The interior of a heating cylinder (2) is divided into a first stage (5) and a second stage (7) due to the shape of a screw (3). A first compression zone in which a resin is compressed is formed in the first stage (5). A starvation zone (7a) in which an inert gas is injected and a second compression zone in which the resin is compressed are formed in the second stage (7). A barrier flight (13) that is obtained by combining a main flight (14) and a sub-flight (15) having a greater lead angle than the main flight is provided to a section of the screw (3), said section corresponding to the first compression zone. A multiple flight is provided to another section of the screw (3), said section corresponding to the second stage (7).

A method of fabricating an injection-molded component is provided. The method includes the step of introducing pellets into an injection barrel of an injection molding machine. The pellets include a first supercritical fluid. The pellets are plasticized in the injection barrel and a second supercritical fluid is injected into the plasticized pellets. The second supercritical fluid and the plasticized pellets are mixed to form a mixed material. The mixed material is injected into a mold.

A method of forming a component of a vehicle heating, ventilation, and air-conditioning system from polymeric material includes providing a molding system including at least one mold cavity defining the component. A base resin is introduced to the mold system via an inlet. A chemical foaming agent is blended with the base resin to form a composition. The composition is then further heated and blended under pressure, wherein the chemical foaming agent decomposes within the composition. The composition is introduced to the mold cavity, wherein a reduced minimized pressure of the mold cavity facilitates initiation of a nucleation of the composition, wherein the composition expands to fill the mold cavity.

A method of fabricating a foamed, injection-molded component is provided. The method includes the step of plasticizing pellets including a first polymeric material and a second polymeric material within an injection barrel to form an injection material. The first polymeric material defines a first phase of the injection material and the second polymeric material defines a second phase of the injection material. The first and second phases of the injection material are immiscible. The injection material is injected into a mold to fabricate the foamed injection-molded component having microscale, microcellular voids. Upon tensile loading, submicron, secondary phase cavities are formed in the injection-molded component, resulting in improved ductility and toughness.

A gas concentration estimation method used in an injection device for foam molding configured to melt and feed a resin by rotating a screw in a heating cylinder, form a non-filled section in which molten resin is depressurized and the heating cylinder becomes a non-filled state, and supply gas to the non-filled section such that the gas dissolves in the molten resin, the method including estimating the gas concentration in the molten resin from following equation (c1) and a passing time T, which represents a time required for the resin to pass through the non-filled section

[00001]$\begin{array}{cc}\frac{\mathrm{dC}}{\mathrm{dt}}=k\left(C^{*}-C\right)& \left(\mathrm{c1}\right)\end{array}$

where dC/dt: CHANGE RATE OF GAS CONCENTRATION IN MOLTEN RESIN [g/(m.sup.3s)] k: CONSTANT [/s] C*: SOLUBILITY OF GAS [g/m.sup.3] C: GAS CONCENTRATION IN MOLTEN RESIN [g/m.sup.3]