble is even. At the tip of the gas bubble, it becomes long and thin for the second penetration. Some useful technology of gas-assisted injection molding development and mould design guildlines are obtained by means of experiment and theoretical analysis.

Key words: Analysis, Efflux diffused feature, Gas-assisted injection moulding, High-pressure gas