A stepped flight is formed on a screw of an injection molding machine. The stepped flight is a flight in which a step-shaped step portion is formed on a top portion thereof. The top portion of the flight includes a large diameter portion on an upstream side and a land portion on a downstream side. When a gap ratio m of a gap H.sub.1 between the land portion and a bore of the heating cylinder to a gap H.sub.2 between the large diameter portion and the bore is defined as H.sub.1/H.sub.2, the gap ratio m is selected to be 2.3≤m≤6.4.

A stepped flight is formed on a screw of an injection molding machine. The stepped flight is a flight in which a step-shaped step portion is formed on a top portion thereof. The top portion of the flight includes a large diameter portion on an upstream side and a land portion on a downstream side. When a gap ratio m of a gap H.sub.1 between the land portion and a bore of the heating cylinder to a gap H.sub.2 between the large diameter portion and the bore is defined as H.sub.1/H.sub.2, the gap ratio m is selected to be 2.3≤m≤6.4.

Provided is an injection molded article containing a copolymer containing tetrafluoroethylene unit and a fluoro(alkyl vinyl ether) unit, wherein the content of the fluoro(alkyl vinyl ether) unit of the copolymer is 3.9 to 4.8% by mass with respect to the whole of the monomer units, the melt flow rate at 372° C. of the copolymer is 11.0 to 19.0 g/10 min, the melting point of the copolymer is 296 to 305° C., and the amount of fluorine ions dissolving out from the injection molded article into water is 7,500 μg/m.sup.2 or lower.

Provided is an injection molded article containing a copolymer containing tetrafluoroethylene unit and a fluoro(alkyl vinyl ether) unit, wherein the content of the fluoro(alkyl vinyl ether) unit of the copolymer is 3.9 to 4.8% by mass with respect to the whole of the monomer units, the melt flow rate at 372° C. of the copolymer is 11.0 to 19.0 g/10 min, the melting point of the copolymer is 296 to 305° C., and the amount of fluorine ions dissolving out from the injection molded article into water is 7,500 μg/m.sup.2 or lower.

A plasticizing device includes a screw that has a grooved face provided with a first groove, a barrel that has an opposed face and a communication hole communicating with the first groove at the opposed face, and a heating section that heats a material supplied to the first groove, wherein the first groove includes a central portion opposed to the communication hole, a material supply portion that is provided at an outer circumference of the grooved face , and a coupling portion that couples the central portion to the material supply portion, a second groove that is coupled to the communication hole is provided and when viewed from the rotational axis direction, an end at the outer circumferential side of the second groove is located inside a track drawn by a boundary line between the material supply portion and the coupling portion when the screw is rotated once.

A plasticizing device includes a screw that has a grooved face provided with a first groove, a barrel that has an opposed face and a communication hole communicating with the first groove at the opposed face, and a heating section that heats a material supplied to the first groove, wherein the first groove includes a central portion opposed to the communication hole, a material supply portion that is provided at an outer circumference of the grooved face , and a coupling portion that couples the central portion to the material supply portion, a second groove that is coupled to the communication hole is provided and when viewed from the rotational axis direction, an end at the outer circumferential side of the second groove is located inside a track drawn by a boundary line between the material supply portion and the coupling portion when the screw is rotated once.

An injection molding apparatus includes an injection-molding mold including a fixed mold and a movable mold, the fixed mold having a gate opening into which a molding material flows, the movable mold having a cavity and being configured to be separated from the fixed mold during mold opening; a hot runner including a nozzle having a channel that guides the molding material to the gate opening, and a heater, the hot runner being disposed in the fixed mold; and a control unit that controls a temperature of the heater to adjust a temperature of the hot runner. The control unit controls the temperature of the heater to a first temperature when the molding material is injected from the hot runner to the cavity, and after the injection of the molding material is completed, controls the temperature of the heater to a second temperature that is higher than the first temperature.

An injection molding apparatus includes an injection-molding mold including a fixed mold and a movable mold, the fixed mold having a gate opening into which a molding material flows, the movable mold having a cavity and being configured to be separated from the fixed mold during mold opening; a hot runner including a nozzle having a channel that guides the molding material to the gate opening, and a heater, the hot runner being disposed in the fixed mold; and a control unit that controls a temperature of the heater to adjust a temperature of the hot runner. The control unit controls the temperature of the heater to a first temperature when the molding material is injected from the hot runner to the cavity, and after the injection of the molding material is completed, controls the temperature of the heater to a second temperature that is higher than the first temperature.

A shaping machine includes a stationary first mold mounting plate, a second mold mounting plate movable with respect to the first mold mounting plate, a tubular snorkel fixedly secured to the second mold mounting plate, and an injection unit for plasticizing and injecting a molding material. An abutment is designed so that, in the opened condition of the closing unit, the injection unit can be braced against the abutment, and so that, in a closed condition of the closing unit, the injection unit is freed from the abutment by the force action of the snorkel on the injection unit.

A shaping machine includes a stationary first mold mounting plate, a second mold mounting plate movable with respect to the first mold mounting plate, a tubular snorkel fixedly secured to the second mold mounting plate, and an injection unit for plasticizing and injecting a molding material. An abutment is designed so that, in the opened condition of the closing unit, the injection unit can be braced against the abutment, and so that, in a closed condition of the closing unit, the injection unit is freed from the abutment by the force action of the snorkel on the injection unit.