Abstract: A gas assisted injection molding system and method in which quantity of an inert gas is applied both internally and externally to a thermoplastic material introduced into an injection mold cavity during formation of an injection molded part. The system includes first and second mold portions defining a mold cavity. An injection means injects a quantity of a thermoplastic material into the mold cavity to form an injection molded part within the cavity. At least one internal gas inlet is provided for introducing a first quantity of gas into a portion the thermoplastic material to form a gas channel therein. The gas within the gas channel presses the thermoplastic material against a mold parting line defined by the intersection of the mold portions and forms a seal between the mold cavity and the mold parting line.

Abstract: An injection mold apparatus has a core and cavity halves. One or more gas poppet valves are affixed in the injection mold either in the movable and/or in the stationary halves of the mold. The poppet valves (or poppets) are located to open into a mold portion formed in the cavity between the movable portion of the injection mold and the fixed mold portion when the mold portions are closed. At least one gas line is connected to the poppets and to a gas pressure source and is adapted to open the poppets to the passage of nitrogen or other gas into the mold following the injection of molten plastic into the closed mold halves. Porous metal covers may be used to cover the opening in the mold either the movable and/or stationary halves of the injection mold in lieu of the gas poppet valves, and the gas pressure through the porous metal cover can be used to carry out the molding operation.

Abstract: A mold apparatus and method is used to form a solid injection molded plastic part having no internal voids, a Class A finish, a sink-free exterior appearance surface, and unevenly distributed structural detail extending from the opposite surface, the detail including free-standing reinforcement ribs, attachment bosses, and the like. A charge of hot melted thermoplastic and pressurized gas are sequentially injected into a mold cavity defining the shape of the desired part, the plastic not filling the cavity and being simultaneously received in shaped recesses and grooves which form the structural detail. The pressurized gas forces the hot plastic from one mold half against the other mold half, and into the recesses and grooves, and is maintained during cooling. A gas seal is formed by the plastic to prevent gas in the mold cavity from reaching the finished exterior surface of the part during shrinkage of the plastic.

Abstract: A mold apparatus and method is used to form a solid injection molded plastic part having no internal voids, a Class A finish, a sink-free exterior appearance surface, and unevenly distributed structural detail extending from the opposite surface, the detail including free-standing reinforcement ribs, attachment bosses, and the like. A charge of hot melted thermoplastic and pressurized gas are sequentially injected into a mold cavity defining the shape of the desired part, the plastic not filling the cavity and being simultaneously received in shaped recesses and grooves which form the structural detail. The pressurized gas forces the hot plastic from one mold half against the other mold half, and into the recesses and grooves, and is maintained during cooling. A gas seal is formed by the plastic to prevent gas in the mold cavity from reaching the finished exterior surface of the part during shrinkage of the plastic.

Abstract: A mold apparatus and method is used to form a solid injection molded plastic part having no internal voids, a Class A finish, a sink-free exterior appearance surface, and unevenly distributed structural detail extending from the opposite surface, the detail including free-standing reinforcement ribs, attachment bosses, and the like. In the method the mold portions of the mold apparatus are closed, charges of molten thermoplastic and pressurized gas are sequentially injected into a mold cavity defining the shape of the desired part, and the mold portions are sequentially separated and closed. The pressurized gas forces the hot plastic away from one mold half and against the other mold half, and separation of the mold portions ensures uniform distribution of the pressurized gas behind the hot plastic, which pressure is maintained during cooling.

Abstract: An injection mold apparatus has a core and cavity halves. One or more gas poppet valves are affixed in the injection mold either in the movable and/or in the stationary halves of the mold. The poppet valves (or poppets) are located to open into a mold portion formed in the cavity between the movable portion of the injection mold and the fixed mold portion when the mold portions are closed. At least one gas line is connected to the poppets and to a gas pressure source and is adapted to open the poppets to the passage of nitrogen or other gas into the mold following the injection of molten plastic into the closed mold halves. Porous metal covers may be used to cover the opening in the mold either the movable and/or stationary halves of the injection mold in lieu of the gas poppet valves, and the gas pressure through the porous metal cover can be used to carry out the molding operation.